OS 9-48 Fundamentals of Artillery Weapons 1942

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OS 9-48 Fundamentals of Artillery Weapons 1942 Powered By Docstoc
					                                        OS g-48




      Prepared under the direction of
  the Commandant, The Ordnance School

           Reproduction Plant
         The Ordnance School
     Aberdeen Proving Ground, Md.
                                                                                OS 9-48
       No. 9-48       )                                        THE ORDNANCE SCHOOL
                                                    Aberdeen   Proving Ground, June 1942


                         Prepared under the direction of
                    the Commandant, The Ordnance School

CHAPTER 1.  General ----------------------------------                                1-6
CHAPTER 2.  Cannon ----------------------------------                               7-12
CHAPTER 3.  Breech mechanisms
      SectionI. General --------.:----------------------                              13
            II. Types of breech mechanisms                ----~------              14-20
           III. Operating mechanisms            -----------------                  21-23
           IV. Firing mechanisms           --------------------                    24-29
            V. Safety devices -----------.--------------                               30
           VI. Obturator      ----------------------------                         31-32
CHAPTER 4. Carriages
             I. General    ------------------------------                          33-34
            II. Recoil systems ------------------------                            35-38
           III. EquiUbrators --------------------------                            39-43
           IV. Supporting members of the cannon--------                            44-48
            V. Elevating mechanisms             -----------------                  49-51
           VI. Traversing mechanisms               ---------------                 52-55
          VII. Axles --------------------------------                              56-59
         VIII. Bogies -------------------------------                                 60
           IX. Trails, outriggers, and spades -----------                          61-63
            X. Equalizers'      ---------------------------                        64-65
           XI. Firing supports        -----------------------                      66-68
APPENDIX I. Glossary ---------------------------------                             74-77
         II. List of references    ------------------------                           78
INDEX    ------------------------------------------------                          79-82 ~

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                          ORDNANCE SCHOOL

                       LIST OF ILLUSTRATIONS
Figure No.                     Description
                                                                             Page        ~
     1       'I'ypes of cannon -----                                     _
     2       Interior components of a tube                         .:.   _      ~ ~
     3       Built-up cannon -----                             '         _               ij
             Wire-wrapped cannon -
             ~onobloc cannon ---
             Rifling -------
             Interrupted-screw    breechblock (schematic)
     9       Stepped-thread breechblock (schematic)      .:              _     13
    10       Vlelm breechblock                                           _
    11       Eccentric-screw     breechblock                             _     15
    12       Drop-block breechblock                                      _
    13       Horizontal sUdmg-.wedge breechblock                         _     15
    14       Operation of sUdmg-wedge breechblock                        _      16
    15       Operation of semiautomatic breech mechanism           ----- _      17
    16       Extractor    ------
    17       Horizontal-swing breechblock carrier    --,-----------             19
    18       Vertical-swing  breechblock carrier  ---------------               19
    19       Tray-supported   operating mechanism                        _      20
    20       Continuous-pull firing mechanism                            _      22 \
    21       L'lertia firmg mec~anism                                    _
    22       PerCUSSion-hammer firing mechanism          ------------           25
    23       Firing mechanism block                                      _
    24       DeBange obturator                                           _
                                                                                ~~ ~
    25       16" gun on barbette carriage, concrete emplacement-                30~
    26       Gun on disappearing carriage (loading position) -----              30 ~
     27      Disappearing carriage (schematic)                           _
     28                                                                         30 ~
             Traverse methods for railway artillery                      _
     29      Recoil methods for railway artillery                        _
             Towed carriage                                              _      32 •
             Recoil brake ---                                            _      33.
             ThrottUng grooves                                           _      34 '.
     32                                                                         34 .
     33      Throttling grooves - -                                      _
                                                                                35 '1
     34      Throttling bars ---                                         _

             Throttlmg rod ----                                          _      36 ;~
     35                                                                         37,.
     36      Variable recoil - --                                        _
     37      Variable recoil mechanism                                   _      38
     38      Spring counterrecoil mechanism                              _               ,~

             Hydrospring recoil system                                   _      39/
     39                                                                         40 1
     40      Direct-contact   counterrecoil mechanism                     _
     41      Floating-piston   counterrecoil mechanism                    _
                                                                                42 ~
     42      Dash-pot buffer --                                           _
              Internal-rod buffer --                                      _     43q
     43                                                                         434
     44       Respirator (schmdler buffer)                                _

                                                                                             OS 9-48

                            LIST OF ILLUSTRATIONS (CON'T)
Figure No.                               Description                                           Page
   45           Spring equilibrator (puller) ----------------------                               45
   46           Spring equilibrator (pusher) ----------------------                               46
   47           Sleigh -----------------------------------------                                  47
   48           Cradle ------~----------------------------------                                  47
   49           Top carriage     ----------------.:::------------------                           48
   50           Bottom carriage       --------------------------------                            49
   51           Elevating mechanism ----------------------------                                  49
   52           Elements of quadrant elevation -------------------                                50
   53           Dependent line of sighting ------------------------                               51
   54           Independent line of sighting -----------------------                              52
   55           Semi-independent      lin~ of sighting -----------------                          53
   56           Construction of elevating mechanisms                 -------------                55
   57 .         Traversing mechanism ------~--------------------                                  56
   58           Axle traverse (sc'hematic drawing) ----------------                               57
   59           Axle traverse with threaded axle and traversing nut -                             57
   60           Axle traverse with separate traversing screw and
                  nut      ------------------------------------------
   61           Pintle     traverse - (schematic drawing) -------.:.-----                         59
   62           Pintle     traverse - construction              -------------------               60
   63           Base     ring and racer traversing mechanism                      --------        60
   64          Axle -------------------------------------------
   65          Axle for axle traverse         ---------------------------                         62
   66          Axle for pintle traverse          -------------------------                        62
   67          Axle for sprung carriage            ------------------------                      63
   68          Removable bogies (schematic) --------------------                                 64
   69          Split trail --------------------------------------                                65
   70          Simple box trail ---------------------------------                                66
   71          Modified box trail -------------------------------                                 66
   72          Outriggers, railway artillery            ---------------------                     67
   73          Outriggers, antiaircraft artillery             -----------------                  68
   74          Fixed spade ------------------------------------                                  68
   ',5         Detachable spade --------------------------------                                  6~
   76          Hinged spade       ----------------------------------                             69
   '77       ' Types of equalizers        -----------------------------                          71
   78          Firing jack ------------------------------------                                  72
   79          Firing segments --------------------------------                                  73
   80          Rotating cam -----------------------------------                                  75
   81          Projecting cam ---------------------------------                                  75
   82          Subcaliber gun ----------------------------------                                 77
   83          Subcaliber tube ---------------------------------                                 77

                                                                     OS 9-48
               FUNDAMENTALS OF ARTILLERY WEAPONS                       1-4

                                 CHAPTER 1

Purpose -------------------------~----------------------                       1
Scope --------------------------------------------------                       2
References --------------.-------------------------------                      3
Artillery  -------------------------------~!:---------------
Types of cannon -----------------------------------------
Components of an artillerj weapon ------------------------                     6

        1. PURPOSE. - This text is published for the information and
guidance of all concerned with artillery weapons. It will be especially
valuable in the basic training of ordnance personnel and may also be used
as a reference book for the using-arms and services.

        2. SCOPE. - This text deals with the fundamentals of artillery
weapons without regard to any particular weapon. The basic construction
and operation of the various components of artillery weapons are discussed,
but mechanical details are not described except when necessary to illus-
trate principles. Automatic weapons are not covered in this text.
        3. REFERENCES. - A list of references will be found in appendix II.

         4. ARTILLERY. - a. Definition. - Artillery is a general term
referring to three main types of cannon, namely: guns, howitzers, and
mortars.    The term denotes weapons which are mounted upon fixed or
mobile mounts, and which have calibers (see app. I) equal to or greater
than 0.60 inch. All other weapons, with calibers less than 0.60, are
classified as small arms, and include machine guns, guns fired from the
shoulder, pistols, and revolvers.

       b. Classiflcation. - Artillery may be classified under such broad
headings as field artillery, seacoast artillery, antiaircraft artillery, etc.
It may be further classified as fixed artillery or mob~le artillery.
        (1) Fixed artillery. - This type is permanently installed on land
and sea frontiers for the protection of important areas ...
        (2) Moblle artlliery. - This type is designed for movement from
place to place. It ma~' be divided into three main categories as follows:

        (,!) Railway artillery. -This is designed to be transported on, and
flred from, railway cars. Some types of railway artillery may be trans-
ported on railway cars and fired from prepared ground positions.

       (~) Self-propelled artillery.     - This combines     the weapon and
motive power into a single vehicle.

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  4-6                      ORDNANCESCHOOL

       (.£) Towed artillery. - This depends upon outside motive power
(prime mover) such as a truck or tractor.

       5. TYPES OF CANNON. (Fig. 1.) - a. Mortar. _ A mortar is a
comparatively short, stubby weapon which operates between elevations of
approximately 45° and 85° and has a low muzzle velocity.

        b. Howitzer. - A howitzer is a medium-length cannon which oper-
ates at elevations of 0° to approximately 65° and has a medium muzzle

  81 ~M   ~ORTAR     75   MM   HOWITZER            75   MM   GUN

                   FIGURE 1.- TYPES OF CANNON.

        .£. ~.    - (I) General. - A gun (sometimes referre.? to a~ a rifle)
Is a long-barreled cannon, which operates at elevations of 0 to 65 and has.
a high muzzle velocity. The gun of today possesses practically all of the.         •
characteristics    of the howitzer and might be called a long-'!Jarreled

        (2) Subcallber guns and tubes. - In many instances of practice
firing of cannon, guns of smaller callber are employed to reduce the
expense of ammunition. These auxiliary guns are called subcallber can-
non (see app. I), of which there are two types:

        (~ SubcaUber guns. - A subcaliber gun is a gun which ismounted
on the outside of, and above, the parent cannon.

       (b) Subcaliber tubes. - A subcaliber tube is a tube (see par. 7)
whi:h 1s-mounted In the bore of the cannon with which it 1s used.

         6. COMPONENTS OF AN ARTILLERY WEAPON. _ Essentially,
an artillery weapon consists of a cannon, a breech mechan1sm, and a
carriage. These components are described in the succeeding chapters of         I

th1s text.

                                                                                              OS 9-48
                       FUNDAMENTAIB OF ARTILLERY WEAPONS                                        7-8
                                         CHAPTER 2

   Tube ---------------------------------------------------                                            7
   Interior components of a tube -----------------------------                                         8
   Cannon construction ------~------------------------------                                           9
   Breech ring -----------------------------~--------------                                           10
   RUling -------------------------------------------------                                           11
   Removable liner ----------------------------------------                                           12

           7. TUBE. - The tube, or barrel, of a cannon generally refers to
   the enUre cannon assembly less the breech mechanism.        The term tube
   may also I be used to denote the inner cylinder of a cannon, around which
   strengthening hoops may be shrunk or reinforcing wire may be wound.
   (See figs. 3 and 4.)
           8. INTERIOR COMPONENTS OF A TUBE. (Fig. 2.) - The inte-
   rior of a tube is subdivided into six parts as follows:

           a. Breech recess. - This is the space at the rear                             of the tube
   which is prepared to receive the breechblock.
            b. Gas check seat. - This is a seat against which the obturator
~ -fits to form a gas tight seal.

    BREECH   RECESS                               MAIN BOR£

                      POWDER   CHAMBER

                                                              ///////   /"/.   /.   /'    '


          ~: Powder chamber. - The powder chamber is that portion of a
   tube which receives the powder charge or, in the case of fixed ammunition
   (see app. I), holds the cartridge case.

             d. Centering slope. - Thp. centering      slope is the portion of the

OS 9-48
  8-9                     ORDNANCE SCHOOL

bore just forward of the powder chamber.    It slopes forward to Uft the
projectile from the powder chamber floor and centers it on the main bore.

        e. Forctng cone. - The forcing cone, which is made by cutting away
the rinGig at the rear of the main bore, assists in centering the projectile
and stops its forward motion when it is rammed.

        !.. Main bore. - This is the forward part of the tube, containing
the rlned portion of the bore.

       9. CANNON CONSTRUCTION. - There are three main types of
cannon construction: namely, built-up, wire-wrapped, and monobloc.

        a. Built-up cannon. (Fig. 3.) - A built-up cannon is one in which
the tube-is reinforced by means of hoops shrunk around it. The number

and arrangement of these hoops vary with different types and calibers of
cannon. Hoops are named according to their position on the tube, e.g.,
~~~~~~ hoop, muzzle hoop, etc. Locklng hoops are used to joIn adjacent

                                                            .....zzu;   HOOP   !
                                     .JACUT   _

                    FIGURE 3. - BUILT-UP          CANNON.                      J

         !C. Wlre-wraPEed cannon. (FIg. 4.) - A wire-wrapped cannon Is one
 in which the tube Is reinforced by Winding wire of hIgh tenslle strength      I
                            WIN:                                               I

                  FIGURE 4. - WIRE-WRAPPED

                                                     CANNON.                   I

                                                                      OS 9-48
                FUNDAMENTALS' OF ARTILLERY WEAPONS                     9-11

  around it. The number oflayers of wire will vary accordingto the strength
  requirements of different cannon. Depending upon the design of the can-
  non, the wire is inclosed in either of the two following ways:

          (1) By placing a jacket over the wire wrapping.

          (2) By shrinking on hoops as in the built-up cannon.

          c. Monobloc cannon. (Fig. 5.) - A monobloc cannon is one which
  is formed in one piece from a forging or casting. The casting may be
  either a simple casting or a centrifugal casting (made by pouring molten.
  steel into a horizontal cylindrical mold which is rotating at high speed).
  The forging or casting is subjected to either or both. of the following pro-

          (1) Heat treatment.

          (2) Cold-working or autofrettage.   In this process, the forging
  or casting is initially stressed by applying hydraulic pressure to the
  inside of the bore.

                     FIGURE 5. - MONOBLOC C:u~ON.

          10. BREECH RING. (See fig. 5.) - A breech ring is a ring, or
 bus:.~ng, which is screwed or shrunk onto the rear end of a cannon. ~
 provides a seat for the breechblock. This seat is of greater diameter than
 that of the tube and hence provides a greater screw-thread    bearing area
 than the tube could provide. The increase in thread area allows the length
 of the block to be reduced.

          11. RIFLING. (Fig. 6.) - Rifling consists of a number of spiral
 grooves in the surface of the main bore. Its purpose is to impart rotation
 to a projectile, thereby stabilizing it in flIght. The terms pertaIning to
 rifling are as follows:

           ~. Grooves. - The grooves are the depressed portions of the
, rifling. The number and depth of grooves vary with different cannon. The

                                           ORDNANCE SCHOOL

                                  ro JVes is from six to nine times the caliber      (in inches).

            t. Twi",t. - Rfling twist is defined as the inclination of the spiral
"r .Nf':'- w;tr re
   J                       t to the axis of the bore.  Twist may be uniform or
 nrrf ~':,ir. 11.    't is us ally expressed   as one turn in a length of so many
(Hi!'  PI".     FrJr pxa pIe, a l2-inch     gun having a twist of one turn in 25
(HiJit        i ii atps a twist of one turn in every 25 feet of gun length.
             (>   :;

                   ('. Land . - The        surfaces   of the bore   between    the grooves     are
 ~J.l   f'        lind-s-.--

                                           FIGURE 6. - RIFLING.

                       12. RE       OVABLE LINER. -A removable         liner is a cylinder, con~
                                 letp rifled bore, which is inserted into and locked on the
                                   e proper.     In cannon of high muzzle velocity,    the rifl ing
                                lyerode      (see app. I). The purpose of the removable      lIner
                                 ick reconditioning     of cannon by eplacing worn liners with

                                                                                 OS 9-48
                   FUNDAMENTALS' OF ARTILLERY WEAPONS                             13-14

                                          CHAPTER 3

                                  BREECH MECHANISMS
SECTION I. General -----------------------------------                             . 13
        II. Types of breech mechanisms             ----------------                14-20
       III. Operatlng mechanisms ----------------                   ------         21-23
       IV. Firing mechanisms -----------~-------------                             24-29
        V. Safety devices ------------------------------                               30
       VI. Obturator    ---------------------------------                          31-32

                                           SECTION I

General     --------------------------------------~---------                          13
        13. GENERAL. - A breech mechanism is a mechanical device for
opening and closing the breech, or rear end~ of a cannon before and after
loading and for firing the round of ammunition which has been inserted.
The components are:

          a. Breechblock.
          b. Operating mechanism.
          c. Firing mechanism.
          d. Safety devices.
        e. Obturator included only in the breech mechanisms                    of cannon
firing separate-loading ammunition (see section VI).

                                          SECTION II

                          TYPES OF BREECH MECHANISMS
General ------------------------------------------------                              14
Inteirupted-screw        breechblock         ---------------------------              15
WeUn breechblock           --------------------------------------                     16'--
Eccentric-screw        breechblock -----------------------------                      17
Sliding-wedge breechblock             -------------------------------                 18
Semiautomatic breech mechanism -------------------------                              19
Extractor     ----------------------------------------------                          20
          14. GENERAL. - There are three general types of breech                  mech-
anisms,    classifled according to their breechblocks as follows:

          a. Interrupted-screw           type.
          b. Eccentric-screw           (Nordenfeld) type.
          c. Sliding-wedge         type.

  J   ,   -'       j

                                                ORDNANCE     SCHOOL

                        .1     ERRTJP'IED-,5CREW       BREECHBLOCK.           _ a. Schematic      il-
          3.;        (1' .7.) - To illustrate
                                  0                  the basic operation       oran interrupted-
                  'p    U h k, onsider         a threaded     bolt engaged       in a nut.    If the
        'i           t.!          :UP rut aw yon one-half       of the circumference,       and th
tI      'if ,'of      rlf   n t 'ire cut away on the opposite half, then the bolt can b'
    l'r    ~.3!";       7f,t through the nut. If the screw is given half a turn, the re-
IT '~rl          U",rf'" 1s of hp bolt will engage
               I r                                        the remaining       threads   of the nuL,
  ~I    (~yr ) ......, -; hp lalt on place. The convenient            feature of this arrang0-
    . r.'          at;t      '1 b s th    bolt to slide all the way into the nut and then
              s ) .. y a flali-t, rn to lock the bolt in place.             If the threads     wer
              '1 ray             tl"ned above, several
                                'j,   (                    t11rns of the boll would be neces-
... y          '1 h;r
               f            1--,  amp result.

          r; •         I    7

                                          F RRTJPTED-0CREW     BREECHBLOCK     (SCHEMATIC).

                                                                                  O. 9-48
               FUNDAMENTAL'          OF ARTILLERY                WEAPO     S       15-16

and block are fully engaged,      and the block         '5   10 k d.

             I G. WELIN I RI<,ECI
bre( chblock i:3 a rnodifc, tic>         r
:;c ri bpd in paraGraph 1~). COIl"    • r
D). LPl thv lhn ads of th l ult l    i   '   •   'J,'

l)w     ci rcumf   rcnc  for onE -th' ~ C.       t.t

   FIGURE    9. - STl',PPED-THR          AD E REECH            L )CK (('('HE   ATIC).
j'      . -   ~

      ,'-     7
                                              ORDNANCE       SCHOOL

1.1' J' ;n~'" ~12.rt              for two-thirds     of the height; on the next quarter          of Lhe
('          'lr',fer n p for the full height (threads               completely    cut away).      This
l(.':iV~'. he rpmaining                 uarter of the circumference       with a full thread.      The
                  i co a te p d thread covering three-quarters              of the circumference
                     )1t. Lpt the nut be cut away correspondingly,             so that the bolt can
                    frpply 'nto it. In order to engage the stepped threads of the bolt
fully '.vi h tho e of th nut, it now requires                    only a quarter turn of the bolt,
Wf.f          1"1      i rf luire      one-half of a turn in the interrupted        screw shown in
f' 1 I 7. !if> CP, it is seen that by stepping a thread,                       the rotation neces-
. 1.ry tr) 1) Y. t e 'olt, or breechblock,                 is decreased.     By this means, also,
  tll hreajp               ;lrpa may cover a larger          portion of the block surface,        e.r~.,
    Jr)-t        . r L, t f( p-fo       ths, or even more. In the interrupted-screw           breech-
t 1v'y., J[,ly (Jne-half the block area is threaded.                      This larce increas          in
  Lrr.8, (j arp3, l.ttai p by the Welin type permits                        the use of a smaller
   l(jroy'.          II ad al       I' ctice,  the W lin block has several           stepped-thread
~)l (' 01'          • a1 (~ [,atprj w'th plain sectors,      as shown In figure 10.

                                  T   JTJHF   10. - WELIN    BREECIIBLOCK      .

                  . 7.        RII'-.j('REW
                         J'("".                    BREECHBLOCK.         (Fig.  11.) - The
     • 'I'
                                  )1' if' ipl  ,typP of bre chblock is ylindrical    and is
                       z f "'[')1' s rhcp La screw into Lhe breech recess,           which
               r, L• .,.'../ t: rl"1'1F"!.    The breechblock      is much larger than he
             r, . x;."; 'L) t which il rotates              oes noL coincid. with axi:; of
                r 'n '...; J -...:ihapE' off-center        opening in th block called I he
                      Nt. ('h coincides           with th bar      when the block is in i Ls
                     t f arr munition is inserted          into Lhe bore through the load-
                        ammunition inserted as far as it will go, the breechbIocl<
Is rr)ta (~1 'it rJ     i.) axis approximately            a half-I' volution to its clo:; 'd
  jsitlrJ . 1 L ff) a ;on locatf's the loading recess away from the bore and

                                                                                                               00 . -48
                   FUNDAMENTALSO                         ARTILLERY             WEAPO            ;'              17-18

causes th so lid wall of the lock to s 'al t E bn t.: h. To c)p n th br           eh,
the block is mer ly rotat d in thE         0 'tt.:   ir~ Cti0fl    r til thE loading
recess again corn s into aligr ill nt with tIW t ,)ff'.   T~ (> t lock remains     in
Uw brc       eh during       the op ration          of Opt n'n~ or          10 'n€, t p hI'          E   eh.


                   r   r1RING PIN

                           RRf fC ~ Of

              FIGURE]         1. - ECCE             TRIC -~)CREW            REECIiP       LOCK.

             18. ;;LIDING-WEDGE                REEC'HE L
wE'cl[~eIn'('f'chblock      is f(,(.talfular'n             l'

p:lI[<lr r('c('~~:), und(>r the act io            of'
c[o:.;(':; thE>])1'1' ch. ThE bloc\.; P'              ~'li i
cl('!H'ndinp,- upon the particular               \.: ~i Tr. i tLt l f( f C). I,' C' ani:;n.
                                                   .                                            Whf'fC
I!lf' tllolion of UlI' bl'l,pchbloc'         is Vt rtic"1.., tLI IT.! d c.1I,:,'!l i, c]: :~'ifit d a,'
UH' drop-IJ10ck        tyP(' (fip;. 1?).        Iht f( tl.l n i ", i.~ L Jri",l I.l' 1, thl block
i~j callpd    a horizontal          slidir   f-Wt    1";1 trl   I   C[I 1   l< ('   •   1:').

FIGUH.E 12. - DHOP-I LOCK                                       IGU E :•. - HORIZO TAL
       liH.I'~b~CIIB LOl'K.                            SLID       G-Wf>D E REE HBLOCK.

                                                       -1 f -
OS 9-48
                          ORDNANCE SCHOOL

         b. Operatlon. - Figure 14 illustrates  the general operation of a
sliding-wedge breechblock. In A, the breechblock is open, ready to receive
the, ammunitlon.    The cartridge is shoved into the breech almost to a
seated positlon, as shown in B. In C, under the action of the operating
mechanism, the breechblock Siides over the breech face. The breech-
block is beveled on its forward face. This bevel forces the cartridge to a
seated position, and the breechblock seals the cannon, which is then ready
for firing.




          19. SEMIAUTOMATIC BREECH MECHANISM. _ a. General. _
A semiautomatic breech mechanism is one in which some ofthe operations.
of opening and closing the breech, and of loading or extracting th~ car-
tridge, are performed manually, and others are performed automatically
by utilizingthe energy of recoil or the pressure of th.e powder gases. The
sliding-wedge system is partiCUlarly adaptabl.e to semiautomatic operation.

         b. Operation. - The .operation of a semiautomatic    breech mecha-
nism is lllustrated schematically in figure 15. A shows the system at rest,
with the operating crank (connected to the breechblock) on the cannon, and
the operatingcam     (see app. I) mounted on a frame which is part of the
carriage. As the cannon recoils (B), the crank slides under the cam. The
cam then automatically returns totts original position.     During counter-
recoll (C), the crank, which is free to rotate, strikes the fixed cam. This
causes the crank to rotate, thereby opening the breechblock downward
where it is locked open. As the crank rotates, it also stores up energy in
a coll spring. Insertion of a round of ammunition releases the breech-
block and causes the block to close under the action of the coil spring.

                                                OS 9":48


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OS 9-48
                             ORDNANCE SCHOOL

        20. EXTRACTOR. - An extractor is a mechanical          device for with-
drawing a cartridge case from the chamber of a cannon.        The operation of.
one type of extractor is illustrated in figure 16. Opening     the breechblock
causes the extractor to move against the flange on the        base of the car-
tridge case, thereby forcing the case out of the cartridge      chamber.


                        FIGURE ~6. - EXTRACTOR.

                                  SECTION III

                         OPERATING MECHANISMS
General --------------------____________________________              Paragraph21
Carrier-supported      operating mechanism -                 ~-----            22
Tray-supported    operating mechanism       -____________________              23

        21. GENERAL. - A breechblock operating mechanism is a device
which unlocks and Withdraws the breechblock from the breech, swings the
block clear of the breech recess, and then returns tt to the flring, or
closed, position after loading. There are two types of operating mecha-
nisms: namely, carrier-supported    and tray-supported.

eration. - This type of .mechanism performs two cycles in opening or
closing the breechblock, as follows:

        (1) It rotates the block until the threads    on the block are disen-
gaged from the threads of the breech.

         (2) It then withdraws   the block from the breech recess     and swings
it clear of the breech.

                                                                        o      9-48
                 FUNDAMENTALS        OF ARTILLERY   NEAPO     ,               22

                                                                     re chblock
                                                                    Th carrier
                                                                   ing the block

                                                             .('h l n 10 k' an
        c.    OperaUn~ lever.     - Thi .
withdraws      Uw br(' chblock   fro   th                    it to thl firing
p00iUon.     (SC'C' fi~. 17.)

                                                      , (r        'AT   IE.

      I'ICUIU,    1 L - VEl TICA            LEECH   LUCK CARhIER.
1).3       -43
                                           ORDNANCE          SCHOOL

            'J? TRAY - UPPORTED        OPERATING    MECHANISM.     (See fig. 19.)
1.   0 r>ration. - This type of operating      mechanism  is used on the older
far-"I'-r-al'   r>r cannon. It accomplishes  three cycles of motion in opening
r)r c10si        hf> reech:

                  (l)     I rotates the block until its threaded         sectors     are   disengaged
.r   J'[     U,.        hr 'a ed sectors  of the breech.

                  (I)    It tranvlates     the breechblock     to the rear,    pulling     it out of the
r rl   J

           'rh    rprp        ') to a tray.

                (~~) then SWings the block and the tray,                as a unit,    away from      lhe
     I     >rr. lpavir g thE? annan free for loading.

           !:.. Bn>echblo k tray. - The breechblock tray is a wide tray, hinr; d
  ) Lf>t rE'l h ()f a cannon, which supports     the breechblock when it is wi lh-
j ~'lWr. '3.f    r PI. i is swung clear of the breech.



                 F IGURF     1 . - TRAY - 'UPPORTED            OPERATING           MECHANISM.

                                                                         OS 9-48
                FUNDAMENTALS' OF ARTILLERY WEAPONS                        24-25

                                    SECTION IV

                             Fm.mG MECHANISMS
General                                                                Paragraph

Continuous-pull firing mechanism -------------------------                    25
Inertta ftrtng mechanism ---------------------------------                    26
Percussion-hammer     firing mechanism ----- ...      --------------          27
Firing mechanism block ---------------------------------                      28
Electric firing mechanism -------------------------------                     29

        24. GENERAL. - A firing mechanism is a device which causes the
ignitton of the primer (see app. I) which, in turn, ignites the propelUng
charge of a round of ammunition. There are four principal types of firing
mechanisms, namely: conttnuous;pull, inertia, percussion-hammer,       and
        25. CONTllWOUS-PULL Fm.ma MECHANISM. - a. General.-
This type of firing mechanism 1s used on cannon firing fixed ammunition
(see app. I). The complete operation of a continuous-pull firing mecha-
nism is effected by one continuous pull of the lanyard. Actually, there are
three phases in the firing cycle:              .

        (1) Cocking phase. (Fig. 20, !!.) - In this phase, the first part of
a pull on the lanyard compresses the firing pin spring.

         (2) Firing phase. (Fig. 20, £.) - In this phase, the remaining part
of the la."1yard's movement disengages the sear, thus allowing the spring
to expand and force the firing pin against the primer, firing it.        .

         (3) Retracting phase. - In this phase the lanyard slacks, and the
 firing mechanism parts return to their posiUo:l at rest (fig. 20, ~).

          b. Firing lock. (Fig. 20.) - The firing lock is a modern continuous-
 pun ftrii1g mechanism which is in general use in our service.        The com- .
 plete assembly is installed in a recess provided In the breechblock. 'A-
 pull on the lanyard rotates the trigger fork clockwise, which forces the
 firing-pin holder sleeve forward, thus compressing the firing-pin spring
 (flg. 20, B); A further pull on the lanyard causes the sleeve to continue
 fcrward and to earn down the sear, dIsengaging the sear from the firing-
 pin holder. The firing-pin holder then flies forward under pressure of the
 firing spring, and the firing pin strikes the primer, setting itoff (fig. 20, C).
 Upon release of the lanyard, the firing-lock parts return to their positions
 at rest (fig .. 20,~) in the following manner: The firing spring presses for-
 ward on the firing-pin holder and rearward on the sleeve. When the spring
 expands (fig. 20, £). it forces the sleeve rearward against the trigger fork
  at point "X". The trigger fork, lr. turn, presses against lugs on the firing-

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                       ORDNANCE SCHOOL

                             FIRING PIN SPRING

                                                 FIRING PIN




                                                                             OS 9-48
                   FUNDAMENTALS OF ARTILLERY WEAPONS                          25-26

    pin holder at point 'ty". Due to a longer lever arm, the action ofthe sleeve
    on the trigger fork overcomes the reverse pull of the firing-pin holder on
    the fork. Therefore, the trigger fork rotates rearward, drawing the firing-
    pin holder back until it is engaged again with the sear at point "z" (fig. 20, ~).

             26. INERTIA FIRING MECHANISM. (Fig. 21.) - a. Description. -
    The essential parts of an inertia firing mechanism are as follows: guide,
    fi'ring pin, firing spring, cocking lever, sear, stop, retracting spring,' and
    retainer. The complete assembly is installed in a recess provided in the
I   breechblock and is held in place by the retainer.     The guide has two lugs
    on its outside ci~cumference,. namely: lug "A" and lug ''B". The firing
    pin is screwed to the guide and for all practical purposes is integral with
    it. The moving parts are the guide (with firing pin attached) and the stop.
    The guide slides against the breechblock walls. The stop and the retract-
    spring both slide inside the guide on the firing pin. The forward end of the
    retracting spring bears against the stop, and the other end bears against a
    shoulder on the rear end of the firing pin. Figure 21, A shows the system
    at rest.                                                  -

            b. Operation.    - There are three phases in the operation of this
    firing mechanism.
             (1) Cocking phase. (Fig. 21, B.) - In this phase, the cocking lever
    is rotated clockwise. The lower endof the lever bears against lug "A",
    moving the guide rearward and compressing the firing spring until lug
    ''B" passes the sear. Under the action of the sear spring, the sear then
    jumps across the guide in front of lug ''B". The firing spring is now fully
    compressed and tends to shoot the guide and firing pin forward. However,
    lug ''B" bears against the sear, which prevents the guide from flying for-
    ward. The system is now cocked, ready for firing.

            (2) Firing phase. (Fig. 21, C.) - In L~e firing phase, the sear is
    pushed down across the guide and is disengaged from lug ''B". This re-
    leases the guide, which flies forward under the pressure of the firing
    spring. The stop strikes the forward end of the breechblock; the guide
    continues forward until it, too, strikes the breechblock; and the firing pth---
    hits the primer, firing it. The retracting spring is compressed between
    the stop and the shoulder on the firing pin.
              (3) Retracting phase. - In order that the firing pin may not be
     sheared off as the breechblock is opened, it must be retracted, or. pulled
     back, into the breechblock. This is accomplished under the action of the
     retracting spring, as follows: The' compressed retracting spring pushes
     rearward 011 the firing pin and is restrained only at its forward end by
     the stop and breechblock.    The guide (with firing pin attached) is free to
     move to the rear. Thus, the compressed retracting spring expands, pulling
     the firing pin back into the breechblock. The system is then at rest (fig.
     21, ~) ready for subsequent cocking and firing.

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                                    OS 9-48



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                               ORDNANCE SCHOOL

         27. PERCUSSION        -HAMMER       FIRING      ME CHANISM.        _
A percussion-hammer type of firing mechanism is one in which a hammer,
actuated by the pull of a lanyard, strikes the firing pin and fires the can-,
non. Figure 22 schematically shows the operation of one type of percuss ion-
hammer firing mechanism. In figure 22, A the system is shown at rest.
Teeth on the firing hammer arm engage teeth on the rack, and the firipg-
rack spring holds the system in position. !n figure 22, B, the firing ham-
mer is pulled to the rear by the lanyard. This pulls the rack upward,
thereby compressing the firing-rack spring. In figure 22, Q, the lanyard
Is released; the rack Is pulled down by the compressed spring; and the
hammer flies upward striking the firing pin which fires the primer. .
        28. FIRlliG MECHANISM BLOCK. _ A firing mechanism block
(fig. 23) is a detachable part of a percussion-hammer  type of firing mech-
anism. It contains a firing pin and a seat into which a primer is inserted.
With a primer inserted in the block, the entire firing mechanism block is
then screwed into a recess provided in the breechblock. After firing, the
firing mechanism block is unscrewed from the breechblock, the old primer
case is removed, and a new primer is placed in the firing mechanism
block ready for firing the next round. A firing hammer ~trikes the firing
pin, which in turn strikes the primer.

                                                  \     .... :1,","
                                                                      ..". ;,:"M
                                                                            "      I,

               BLOCK   RtMOVED
                                                                 BLOCK INSERTED
             SYSTnt   AT   Rf:ST
                                                                      SYSTEM            r'RED

         29. ELECTRIC FIRlliG MECHANISM. _ An electric firing mecha-
nism uses a firing magneto in circuit with an electric primer.    One side
of the line is connected by an insulated wire to the primer, and the other _
side is grounded to the frame of the cannon. Electric current flowing
from the magneto sets off the primer.

                                                                               OS 9-48
                 FUNDAMENTALS OF ARTILLERY WEAPONS                              30-32

                                     SECTION V

                              . SAFETY DEVICES
General                                                                      Paragraph30

        30. GENERAL. - There are various forms of safety dev~ces de-
signed to prevent accidents. These devices inalude:

        a. Those which prevent operation               of the firing   mechanism   when
the breechblock is not fully closed.

          £.   Those which prevent firing when the cannon is not in battery.

       c. Those which prevent            firing when the cannon 1s disconnected
from the recoll system.
                                     SECTION VI

Obturation                                                                   Paragraph31

The DeBange obturator        ----------------------------------                      32

        31. OBTURATION. - a. Definition. - Obturation is the prevention
of the rearward passage of powder gases into the threads and other parts
of the breech mechanism.    These gases, which have great velocities and
high temperatures,   would soon erode and ruin the breech mechanism and
would materially affect the ballistics of the cannon if a means of obtura-
tion were not introduced.

         b. How effected. - (1) In cannon using fixed or semiflxed ammu-
nitlon.(See app. I), obturation is performed by the cartridge case, which
expa.nds, under pressure in the bore, to a tight seal against the walls of
the powder chamber.
         (2) In cannon using separate-loading ammunition (see app. I), an
obturating device must be included in the breech mechanism to prevent
the rearward escape of powder gases. The DeBange obturator is used
exclusively in our service.

          32. THE DeBANGE OBTURATOR. - The DeBange obturator is
illustrated diagrammatically    in figure 24. A mushroom head is mounted
on a spindle which is attached to the breechblock.  Between the mushroom
head and the breechblock is a plasUc pad made of asbestos, tallow, and
paraffin.    This pad is called the gas check pad. Two steel split rings,
which are ground to seat accurately in the breech recess, encircle the


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                               ORDNANCE SCHOOL

gas check pad, as shown. When the cannon is fired, the gas pressure acts
against the mushroom head, which compresses the plastic pad, as shown
in figure 24, B. This causes the pad to expand radially against the split
rings, whlch 1n turn expand to make a gastight seal against the breech
recess wall. After firing, the gas pressure is dissipated; the plastic pad
returns to its normal shape; th~ split rings contract to their original size;
and the breechblock is then free to open.

                               MUSHROOM                          -POWDER
                         ---     HEAD                            ::PRESSURE

                                             <UNDER *OWDER PRESSURE)

                  FIGURE 24. - DeBANGE OBTURATOR.

                                                                             OS 9-48
               FUNDAMENT ALS OF ARTILLERY WEAPONS                             33-34

                                  CHAPTER 4
SECTION I. General -----------------------------------                         33-~4
        II. Recoil systems -----------------------------                       35-38
       III. Equilibrators ---.----------------------------                     39-43
       IV. Supporting members of the cannon,!:------------                     44-48
        V. Elevating mechanisms ----------------------                         49-51
       VI. Traversing mechanisms
            Axles                           --------------------               52-55
      VII. Bogies                                                                  60
       IX. Trails, outriggers, and spades ---------------
            Equalizers                                              .:.'        61-63
         XI. Firing supports      ----------------------------..;               66-68
                                   SECTION I

General -----------------------------------------------                             34
Types of carriages (or mounts) --------------------------

         33. GENERAL. - A carriage is an assembly which furnishes a
support for a cannon in firing and, in the case of mobile artillery, enables
the weapon to be moved readily from one position to another. A carriage
may consist of a combination of several or all of the following major
Components:     recoil system, equilibrator,   sleigh, cradle, top carriage,
bottom carriage, elevating mechanism, traversing mechanism, axle, trail,
equalizer, firing supports.

           34.' TYPES OF CARRIAGES (OR MOUNTS). -There are two main'
 classifications   of carriages,     namely: fixed carriages  and mobile car-
 riages.     Fixed carriages     include the barbette and disappearing   types.
 Mobil$! carriages    are classified as railway, self-propelled,     and towed

         a. Barbette carriages.   - According to a strict definition, a bar-
bette carriage is a stationary carriage on which a cannon is mounted to
flre over a parapet. Today, however, the term barbette carriage is used
in a broader sense to refer to a stationary carriage, regardless of whether
it fires over a parapet, which is capable of traversing        through large
angles except as limited by a protectlng turret or casemate (see fig. 25).

        b. Disappearing carriages. - A disappearing carriage is one which
holds the cannon behind a parapet during loading (fig. 26) and raises the
cannOn above the parapet for firing. This type of carriage is represented
schematically  in flgure 27. When fired, the cannon recoils to the rear

                                                      ORDNANCE               SCHOOL



                                                                Sleel' and
                                                                Coner ele

   16"     Qun     on

   Borbe     lIe        CO,roo    e

   FIGURE                        5. -       S" GUN ON BARBETTE                        CARRIAGE,       CONCRETE

FIGURE             2 . - GU               0    DISAPPEARlNG                  CARRIAGE        (LOADING            POSITION).

                                 LEVER AXLE      /'              -;
                        '.,I~TER-                     PARAPET
                                                                                                           ,.'   ,',')

                                                                                          LOADING PO::>1TI0N

                 FIGURE               ::1     - DISAPPEARlNG                  CARRIAGE        (SCHEMATIC).

                                                                              OS 9-48
                  FUNDAMENTALS 'OF ARTILLERY WEAPONS                            34

 and downward, pivoting about a lever axle. When fully recolled (flg. 27,
 ~), the cannon is approximately horizontal, and the counterweight is raised.
 The cannon is returned to its in-battery position (see app. I) by the coun-
 terweight, as described in paragraph 38.

           £.. RaHway mounts. - Rallway mounts are c1assifled generally
 accordingto     the methods by which traverse     is obtained and recollis     taken
 up.   .                                              '!:

          (1) Traverse     is accompllshed      by one of the followlng methods,
 (see flg. 28).                                                         .
           (a) By moving the mount along a curved track         or epi (track tra-
 verse).    -

           (~   By rotating the entire car (car traverse).

          (£.) By rotating a top carriage       (se~ par. 51) with respect      to the
 ,car (top carriage traverse).

            (2) Recoll is taken up by allowlngthe mount, or some part thereof,
  to be displaced to the rear. There are four systems of recoll, namely:
, cradle recoll, top carriage recoll, sllding recoll, and rolling recoll. (See
  flg. 29.)

         ~. Self-propelled mounts. - A self-propelled mount is one which
  serves as a carriage for a cannon and has its own engine for providing
  moUve power.                        .

         e. Towed carriages.    - A towed carriage is one which is mounted
 on wheels and is towed by some outside source of power (prime mover).
 This type of carriage is usually connected to its prime mover through a
 trall and lunette. (See fig. 30.)

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                 ORDNANCE            SCHOOL

                                       I !

                                              ~      ::q'
          tz.l                                ~      E-i~
          ~                   tz.l            g:     ~~
          ::-                 ~
                              ~               ~      ~~
                              ::-             F.-t
          ~           I                       ~      ~~
                              ~               ()
                              E-<             ;5
                      I                              :>~
                      I       ~               ~      ~<
          ~           I
                                              tJ     E-i~
                      I                       P..     li-=l
                      I                       0


                                                                                                               OS 9-18
                   FUNDAMENTALS                     OF ARTILLERY                   WEAPONS                      .1-.

                            FIGURE           30. - TOWED                CARRIAGE.

                                                  SECTION          II

                                           RECOIL          SYSTEMS
                                                                                                            P ragraph
Gen ral                                                                                                              :5
Reco il brake      _ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --
Counterrecoil       mechanisms                                                                                       :7
Count rrecoil       buffer                                                                                           :8

          35. GENERAL.       _ A recoil    system is a m chani'm      which li it
a;ld controls   the recoil and counterrecoil     (see app. I) of a cannon. It . u-
~ ly consists    of three main components:       namely, a I' coil   rake, a coun-
 errecoil    mechanism,    and a counterrecoil     buffer.

  .       36. RECOIL BRAKE. _ a. General.            - A re oil rak i a m cha-
n\Sm which controls       the recoil of a cannon.     T     mo    rn roil    rak     i
~all "'d a hydraulic   brake and consists   essentially    of a iston which rlOV S
In a cylinder    filled with a fluid.   This liqui      is   ually oil an i'    alle
r   Cvu   oil.
           (1) The hydraulic              brake      is attached         to th      wpapon        in cith      r of two

r     . (~) The cylind ris attached to the cannon and mov >swith ilcluring
    cOlI and count rrecoil, while the piston is fixe to th carriage.

         (b) The piston is attached  to the cannon and mOV'5 with it during
~. coil and counterrecoil, while the cylinder    is fixed to the carriage.  (S(
 19. 31.) For the purpose of subsequent       discussion,   this  ?rticular  ar-
rangement        will be assumed.

           (2) In either          case,      when       the     cannon        recoils,        t.h r         is r laliv

OS 9-48
  36                       ORDNANCE SCHOOL

motion between the piston and the cylinder, and the operation in both cases
is fundamentally the same.



                      FIGURE 31. - RECOIL BRAKE.
         b. Operation. (See fig. 31.) - When the cannon recoils, it pulls the
piston with it to the rear. The oil to the left of the piston is under pres-
sure and is forced through holes provided in the piston. The resulting re-
sistance retards the recoil and brings the cannon to a stop. With this ar-
rangement of oil flow, the velocity of recoil would not decrease uniformly
and would result in unbalancing the cannon and carriage. To effect a uni-
form recoil, the rate of oil flow must be varied, or throttled, by varying
the size of aperture through which the oil flows. Several devices for
throttling the oil flow are described below.
        c. Throttling grooves. (Figs. 32 and 33.) _ Throttling grooves
are tapered slots or grooves cut into the recoil cylinder walls. In this
arrangement, the piston has no holes in it, and hence the passage of oil is

                                                             :rHROTTLING            GROOVE

                         OIL--   _
                                            --:;~:\~f,J                       '
                                            ,.       ,. \    ..,", ..",: ..",,1
     RECOIL CYLINDER'                  PISTON,              THROTTLING             GROOVE

                 FIGURE 32. - THROTTLING GROOVES.

                                                      OS 9-48



         FIGURE     . - THROTTLI       G GRO   VE'.

                         - 5-
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                       ORDNANCE   SCHOOL




              FIGURE    34. - THROTTLING   BARS.

                                                                                 OS 9-48

                FUNDAMENTALS                     OF ARTILLERY          WEAPONS      36

as t
through th e throttltng     grooves.      These grooves are cut in a mann r such
Lo 0 have the greatest depth at the beginning of recoil, the depth tap ring
th zoro at the end of recoil.         Thus. the oil flows freely at first, allowing
d cannon to recoil (fig. 33, A). As the piston moves in the cylind r, the
  CPthof groove is decreased         (fig. 33, B), resulting  in a corresponding          -
c: r ->ase in 01 fl ow and retardation
lhe '          '1                         of recO i1. At the end of recoil (fig. : • · <;:)
)'1 Piston completely       seals the cylinder.     thereby stopping th pas"ag         of
 I and bringing     the cannon      to rest.'
          ~. Throttling      bars.    (Fig. 34.) - Throttling    bars are w
vid ~tt ached, to the recoil cylinder walls, Rectangular
b aI'S                                                                  notch         .
At 1 d In the piston so that it slides on the throttling bars as thl           n r calls.
no;e     start of recoil. the notches formapertur            s thro ghwh'ch the oil an
     . (fIg. 31, A). The size of aperture           decreases      as lh cannon r coils
f urther (f Ig. 34.
s al               -!D.    until. at the end of reco il. the apertures
                                            .                              ar com let ly
brin d by the throttltng         bars (fig. 4. C). thus stoPPing th • flow of all and
      gmg th    cannon to rest.                       -
alt      £. Throttling  rod. - Tn this system.    a taper     throWing     ro is
    ached to the recoil cylinder.    The piston 1'0 is holloW lo rcc ive thl
ling       rod during recoil and orifices are provld    .'  In th   . ton to al-
rOw oil flow. The progre:stve       throttling of th flow of oil t, hown il
 19ur 35. At the start of recoil, the smallest     section of th lhrolllinr, n l

                              • THROT        TLI'    ROO

                                   AT       START    OF    RECOIL

                          -   --        -    -      -~        -_. -~   - -

                                    AT       END    OF     RECalL

                          l<'IGURE 35. - THROTTL                    G ROD.

                                                    - 7-
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     •    J
                                             ORDNANCE      SCHOOL

L JPpf)..,i 'th~ orifices, and hence the oil flows freely, allowing                                         the cannon
 a rf'C'oil.   A the cannon recoils    further,  the opening through                                         which the
0il an flow is ecreased,     until, at the end of recoil, the tapered                                        rod com-
plftely    s als th piston   orifices,   thereby   stopping the flow                                        of oil and
  ringing the annan to rest.

              £.   Variable    - In certain
                                   recoil.     heavy                             mobile weapons,    a variable
I,> gth of rp oil is employed,    permitting     long                            recoil at low angles of el('-
V'lt'0n to in"urE. ta ility, and short recoil at                                high elevation to prevent    the
ca non from       triking the ground.      (See fig.                             36.)   One type of variabl

                                                           LONG        REeOI..          7
                                                           (LOW        EL[VATIONV

                                                                  I'              /         oj
                                                                         -------,               1
                                                                          ---            "1.J

                                  FIGURE      36. - VARIABLE                    RECOIL

rpC'( '1 r, ('h'iI.i'IT, i illustrated   in figure 37. A hollow piston rod slides
()  1. rfJf tr)1 rori wh' ch has throttline-   grooves cut in it. Maximum    recoi 1
L;', ain< wb •.r. th' . ..,f ~r )Ove' line up with ports in the piston head, sine

                      Y   j   ,   ~l

                                                                                            THROTTLING   GROOVE

                                                           PISTON               HF AD

                     FIGURE            37. - VARIABLE      RECOIL                       MECHANISM.

                                                                               OS 9-48

a maximum flow of oil is then possible. To reduce the length of recoil,
the control rod is rotated, moving the throttling grooves out of line with
the ports. (For the purpose of illustration only one port and one throttling
groove are shown in fig. 37.) 'This action reduces the aperture through
which the oil can flow, and the increased resistance results in a shorter
         37. COUNTERRECOIL MECHANISMS'~ A counterrecoll mecha-
nism is a device which returns a cannon from its recolled position to its
in-battery position and holds it there untll fired again. The differenttypes
of mechanisms are described below.
         ~. Gravity type. _ The operation of this type of counterrecoll
mechanism is represented schematically in figure 27. When the cannon
is fired, it recoils rearward to its loading position, and a counterweight
is raised by the energy of recoll. After the cannon is loaded, the counter-
recoil mechanism is tripped, and the counterweight moves downward and
raises the cannon back into battery.        .
       ~. Spring type. (Fig. 38.) - (1) General. - The essential com-
ponents of this type of mechanism are a cylinder, spring, and rod. With

                                                   Pl5TON   ROO
                 COUNTERRECOft-   CYLINDER

                                   fiRING POSITION          (IN BATTERY)

                                                       sPRING     CQMPR£5S£O

                                  8.   AT    END    or      RECOIL


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                           ORDNANCE SCHOOL

the cannon in battery (fig. 38, A), the spring is under initial compression
and hence holds the cannon inplace until fired. When fired, the cannon
recoils, pulling the counterrecotlrod with it to the rear, and further com-
pressing the springas seen in figure 38, B. The spring assists in check-
ing the recoil. At the end of recoil, thespring expands and pushes the
rod forward, thus pulling the cannon back into battery and holding it there.

        (2) Hydrospring recoil system. - In this recoil system, recoil is
taken up by a hydrauUc brake, and counterrecoil is controlled by a spring-
type counterrecoll mechanism. The most compact arrangement is obtained
by a concentric grouping of brake, spring, and buffer (see par. 42), as
shown schematically in figure 39.

 BUffER                     CYLINDER              COUNTERRECOIL SPRING




        £. Hydropneumatic type. - As described below, a hydropneumatic
counterrecoil mechanism employs the force of compressed gas - usually
nitrogen - to return a cannon to its in-battery position from its recoiled
position. There are two general types of hydropneumatic counterrecoU
mechanism, namely: the direct-contact type and the floating-piston type.

        (1) Direct-contact counterrecoilmechanism.        (Fig. 40.) - In this
type, a counterrecoil cylinder is provided with a liquid-tight piston and is
connected, by a port, to a cyUnder above it which serves as a reservoir
for liquid and gas. The system is provided with liquid, sufficient to fill
the counterrecoil cylinder completely and the other cylinder about one-
half. In the case illustrated, the ptston is connected to, and recoils with,
the cannon. When the cannon is fired, liquid is forced by the piston through
the connecting port into the reservoir cylinder. This further compresses
the gas which was under sufficient pressure to hold the cannon in battery.
At the end of recoil, the gas pressure, acting in the opposite direction,
forces the oil back through the port against the piston, thereby returning
t!le cannon to its in-battery position and holding it there.

                                                                 as    9-48
                   FUNDAMENTALS   OF ARTILLERY       WEAPONS



                       FIRING POSITION    (IN   BATTERY)

                           AT END OF RECOIL


ty""    (2) Floating-piston counterrecoll mechanism. - A floating-piston
T~ie of counterrecoil mechanism is shown schematically in flgure 4~
ne ~ is a dependent type of counterrecoU mechanism, l.e., there is a con- .
A ~ ion between the hydraulic recoll brake and the counterrecoll cylinder.
co oating piston forms a tight seal between the fluid at one end of the
co~terrecoil    cylinder and the gas at the other end. As the cannon re-
th s, carrying the recoll-brake piston with it, the liquid is forced through
foe port into the counterrecot.l cyUnder, thus forcing the floating piston
Chrward and further compressing the gas. The gas pressure assists in
Pi:t~king the recoiL At the end of recoll, this pressure forces the floating
th n backto the rear, driving the fluid back through the port and against
baekrecoil-brake piston. This pushes the piston, and hence the cannon,
th c Into battery. The initial gas pressure is made great enough to hOld
  e c~non in ba~tery untU it is fired again.

OS 9-48
                            ORDNANCE SCHOOL

                   RECOIL   CYU!lVER


                   FIRING POSITION            (IN   BATTERY)


                            AT   END OF RECOIL

        38. COUNTERRECOIL BUFFER. - a. General. _ A counterrecoU
bUHer is that part of a recoll system whtch controls the last movement
of a cannon in counterrecoll.    Its purpose is to prevent shock as the can-
non returns to its firing position.

         ~.. Dash-pot buffer. (Fig. 42.) -" A dash-pot counterrecoU buffer
consists of a tapered rod {buffer rod) whtch is attached to the counterrecoU
cylinder and which slides in and out of a cyHndrical cavity, or dash pot,
in the end of the piston rod. In this particular     case, the counterrecoU
cylinder is attached to the cannon and recoils with it, while the piston rod
is attached to the carriage and does not move. As the cannon recoils, the
buffer rod is withdrawn from the dash pot, which then fills with oil. Dur-
lng the latter part of counterrecoU,    the buffer rod enters the oU-filled
caVity, and the escape of oU from inside the dash pot is permitted only
through the narrow clearance between the rod and dash pot. The pro-
gressively closer fit of the rod in the dash pot allows the oU to flow out

                                                                                         o    9-48
                   FUNDAMENTALS            OF ARTILLERY             WEAPONS

~~ro~gh only a small orifice,    and the motion of the buffer rod in the last
is W lllches of counterrecoil meets with great resistance.   The cannon thus
    eased into battery without jarring the carriage.

                                COUNTERRECOIL    CYLINDER

                                                              AT    END    OF   RECOIL
            AT    ST ART   OF   RECOIL

                           FIGURE 42. - DASH-POT              BUFFER.

n I      ':.. Internal-rod buffer. - Figure 43 show one deslgn of an int 1'-
i: bUffer. Essentially, it consists oia tapered rod (throttling ar), which
int:~tached to a floating piston and which moves relative to a sl cv , the
c     lor of whIch has tapered throttling grooves. Wh n I' COliha h en
hompleted, the floating piston has been p shed to the right, an hair
t~S been compressed. Then during counterrecoil\h      air pr    ur a t on
th~ floating piston which moves to the left, forcing th oil through th
   ottltng       grooves   as indicated.        As counterrecoil          rogressAS,     the hea



                                                       THROT TUNG    GROOVE

                      FIGURE 43. _ INTERNAL-ROD                     BUFFER.

OS 9-48
  38                      ORDNANCE SCHOOL

on the throttling bar gradually diminishes the area of the throttling
grooves through which the oil flows. The resulting resistance eases the
cannon into battery without shock.

        ~. Respirator (Schindler Buffer). (Fig. 44.) - Though not a true
counterrecoil buffer, a respirator may assist buffer action. This device
Is employed In a hydropneumatlc recoil system as indicated In figure 44.
The respirator is screwed into the front end of the recoil cylinder. It
contains a one-way air valve which opens to pressure from the outside only.
During recoil, the rearward movement of the piston causes air to be drawn
into the respirator through a hole "A" and then into the recoil cylinder
through a hole "B",the valve opening to permit this passage of air. During
counterrecoil, the internal air pressure closes the valve. The air, now
compressed by the returning piston, is permitted to escape only through
a hole "C" of a predetermined size. The resulting resistance to the escape
of air produces a buffer action.

                                    RECOIL   CYLINDER


                             DURING RECOIL

                               VALVE (CLOSED)

                          DURING COUNTERRECOIL

           FIGURE 44. - RESPffiATOR (SCHlliDLER BUFFER).

                                                                                    os 9.48
                    FUNDAMENTALS         OF ARTILLERY          WEAPONS

                                      SECTION III

   Ge                                                                             Paragraph
., Ac~eral                                          --------   ---- - --- -----           39
  S      On                                ---------------~----------                    40
   J:,ring equlllbrator        ~          --       -- -- -- --------------               41
   P eumatic equilibrator                --- -- __-----:----    ------- --- -            42
     neumatic-spring equilibrator                                                        43
  ab      39. GENERAL. - In modern artillery weapons, the hOrizontal axis
  th out which a cannon revolves in elevation is located well to the rear of
  t e center of gravity of the cannon. The cannon thus is unbalanced and
  ~~dS to Up forward. An equlllbrator is a device whlch overcomes this
  tl alanced weight and keeps the cannon in balance at all angles of eleva-
   on. There are three general types of equilibrators: namely, spring,'
   Pneumat'lC, and pneumatic-spring.
   w          40. ACTION. _ An equlllbrator          may act to balance an artillery
       eapon in either of two ways:
   of         !':. By pulllng downward on the breech end of the cradle, rearward
   fl the trwmlons.      This type of equlllbrator        Is known as a "puller"        (See
       g. 45.).

   fa         ~. By pushing upward on the tipping part, or cradle, of the cannon,
   r    7ard of the axis of revolution (trunnions). This type of equlllbrator is
       e erred to as a ''pusher.'' (See fig. 46.)


                  FIGURE 45. _ SPRING EQUILffiRATOR                (PULLER).

OS 9-48
 41-43                     ORDNANCESCHOOL

        41. SPRlliG EQUILIBRATOR. - One type of spring equilibrator
(pusher type) is illustrated in figure 46. Two such units are provided, one
on each side of the carriage. Essentially, the mechanism consists of two
telescoping sleeves forming a housing for a spring which is under initial
compression. With the cannon in its horizontal position, the telescoping
sleeves are pushed together, compressing the spring, and the resultant
pressure upward against the cradle balances the cannon. As the cannon
is elevated, less force is required to hold it in balance. The outer sleeve
moves upward, allOWingthe spring to expand, and thereby reducing the
upward force, which is always just great enough to hold the cannon in

             FIGURE 46. - SPRlliG EQUILIBRATOR (PUSHER).

          42. PNEUMATIC EQUILIBRATOR. - A pneumatic equilibrator
  operates similarly to a spring equilibrator, as outlilledabove. The system
  consists essentially of two gas-filled telescoping cylinders, with suitable
. packing to confine the compressed gas. The compressed gas stores up
  the energy necessary to balance the cannon in the same manner as does
  the spring in the spring equilibrator.

         43. PNEUMATIC-SPRING EQUILIBRATOR. _ A pneumatic-spring
 equilibrator is a variation of, and functions essentially the same as, the
 pneumatic equiUbrator. The main difference between the two is that the
 former has a retarding spring which comes into action at extremely high
 angles of elevation. At high angles of elevation, the unbalanced force of
 a cannon may be reduced so much that the initial pressure in the equiU-
 brator would prevent the cannon from being depressed. Before this con-
 dition occurs, the retarding spring counteracts the air pressure in the
 equilibrator, thus keeping the cannon in balance.

                                                                             OS 9-48
                FUNDAMENT          ALS OF ARTILLERY        WEAPONS

                                       SECTION IV
                 SUPPORTlliG         MEMBERS        OF THE CANNON
G                                                                       •   Paragraph
s~neral                                                     --------------          44
C elgh                                   --- --- -- ---- -- -------- ---- -         45
Tradle                                                         ------------         46
 op carriage                                                                        47
B ottom carr iage                                   -------------------
                                                           .'~.                     48
rl      44. GENERAL. _ The main cannon-supporting members of a car-
I age are: the sleigh, cradle, top carriage, and bottom carriage. Depend-
~g upon the design of the carriage, certain of these components mayor
    ay not be used.
    h   45. SLEIGH. (Fig. 47.) - The sleigh is that part of a carriage
W  ich forms the immediate support of a cannon. In practically all of our
cannon, the sleigh houses the recoil mechanism and recoils with the bar-
~~l on the cradle. In some cases, the recoil cylinders are bored directly
r~ ~ the sleigh; in others, the cylinders are separate tubes which are
W:i,dly attached to the sleigh. The cannon is firmly secured to the sleigh
    ch, in turn, slides on the cradle in recoil and counterrecoil.

                                 FIGURE 47. - SLEIGH.
W . 46. CRADLE. (Fig. 48.) -The cradle Is that part of the carriage
h hlch supports the cannon and sleigh. Where no sleigh is used, the cradle
w~~es the recoil mechanism. In general, the cradle is aU-shaped trough
    ch has slides or roller paths along which the gun recoils in firing. It

                        v' ..   > ...••••....~-'    15Piston rod
                      ~~~1!li.~#(j;';;~                locked to cradle

                 Cradle                   :rrunnion

                                 FIGURE 48. - CRADLE.

OS 9-48
 46-48                     ORDNANCE SCHOOL

provides means of securing the recoil piston rod or rods where a sleigh
is used, and provid€s mountings for the recoil cylinders if no sleigh is
used. It has trunnions which furnish an axis about which the cradle, and
hence the cannon, rotates in elevation.     The trunnions rest in trunnion
bearings on the lower part of the carriage.    Runways on the cradle form
surfaces upon which the cannon or slei~h recoils directly to the rear.

         47. TOP CARRIAGE. (Fig. 49.) - The top carriage, when present,
supports the cradle in its trUlUlion bearings and carries the elevating
mechanism. It moves with the cradle in traversing,      but not in changes of
elevation.   In traversing (rotating in a horizontal plane)" it pivots on the

                                       Trunnion      bearing


                     FIGURE 49. - TOP CARRIAGE.

axle or bottom carriage.    In cases where a top carriage is not used, its
function is performed by the upper front par:!: of the trail (see par. 61).
In general, a top carriage is required when pintle traverse is desired (see
par. 54).

        48. BOTTOM CARRIAGE. (Fig. 50.) -The bottom carriage is that
part of the carriage assembly which supports the top carriage and has at-
tached to it portions of the mechanism for rotating the top carriage with
respect to the bottom carriage.   The pintle may consist of a vertical pin
or bolt. In mobile mounts, the bottom carriage may have the trail end
(or ends) attached, and sometimes a firing jack (fig. 79) may also be at-
tached; the bottom carriage may be fixed to the axle, or it may replace
the axle and carry the Wheels.

                                                                       OS 9-48

                                 Bottom .carriage

                     FIGURE 50. - BOTTOM CARRIAGE

                                SECTION V.

G                         E LEVATrnG MECHANISMS                       Paragraph
Teneral                                 ------ - --- -- -- -- -----           4
 onstruction .___________________________________________                     50
d        49. GENERAL. - a. An elevatlng mechanism (flg. 51) consls
tlelllces for placlng and holding the axis of the bore at a desired Incllna-
    on to a horizontal plane.

                   FIGURE 51. - ELEVATrnG      MECHANISM.

OS 9-48

        b. Inorder that a projectile fired from a cannon may reach a given
target, the cannon must be laid, or aimed, with a predetermined angle of
elevation (quadrant elevation) .. This angle is composed of two elements
(see flg. 52).

        (1) The angle of elevation applied to the piece to give the hori-
zontal range to the target (range elevation).        '

        (2) The angle which must be applied to the piece to correct for the
difference in altitude between the cannon and the target (angle of site).

      \.h4! algebralc 8um           Angle of elevallon applied to
      or the elevation              pl4~ce to qive horiz.ontal range .ELEVATION ,
      and the sile

     ~~                 Horhontal     range-

                                               Angle   which   must:. be applied
                                               to piece lo correct for difference
                                               in elevalion    of gun and l.arget   &

                                                     ANGLE      OF SITE..


        50. TYPES. - Elevating mechanisms are divided into three general
types or systems according to the line of sighthlg and its relation to the
angle-of-site elevating mechanism and the range elevating mechanism:
namely, dependent, independent, and semi-independent.

         ~' Dependent line of sighting. (Fig. 53.) - A dependent line of
sighting is one in which the weapon is laid for angle of site and for range
by a single elevating mechanism; any movement of the elevating mecha-
nism moves the cannon and the line of sighting simultaneously.       On the
particular design illustrated, the angle-of-site level and the telescope
are attached to the movable part of the range or elevation scale. Hence,
any setting on the range scale will result in a corresponding movement
of the angle-of-site level. The angle-of-site level is provided with a site
scale on which the angle of site can be set. Movement of the site scale
moves the axis of the level with relation to the line of sighting, while
movement of the range scale moves both the axis of the level and the line
of sighting simultaneously.     Thus, the elevating mechanism handwheel
moves the follOWingparts as a unit through a vertical arc: cannon tele-
scope (line of sighting), angle-of-site level and scale, and range or ele-

                                                                     OS 9-48

vat'IOn scale.  The proper elevation Is set as   follows: The angle of slte
 s set on the site scale and the range is set     on the range or elevation
~cale. The elevating handwheells then turned     until the bubble Is centered
 n the level. The cannon is noW properly laid    for elevation.

                 FIGURE 53. _ DEPENDENT    LINE OF SIGHTING.

 sl       ~' Independent line of sighting. (F ig. 54.) - An lndependent Une of
 b ghtlng Is one In which the weapon is laid for angle of site and for ,ange
 / two dlstlnct and Independent elevatlng mechanisms; a change In laylng
 tor range does not aifect the laylng for angle of site. and vice versa. Thls
  ype of elevation-laying   mechanism requires an additional part for the
 Carriage, whlch is known as a rocker and is lnterposed between the cradle----
 and the bottom carriage or trail      The telescope and angle-of-site elevel
 are att ached to, and move with, .the rocker. Movement of the angl - -
 ~lte handwheel thus moves the cannon, rocker, site scale and bubble, and
  elescope; movement ofthe range elevating handwheel moves only the can-
 non with respect to the rocker, without moving the other parts. The pro-
 ~~r elevation Is set as follows: The angle of site is set on the angle-of-
    te scale, and the bubble is centered by turning the angle-of-site hand-
 ~heel. The range elevatlon is then set off by means of the range elevatlng
   andwheel which moves the cannon with respect to the rocker. To attain
 the same result, these two operations may be made in the reverse order;
  Le, range elevation set first and angle of site set next.

OS 9-48
                       ORDNANCE SCHOOL

                                         :Rt!!!Il2.f~ ~levatm~
                                     ~             mecks12i.sm
                                     I   ~at~-of.site       elevatina

          FIGURE 54. - INDEPENDENT   LrnE OF SIGHTrnG.

                                                                     OS 9-48

 i       ~. Semi-independent Une of sighting. (F i g. 55). - A semi-
  ~dependent line of s ightlng is one in which the cannon is elevated for both
 ~tte ~d ;-ange by a single elevating mechanism, as in the dependent type.
 d is stmllar to the independent type in that a change in setting for range
 t:es not affect the setting for site, and vice versa. On the design shown,
 vae,angle-of-site mechanism', the telescope, the range disk, and the ele-
. hon micrometer worm are mounted on the same bracket. Hence, any



                               ORDNANCE SCHOOL

 movement of this bracket (to level the angle-of-site
                  movement of these parts.
                                                            level) results in a .
                                                Thus, when the angle-of-site

 leveling worm Is moved, the adjustable index is moved away from the             j

 fixed Index. Also, a setting on the elevation or range scale further moves
the adjustable index out of alignment with the fixed index. The fixed
 Index, which is on the cannon, is brought into alignment with the adJust-       j
able Index by turning the elevating handwheel which moves only the can- l
non with respect to the other parts.      The proper elevation is set as fol- l
lows: . The angle of site Is set on the angle-of-site      scale, moving the ,
bubble out of level. The bubble is then leveled by means of the angle-of- .
site worm, which moves the entire bracket, thus moving the adjustable            ,I

index away from the fixed index. The range is then set off by turning the,
elevation-micrometer      knob, again moving the adjustable index with re-
spect to the fixed Index. This last operation does not affect the setting
of the line of sighting, the angle of site, or the level bubble. Finally, the
cannon Is moved by means of the elevating handwheel until the fixed index
coincides with the adjustable index, and the cannon is properly laid for
elevation.   This latter movement does not affect the setting of the tele-
scope or bracket, nor do these parts move when the cannon is elevated
or depressed.     The fixed index is the only element which moves with the

         51. CONSTRUCTION. (Fig. 56.) - The mechanical means of ele-
vating a cannon may be one of two main types: namely, rack-and-pinion,
or screw. Generally, for the independent line of sighting, a double rack-
and-pinion (or double rack-and-worm),    a double screw, or a combination
of rack-and-pinion   and screw is r€quired.   For either the dependent or
semi-independent   systems, a single screw or a single rack-and-pinion
with Worm Is used. For greater strength, many of the heavier carriages
and some of Our newer carriages have two parallel racks and two pinions,
one rack and pinion being on each side of the gun.

         a. Rack-and-pinion    elevating mechanism.     _ The rack-and-pinion
type of elevating mechanism consists of an are, called the rack or seg-
ment, which moves or can be moved by a small spur gear, called the
pinion. The rack may be attached to the tipping parts and the pinion to
the fixed part of the carriage, or vice versa. Whenever a rack-and-pinion
is used, a worm and a worm wheel must be placed in the gear train to
make the system irreversible,      that is, make it hold its position when the
handwheel is released.     In Some cases, a worm and a segment of a worm
wheel are used instead of rack-and-pinion
                                                with worm in the gear train.
                                                              • t': ....
                                                           I ~, .     "I   ~

        !?. Screw-type elevating mechanism. _ The scre~-type elevating
mechanism consists essentially of a screw and nut betwel=m the tipping
parts and a fixed part of the carriage.   The mechanism is actuated by a
handwheel and suitable gears.     Either the screw or the nut may be at-
tached to the Upping parts.

                                     OS 9-48

OS 9-48
 52-53                    ORDNANCE SCHOOL

                              SECTION VI

                      TRAVERSING MECHANISMS
General ---------------------___________________________                 52
Axle type ----------------------_________________________                53
Pintle type --------------------_________________________                54 .
Base ring and racer type --------.-_______________________               55

        52. GENERAL. - a. A traversing mechanism (fig. 57) is a device
for making internal changes in the direction of the axis of a cannon bore.
The moving parts may cons ist of only the cannon and the upper part of the
carriage, or in some cases, the moving parts may consist of the entire
cannon and carriage except the axle (see par. 58). In the case of self-
propelled artillery and certain types of railway artillery, the entire ve-
hicle or railway car may be moved to traverse the cannon (see fig. 29).

        b. Traversing   mechanisms    are   of three   general types:   axle,
pintle, and base ring and racer.


                FIGURE 57. - TRAVERSING MECHANISM.

          53. AXLE TYPE. (Fig. 58.) - a. General. - In this type oftravers"
 ing mechanism, the upper part of the-carriage and the cannon are moved
 laterally along the axle, pivoting about the trail spade. This arrangement
 is applicable only to carriages with box trails.

         b. Construction. - The mechanism may consist of a threaded axle
 and traversing nut (fig. 59) or of a separate traversing screw and nut (flg.
 60), togetherwith the necessary gear train and handwheel. Either system
 is irreversible,  so that the only purpose of additional gears is to change
 the power ratio or the direction of the power applied at the handwheel.

                                                          o   9-48

Jr~~-~ x::::.-::.-=.-.-   -~

as 9-48                                                                         I
 53-55                    ORDNANCE SCHOOL                                       I
The threaded-axle type is simpler than the threaded-screw-and-nut
but is suitable only fo light carriages.
                                                                       type;    I


    FIGURE 60. - AXLE TRAVERSE WITH SEPARATE TRAVERSING                             I
                        SCREW AND NUT.

          54. PINTLE TYPE. - a. General. - In the pintle type of traversing         I
mechanism, the cannon is moved about a vertical pivot fixed on the axle             I
or on the underpart of the carriage (fig. 61). It can be used with all types
of trails, and it is the only type suitable for use with the split trail car"
        b. Construction. - The mechanism consists of a handwheel and a              I
shaft which operate, directly or through a train of gears a worm and                I

rack, or a pinion and rack (see fig. 62). As with the elevating mechanism,          I
some type of irreversible gear, such as a worm and wheel, must be in..              I
eluded in the system to prevent movement of the gun when the handwheel
is released. The handwheel may be attached to the traversing parts or to                I
the flxed parts of the carrIage.                                                    I
         55. BASE RING AND RACER TYPE. (Fig. 63.) - This type of
traversing mechanism is used on most heavy-caliber cannon which are                     1
mounted on barbette carriages.    Essentially, the mechanism consists of                I
a very large roller bearing with rollers operating between two bearing
surfaces:    namely, the base ring and the racer. The base ring is the                  I
lower bearing surface, and the racer is the upper bearing surface.    The
main frame of the carriage is bolted to the racer and rotates with it. In"
side and concentric with the base ring is mounted a circular traversing'

                                                              os 9-48

~ack. A spur pinion, meshing with this rack and connected to the main
 rame of the carriage, traverses the cannon under the acUon of a trav-
ersing crank.


OS 9-48
  55                   ORDNANCE SCHOOL


                       -------lI     I

                                     I {"".
                                                   "oJ •
                                     ~ "oJ

                                     \f\/                  '

                                         Top corriog_



                                                                   OS 9-48

                                 SECTION VII

 ~eneral                                  ---------------------paragra~~
 Axle for axle traverse                                                  57
 AXlefor pintle traverse          ,____________________________          58
  xle for sprung carriage                           ------------
                                                  ...                    59

, Su      56. GENERAL. - An axle (fig. 64) is that part of a carriage which
 di pparts the weight of the carriage and the cannon, and has on lts ends,
 rnrectlyar indirectly, spindles upon which the wheels are mounted. It
 ei~ carr! connections for the trails and brakes. Axles are of steel,
 fa er sahd or tubular. There are tnree main types of axles, classified
   r Convenience of discussion   as follows:

        a. Axle for axle traverse.

        b. Axle for pintle traverse.

        c. Axle for sprung carriage.

                            FIGURE 64. - AXLE.

  dri     57. AXLE FOR AXLE TRAVERSE. (Fig. 65.) - This type is cylln-
  geaCal a~d has bearings on which the carriage, actuated by the traversing
  aXl:' shdes or rolls in traversing.     The axle, or a sleeve around the
  Plai' rnay be threaded to receive the traversing gear. or the axle may be

  ~~~~l:~~:s f~~:h;r~~~~~~~~~~{l; ~;a;:::i~:~~;:;~:,         a~~e;re~e~:t~:
  taper n of the axle on the carriage.    The ends of the axle either are
       ed to form a spindle, or are formed so as to receive a wheel carrier,

OS 9-48
 57-59                     ORDNANCE SCHOOL

that is, a bracket which is attached to the axle and carries   a wheel spindle
on its outer portion.

               FIGURE 65. - AXLE FOR AXLE TRAVERSE.                               I
        58. AXLE FOR PlNTLE TRAVERSE. (Fig. 66.) 7 This axle may                  I
be cylindrical, of built-up section or of I-section, and may be dropped in.       I
the center to lower the center of gravity.      The wheel spindles may be
separate pieces set in a housing which forms the center section of the             I
axle; they may be an integral part of the axle; or they may be attached            I
to wheel carriers which, in turn, are secured to the ends of the axle. The
pintle socket is secured to the axle as shown, or it may be secured to the         I
bottom carriage which is fastened to the axle. The bottom carriage may
be used to replace the axle, by faster.ing wheel carriers to the outer por...
Hons of the bottom carriage.


   Trail bracket

              FIGURE 66. - AXLE FOR PlliTLE TRAVERSE.

         59. AXLE FOR SPRUNG CARRIAGE. - a. In some carriages,              for
transport,   the weight is transmitted    to the axle through springs; while,
for firing, the weight rests directly on the axle. This type of carriage
is known as a sprung carriage.      Figure 67 represents one type of axle for
a sprung carriage.     The multiple-leaf    spring is attached at its center to
the bottom carriage and is suspended by detachable shackles underneath
the axle. In traveling, the weight of the carriage        is transmitted to the

                                                                  OS 9-48

~le through the springs, thus reducing road shock. In the firing position,
 he spring is unshackled, permitting the bottom carriage to rest directly
upon the arched central portion of the axle.
        b. A sprung carriage may also be obtained by using spring wheel
carriers on the axle ends; one wheel carrier is secured to each axle end,
~d  v:heel
           spindles are assembled to the carriers. This type of construc-
 On ts similar to the independent suspension used in automobile con-


                               SECTION VIII

                                  BOGIES                         Paragraph
             ________________________________________________            60
 c        60. GENERAL. _ A bogie is a strongly bullt cart which is used on
 t ertain artlllery weapons for the purpose of supporting the weapon during
 iransport.     When the weapon is emplaced in the firing position, the bogie
 t~ eith~r removed or so adjusted that it no longer supports the weight of
 o e weapon. Depending upon the particular design of the mount, either
 sn~ Or ~o bogies may be used to transport a weapon. Figure 68 shows a '---
 t~ emallc representation of a weapon using two bogies for transport.       In
 twe trav.e1ing position, the weight of the entire weapon is supported by the
  a ~ bogies, the forward bogie being connected to a prime mover through
  u unelte. For emplacement in the firing position, the weapon is jacked
  /i~o that its entlreweight is lifted from the bogies. The bogies are then
  ~",d out from under the chassis and the weapon is lowered to its firing
     tHon on the ground.

OS 9-48
  60                  ORDNANCE     SCHOOL



                     Z                            8-
                     0                            rn
                     t-                           f:l
                                            Z     t)
                     U)                     0     ~
                     0                      t-
                     a.                           ~
                     C>                     0     ~
                     Z                      n..   :>
                     -I                           =s
                     w                      C>    ~
                                            Z          I
                     ~                      0::
                     a::                          ex>
          101        t-                     r:    co
          i                                        ~

                     FUNDAMENTALS             OF ARTILLERY       WEAPO

                                         SECTION         IX

                         TRAILS,     OUTRIGGER           , A 0 SPADES    ParapTa    h
Trails                                                                              1

f         61. TRAILS, _ A trail is that part of a carrlag      through which th
  o~ces of recoil which are not taken up by the recoil m cl ani. mart> tran -
mltted to the ground.     The trail stabilizes     the w apon an k          it from
mOving out of its original    firing position.    It also serves to connt t th
:veapon with its prime mover for transport.          Th forwar     en of th trail
 IS fastened  to the axle or to the lower portion of th         arriage;   and, the
rear end has a spade attached thereto.         Trails ar of two        n ral lyp s:
namely,      split   trails   and boX trails.

tia       ", Split tral Is, (F Ig, 69,) - A slit trail Is 0 n pose of two .:
   ns, each attached directly or mdlreetly        to th axl or boltor      . rrt gl
near the wheels.       For transport,   th section     ar locke tOf th( r at lh
rear end; for firing, they ar separate         as far as permilt d by the wh(>(1.
or. trail stops.    Usually, a split trail is mad      of box     lion. whicl    i 1'-

;n1nat In trail spades,      For traveling a luneUe (-, l ar, ': a) i ' "U' (') ,
 ~ one trail     nd, and a lock is fiU d at the two >nds to holl-U,       I ,'1 1)-
 eth r, An equaliz 'r (see par, 64) or a fir'ng "CK (: , par, ,'7) ;: 'I," '
    o aid ir: stabilizing     the carriage.

                                  FIGURE        '9. - , PLIT TR/.IL.

          ORDNANCE      SCHOOL


                OPENING IN TRAIL


                  FUNDAMENTALS             OF ARTILLERY                WEA PO :3

  ,     b. Box trails.  _ A box trail is one whi h is COlT.pos' ( of a ~;inP"l('.
rtgid, built-up member.     In all type of box trail.    th traver:(      or U1(
~arrlage must be comparatively     small in or or Lo I  n c;L, illLy II fll'inv,
 n most cases,  the front ends of the si e lat      an ,,-xt, n i( 'lpW' nand
~re provided with bearings    to recelv   th                    fh, t )'(, main
 ypes of box trails are described'      e10w.
           (1) Simple box trail.  (F ig. 70.) - A si    1e 1 YX t '3.'1 is con po.'( 'i
essentially    of two side plates joined together    y tra . v rs( ri )~) or tran-
~oms, a Lop plate, and a spade, Th sl <' I tes xL>' i               ,r 1 hI' 'P u['ll
 : Support the cannon so that, when th cannon l' )i1 at (xt r'f P,I (1, v< -
bon,   it will clear   the trail.
         (2)Tubular  trail. - This is sim ilar to th
~hat the main portion of the trail consist     of a p'                                 ro , ,', ctio                    1

IS tubular.
,         (~) Mod Ifled box Lrall.       (Fig,    71.) - Th'>     If   0   Iif",                          '   t I',    II
;s a variation     of Lhe simple box trail.   Th chi' f [ if          "               !I.
 WO types IS that the modified      boX ty     provl1 SaIl       P( 11['" ll1 th(  ,.. i 1
through which the cannon recoils.         Th'  arrai-r,'rI,E'I,t il cr' a.'( "th  lit -
rnissible    1 vation of the annon, but tr v rc;e i' ,till (II pa atiV. ';,. ," . 11.
,         6~, OUTRIGGER         ' _ An    oulrl Vcr n: '1.1 I. can ,', r t'                                   t .. ,   'I
In .that it aids in stabilizing   a w     apon and irl tran I itt" I -r it  r",'   I   ..                        rt-

co: 1 to th ground.      The type of      outriff"er   she w n ,I' !" 1: io' r              l             I
Pnmari ly in railway arlill        ry,    wh\ lL tht:' tyP( ll'1S rat I i' .                    j   ,-,

 Used mainly     in antiaircraft    artillery,

               FIGURE     72. _ OUTRIGGER               , RAILW        Y ARTILLER               '

().~ !J-48
                                     ORDNANCE         SCHOOL

             f I   URE 7:~. - OUTRIGGER.            ANTIAIRCRAFT              ARTILLERY.

                                             LUNET TE   (FIRING   POSITION)

      LU E T TE
          (TRA Ell G    pas, TIC


                      PI TLE OF PRIME       MOVER

                                   FIGURE    71. - FIXED     SPADE:.



       FIGURE   7~. - HIl'.GED L)PADE.

OS 9-48
 63-65                       ORDNANCE SCHOOL

        63. SPADES. - A spade is the end of the trail of a weapon, which
is forced into the ground to prevent movement of the weapon during re-
coil. The three main types of spades are described below.

        ~. Fixed spade. (Fig. 74.) - A fixed spade is one which is rigidlY
fastened to the end of a trail. It may be a forging, a casting, or of built-
up construction.   The fixed spade shown in figure 74 has a movable lu-
nette attached. The purpose of the lunette is to connect the weapon to its
prime mover. In the firing position, the lunette is turned up so that the
spade can be driven into the ground. In the traveling position, the lunette
is turned down and the eye, or ring, is dropped over the pinHe of the prime .
mover. With the lunette in this position, the trail is raised so that it ~,
clears the ground.

        b. Detachable spade. (Fig. 75.) - A detachable spade is one which                    "
is detached from the trail end for traveling and is assembled thereto for
firing.                                                                                      I
         c. Hinged spade. (Fig. 76.) - A hinged spade is 8J modification of
a detachable spade. In this type, the spade is hinged to the end of the                          I
trail and can be adjusted to aposition suitable forthe type of ground. For
traveling, the spade is folded underneath the trail.

                                     SECTION X                                                   I
                                   E~AL~E~                                                       I
General                                                                    Paragra~~             I
Types of equalizers     -------------------------------------                       65
          64. GENERAL. - An equalizer is a mechanical device which per-                          I
mits the four points of contact with the ground - the two wheels and the".,
two trail ends - to be in different planes. That is, it compensates       for
 irregularity of the terrain, so that the weight of the weapon and the shock
of firing are transmitted     to the ground through all of the four points.
Several types of equalizers are found in our service, as described below,

          65. TYPES OF EQUALIZERS.         (Fig. 77.) - a. The equalizer shown
Ln A, consists of a horizontally-pivoted  support which rotates in vertical gib
bearings.   This rotation is in a vertical plane parallel to and in the rear
of the axle. The support has a pintle secured to its center, and the trails
are attached to its ends. The unevenness of terrain is offset by raising
or lowering one trail or wheel and thus rotating the support about its
pivot. In the traveling position, the front ends of the trails overlap rampS,
on the axle, thus locking the support and axle together.

          b. B and C show two equalizers            which function in essentially   the

                                       OS 9-48


OS 9-48
 65-68                     ORDNANCE SCHOOL

same manner. In 1:?oth these types, an equalizer bar, fixed to an ex"
tension of the pintle, rotates in a plane parallel to .the axle. By moving
the trails, the position of the equalizer bar is controlled through equalizer
arms which rotate about the axle. The chief difference between these two
types lies in the method of connecting the arms to the bar. In the former,
case (m, universal joints are employed, whereas in the latter (~), mating
gear segments are used.

                                SECTION XI

                            FIRING SUPPORTS
General ---------------------___________________________                 66
Firing jacks -------------------                              ~__        67
Firing segments ---------------_________________________                 68     I

         66. GENERAL. - The shock of firing tends to raise a light mobile
artillery weapon from the ground causing it to bounce out of position. In
order to reduce this tendency, it is necessary to raise t,he wheels clear
of the ground and to support the carriage on more stable firing supports.
The two main types of such firing supports are des'cribed in the following

        67. FIRING JACKS. (Fig. 78.) - A firing jack is a device which, Ij
during firing, provides a single support for that portion of the w~ight of~,
the weapon normally carried by the two wheels. This results in a three- }'1
point support, one point of contact being the firing jack and the other two ;
points being the spades of the trail.                                        ,

          FIRING JACK                                              SPADE

                        FIGURE 78. - FffiING JACK.

       68. FffirnG SEGMENTS. (Fig. 79.) - A firing segment is in effect
a segment of a metal wheel, which is mounted on the axle alongside of

                                                                 OS 9-48

each carriage wheel. The radius of the segments is slightly greater than
the radius of the wheels. Hence, when the segments are lowered, the
wheels are raised clear of the ground. This results in four points of
~u.pport _ the two segments and the two spades. In the traveling position,
the segments are rotated upward.


                    FIGURE 79. - FillING SEGMENTS.

OS 9-48                                                                          -I
                            ORDNANCE SCHOOL
                                APPENDIX I


        AMMUNITION, TYPES. - According to the method of assembly
and the manner of loading into the cannon, ammunition is classified into
three main types as follows:

        a. Fixed ammunition. - This type comprises       a cartridge case
(which contains the propellant) whose base contains the primer, and whose
forward end is crimped to the projectile so that the entire round is inte-
gral and all components are loaded into the cannon as a unit.

        b. Semiflxed ammunition. - This type differs from fixed ammu-
nitlon in that, while the projectile and cartridge are issued assembled
and are load'ed into the cannon as a unit, the cartridge case is not perma-
ently attached to the projectile, but may be removed from it at the firing
point for the purpose of varying the amount of the propelling charge.
         c. Separate-loading  ammunition. - This type is ammunition in
which the round consists of a primer, a propelling charge, and a pro-
jectile, each of which is separately loaded into the cannon.

        CALIBER. - The caliber oI a cannon is the diameter of the bore,
usually in inches, measured between the lands. (See fig. 6.) The term is
employed in two ways:

          a. "CaUber .50" defines a cannon whose bore diameter    is .50 inch.
        b. "50-caliber gun" indicates a gun whose length, measured from
the front end of the gun to the front face of the powder chamber, is 50
diameters; e.g., a 14-inch, 50-caliber gun is 700 inches long (14 x 50 = 700).

        CAM. - A cam is a moving part whose surface either imparts
motlon to, or receives motion from, another part by sliding contact .. F ig-
ure 80 shows a rotating cam imparting motion to a rod which is in contact
with the cam surface. Figure 81 illustrates the up-and-down motion re-
ceived by a projecting cam from a horizontally moving bar.

        COUNTERRECOIL. - Counterrecoil is the movement of a cannon
from Its recolled position to its in-battery position.

        EROSION. - Erosion is the gradual wearing away of the bore of a
cannon - especially the lands - due to firing. It is evidenced by a rough
and enlarged bore resulting in a loss of range and accuracy.

       IN BATTERY. - A cannon is said to be in battery when it is in its
normal or firing position. (See fig. 40.)

                                    OS 9-48




OS 9-48
                          ORDNANCE SCHOOL

        MUZZLE VELOCITY. - Muzzle velocity is the rate of speed, usu .. I
ally expressed in feet per second, with which a projectile leaves the muz" ,
zle (forward end) of a cannon.

        PRIMER. - A primer is a device for igniting the propelling charge
of a round of ammunition. In separate-loading  ammunition, the primer is
separate from the round, and is inserted into an opening in the breech"
block. (See fig. 23.)

        RECOIL. - The recoil of a cannon is its backward    movement due
to the forces of discharge. (See fig. 40.)

        SUBCALIBER CANNON. - A subcaliber cannon is one of smaller
caUber which is used for target practice in conjunction with a larger can-
non for the purpose of reducing the expense of ammunition.      There are
two types of subcaUber cannon: namely, subcaliber gun and subcaliber

        ~. Subcallber gun. (Fig. 82.) - A subcaliber gun/is a gun which is.
mounted on the outside of, and above, the parent cannon. Depending upon
the design and caliber of the gun, it mayor may' not have its own recall
mechanism.                                                                  ~

         b. Subcallber tube. (Fig. 83.) - A subcaUber tube is a tube which
is mounted in the bore of the cannon with which it is used. The tube has
neither a recoil system nor a breech mechanism of its own but bears .
directly against the breechblock of the larger cannon, thereby transmitting
the recoil forces to the parent cannon. The subcaUber tube is loaded
with fixed ammunition and is closed and fired by the breech mechanism
and firing mechanism of the larger cannon.                                .

                                                        OS 9-48

     FIGURE    82. - ,;UBCALIBER           GUN.

     BREECHBLOCK 0'-   PARENT   eN     •

                        _ SUBCA      IOCR TuBE"

      FIGURE   8, . - sUBCALIBER            TUBE.

                        -77 -
OS 9-48
                               ORDNANCE SCHOOL

                                    APPENDIX II

                             LIST OF REFERENCES
          1. Technical   Manuals.    _

                 Coast Artillery Weapons and Materiel           .....       TM 4-210
                 Ordnance Materiel - General  •..........                  TM 9-2005
                 155 mm Gun Materiel, M1 .. ','                             TM 9-350

      2. Field Artillery      School Publications.        _

                 Materiel (Elementary), 1937 .•...••.....                   FAB 100
                 Construction of Field Artnlery Materiel,         1941. .     Mat-3
      3. Ordnance Department             Documents.   _
                 Handbook of Artillery, revised May, 1924                               ,I
                   Washington Government Printing Office'J
                   1925 ••.••......................                         No.' 2033
                 Railway Artillery Characteristics       and Scope of                        I
                   Utility, Volume I, Washington Government
                   Printing Office. • . . • • . • . . . . . • • . . . ..    No. 2034         I
                 American Coast Arlillery Materiel, June 1922
                   Washington Government Printing Office,                                    I
                   1923 .••••.•.•.••.•........•...                          No. 2042
      4. Miscellaneous       Publications.      _
                Elements of Ordnance, Lt. Col. Thomas J. Hayes,
                  John Wiley and Sons, Inc., 1938                                            I
                Ordnance and Gunnery, Lt. Col. Ormond M. Lissak,
                  John Wiley and Sons, Inc., 1915
                Modern Military Dictionary, Col. Max B. Garber,
                  Max B. Garber, 1936                                                        I

                                                                                                  OS 9-48
                     FUNDAMENTALS                OF ARTILLERY                    WEAPONS


                                                                                Paragraphs         Pages

Artillery:                                                                                   4          5
     Definition and classification                                     .                                6
  . Weapon, components of                                              .
AXles:                                              .                             I!:     56           61
     Definition                                        .               .                               61
      For axle traverse                                                .                               62
      For pintle traverse             ..............•                                                  62
    .For sprung carriage                 .....•........                                                29
Barbette carriage                                                       .                 60           63
Bogies                                   , ........•..•.                                               48
Bottom carriage                                                            .
Breech:                                                       .
      Mechanisms:                                                                          13 .        11
          Definition                                                    .                  14          11
          Firing mechanisms                                             .                              27
          Obturator                                                     .                           18-20
          Operating mechanism                     .....•.•...                                          27
          Safety devices            ....••..........                                       19          16
          Semiautomatic             .............••.                                                   11
          Types ................•...•.                                                     10              9
      Ring ..........•..•.....•                                 ~. .   •.
Breechblock:                                                                                 17        14
       Eccentric-screw            ...............••                                          15        12 .
       Interrupted-screw             •...•...........                                        18        15
       Sliding-wedge                                                        .                16        13
      Welin ............•......•....                                                         38     42-44
 BUffer, counterrecoil               ........•.......                                         9         8
 Built-up cannon .................•.•                                                   app. I         76
 CaUber, definitiun of •.....••.........
 Cannon:                                                                                    9              8
       Construction          ........•...•......                                                           7
       Tube     ....•.......•.•...•.•.••                                                                   6
       Types                                                                .
                                                                                            5                  '-
 Carriage:                                                                                   48         48
        Bottom ........•....•.........                                                       33         29
       Definition       ....•............••..                                                           48
        Top ..............•.......•••                                                                   29
        Types                                                               .                           47
 Cradle .....................••....
 Counterrecoil:                                                                            38           '42
        Buffer •.•.•.........•.........                                                                 39
        Mechanisms ..•.•.•                   '.••.•..•.....                                             42
 Dashpot buffer ............••.•.•..•                                                                   50
 Dependent line of sighting ........•...•••

 OS 9-48                                                                                                  .\

                                      ORDNANCE SCHOOL
                                         , INDEX (CON'T)

                                                                            Paragraphs        Pages
 Direct-contact        counterrecoU mechanism                           .
 Disappearing carriage                                                  .
                                                                                     37          .40           I
 Drop-block breechblock                                                 .                18
 Eccentric-screw           breechblock                                  .                17
 Elevating mechanisms:                                                                            141
       Construction                                                 .                51
       Definition .•.....................                                            49
       Types ..•..............•......
 Equalizers:                                                                         50           50           I
      Definition ..••...•.•............                                              64
       Types ...................•....                                                65          ~~
      Action of ..............•.......                                               40          45
      Definition         .••............•.....                                       39          45
       Pneumatic •....................                                               42
                                                                                                 46            I
       Pneumatic-spring                .......•...•....                                  43      46
 Erosion ...........•...............
                                                                    .                41          46            I
                                                                             12, app. I       10,76
                •..•....•...............                                            20            18           I
      Jack •.....................•..                                                 67          72            I
      Lock      .••..•.......••.....•...                                             25
      Mechanisms:                                                                                21            I
          Continuous-pull                                           .
         Definition .•..•..........•....
                                                                                     25          21            I
                                                                                     24          21
          Electric         ..••.•..•...........                                      29          26
          Firing mechanism block                                    .                28          26

          Inertia ..••...........•......                                             26          23
          Percussion-hammer                       .•..........                                        1
                                                                                     27          26
      Segments . • . . . • • . . . . . . . . . . . . . •            .                68          72       -I
      Supports       ....•••...•...•.......                                          66
Floating-piston        counterrecoil              mechanism         .                37          ~i j
GraVity counterrecoil
                                    mechanism               .. .    .                37
                                                                                                 39 I
      Definition        .......•.............                                      4, 5        5,6
      Subcaliber        ...................•.                                          5          5
Horizontal sliding-wedge breechblock •....•                                          18          15
Howitzer ..••.•...•••.•...........                                                 4,5         5, 6
Hydraulic brake •.•.•••.....•.•.....                                                 36          33
Hydropneumatic counterrecoil                       mechanism ...                     37          40
Hydrospring recoil system ......•......                                              37          40
Independent line of sighting •.•..........                                           50          51
Interrupted-screw           breechblock                ...•.•....                    15          12
                                                                                                   OS 9-48

                                              INDEX (CON'T)
                                                                            Paragraphs              Pages

                                                                                          67            72
Jack, firing                                                           .                  50         50-54
Line of sighting ......•...........•.                                                     12            10
Ll.ner" removable .......•.                       ;                    .          I!:      4              5
MobUeartillery          ..•...•...•...•.....                                               9              9
Monobloc cannon                                                         .                4,5           5,6
Mortar .....•....................                                                       app. I          77
 Muzzle velocity, definition of                                         .                  17            14
 Nordenfeld breechblock                                                  .                 31            27
 Obturation, definition ..•..........•...                                                  32            27
 Obturator, De Bange                                         '           .
 Operating mechanism, breechblock:                                                          22          18
      Carrier-supported               .....••.....•.•                                       21          18
      Definition                           '                              .                 23          20
      Tray-supported                                                        '               62          67
 Outriggers                                                               .             app. I          76
 Primer, definition of ...•......••...•.                                                    49          50
 Quadrant elevation, elements of ...•••..••
 Railway:                                                                                    4            5
       Artillery .•.•......•...........                                                     34           31
       Mounts .........•.....•...•.•.                                                       36           38
  Recoil, variable length of                                               .
  Recoil systems:                                                                           38           42
       Buffer .......•................                                                      37           39
       Counterrecoll mechanisms                                      .                      35           33
       Definition        .....•...•...•.......                                              36           33
       Recoil brake .....•.••...........                                                    37           40
       Hydropneumatic ..........•......                                                     37           40
        Hydrospring ..•...•..•..........                                                    12            10
  Removable liner ...............•....                                                       11            9
  Rifling'. . ..•....•..•....•......•..                                                      38           44
   Respirator ...........•..•.........                                                       30           27 "'--
   Safety devices, breech mechanism                            ..•..•.                       38           44
   Schindler buffer .•..•.••.••••.•..•••                                                     50           53
   Semi-independent line of sighting ...•.....                                               45           47
   Sleigh .. . '. . . . • . . . • . . . . . .'. . . . . . . . .                              18            15
   Sliding-wedge breechblock                   .....•..•....                                 63           70
   Spades . . . . . . . . . . . . . . . . . . . • • . • • . . •                               16           13
   Stepped-thread breechblock                                                 .                5            5
   Subcaliber guns and tubes ....•........•                                                   36       34-33
   Throttling devices ...•.....•.......•.                                                     47           48
    Top carriage        .......•..•..•....•...                                                61           65
    Trails ......•........•..•........

 OS 9-48
                                 ORDNANCE       SCHOOL

                                       INDEX (CON'T)

                                                         Paragraphs        PageS
Traversing mechanisms:
    Definition ..••......•..........
     Types:                                                           52      56,
         Axle •••••••.•.•..••••.•••.•                                         56 "
         Base ring and racer .........•...
                                                                  55          58 .
         Pintle ......•..•.•..........                            54
Tube:                                                                        .58       ,I
     Components of ....••......•.....
     Definition  •..•••.••••...•......
                                                                              f~        I
     Subcaliber  ......•.•..•.........
Variable length of recoll           ..••..••.•..•.
WeHn breechblock . • • • • . • • . • . . . . • . . . •
                                                                  36          3~        I
                                                                  16          13        I






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