CCAS AUTOMOTIVE SKILL by nikeborome

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									    CCAS 3381
AUTOMOTIVE SKILL I
          OBJECTIVES
 To understand the operational
 principles and basic mechanisms
 of transmission system




          Lecture – 1 hour
         Workshop – 1 hour
     TRANSMISSION SYSTEM (1)



                                                 Manual
                              Manual
Manual transmission system                       gear box
                             gear knob




       Manual
       gear box                          5-speed manual gearbox
       TRANSMISSION SYSTEM (2)
   Green shaft (input shaft) & gear
    turn at the same rpm as the
    engine
   Red shaft (layshaft) & gears are
    directly connected to the input so
    it spins when input shaft spins
   Yellow shaft (output shaft) is
    splined shaft connected directly
    to drive shaft through differential
    to drive wheels (If wheels are
    spinning output shaft spins)
   If engine is off with car coasting
    output shaft turns inside blue
    gears (blue gears & layshaft are
    motionless)
   Collar connects one of two blue
    gears to output shaft via dog teeth
    TRANSMISSION SYSTEM (3)
   Moving knob forward & backward
    moves collar to engage the gears
   Reverse gear is handled by a
    small idler gear (purple)
   Importance of transmission:
     – Engine redline (max. rpm
       above which engine explodes)
     – Engines have narrow rpm
       ranges (horsepower & torque
       are at their maximum)
   Synchronizers allow collar & gear
    to make frictional contact before
    dog teeth make contact (collar &
    gear synchronize their speeds
    before teeth need to engage
TRANSMISSION SYSTEM (4)
                  A car engine spins all
                   the time & car wheels
                   don't (to stop without
                   killing the engine
                   wheels, engine needs
                   to be disconnected
Pressure plate
                   from the engine)
                  Flywheel connected to
                   engine
                  Clutch plate connected
                   to the transmission
 Clutch plate
    TRANSMISSION SYSTEM (5)
 Springs force on pressure plate
 Clutch plate springs - isolate
  transmission from shock of clutch
  engaging
 Friction material on the clutch disc wears
  out (similar to the friction material on the
  pads of a disc brake pads/shoes of a
  drum brake; clutch slips & lost of power)
 Driver who slips the clutch a lot will wear
  out clutch a lot faster
 Worn throw-out bearing (rumbling noise
  whenever the clutch engages)
    TRANSMISSION SYSTEM (6)
   Other clutches:
    – Automatic transmission with several
      clutches used to engage and disengage
      various sets of planetary gears
    – Car air conditioning compressor with
      magnetic clutch
    – Engine-driven cooling fan with
      thermostatically controlled viscous
      clutch
     TRANSMISSION SYSTEM (7)
   Ideally, transmission should be
    flexible in its ratios that engine runs
    at its single, best rpm value
    (continuously variable transmission -
    CVT) – Honda City
     TRANSMISSION SYSTEM (8)
   Manual transmission checklist:
    – Check for oil leaks (RM5000 new Kancil
      gearbox)
   Manual transmission test drive
    – With transmission lever in neutral,
      parking brake applied & engine idling,
      listen to any loud noises when clutch
      pedal pressed or released
    – Try to drive the car at all speeds one by
      one - every speed should shift smooth &
      easily without any noises or jerks
     TRANSMISSION SYSTEM (9)
   Manual transmission test drive
    – While driving at 2nd or 3rd gear, try to
      press down sharply on the accelerator
      pedal for an instance (clutch should
      not slip, any slipping i.e., engine rpm
      increases but speed remains the
      same clutch most likely has to be
      replaced)
    – Try to drive with acceleration &
      deceleration (there should be no
      whining or humming noise under any
      condition with all gears should shift
      easily & noiselessly)
    TRANSMISSION SYSTEM (10)
 Automatic transmissions:
   – no clutch pedal
   – no gear shift
 Automatic transmission (gearbox plus
  torque converter) – like manual
  gearbox & its clutch




 Torque      Auto       Auto transmission system
converter   gearbox
     TRANSMISSION SYSTEM (11)
 In automatic transmission, same set of
  gears produces all of the different gear
  ratios (planetary gearset)
 Planetary gearset
    – A set of bands to lock parts of gearset
    – Three wet-plate clutches to lock other parts
      of gearset
    – Hydraulic system controlling clutches &
      bands
    – Large gear pump to move transmission fluid
      around
   Planetary gearset has 3 main parts:
    – Sun gear
    – Planet gears & planet gears' carrier
    – Ring gear
TRANSMISSION SYSTEM (12)
    TRANSMISSION SYSTEM (13)
 Each of these 3 parts can be input,
  output or stationary (determines gear
  ratio)
 First Gear - 2.4:1
 Second Gear - 0.67:1
 3rd gear - 1:1 ratio in 3rd gear
 Overdrive has a faster output speed than
  input speed (output of engine goes
  straight to transmission)
 Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) =
  0.67:1 (an engine turning at 2000 rev/min
  output speed is 3000 RPM allowing cars
  to drive at freeway speed while the
  engine speed stays nice and slow
     TRANSMISSION SYSTEM (14)
   Differentials (where engine power, in most
    cars, makes its last stop before spinning
    the wheels)
     – Aim engine power at the wheels
     – Act as final gear reduction in the car
       (reduce rotational speed of transmission
       one final time before it hits the wheels)
     – Transmit power to the wheels while
       allowing them to rotate at different
       speeds during turning
   Device that splits engine torque two ways,
    allowing each output to spin at a different
    speed
   Differential is found on all modern cars &
    trucks, and also in many all-wheel-drive
    (full-time 4WD vehicles)
TRANSMISSION SYSTEM (15)




               Differential
    TRANSMISSION SYSTEM (16)
 Final drive ratio (gear ratio in the
  differential)
 Open differential always applies the
  same amount of torque to each wheel
 Two factors determining how much
  torque can be applied to the wheels:
   – equipment
   – traction
                    Dry conditions - torque
                     applied to wheels
                     limited by engine &
                     gearing
    TRANSMISSION SYSTEM (17)
 In low traction - amount of torque limited
  to greatest amount that will not cause a
  wheel to slip under those conditions (if
  you give the car more gas after the
  wheels start to slip, the wheels will just
  spin faster – problem with open
  differentials
 Limited slip differential (LSD) –
  positraction - allows more torque to be
  transferred to the non-slipping wheel
    TRANSMISSION SYSTEM (18)
   Automatic transmission checklist
    – Place your car at a level surface, start
      engine, set transmission lever to "P“
      & let engine idle
    – Pull transmission dipstick
    – Wipe it off with a lint free clean
      rag/tissue
    – Insert it back carefully all the way
      down into its place
    – Pull again & check fluid level
    TRANSMISSION SYSTEM (19)
   Automatic transmission
    checklist
     – Pull again & check fluid
       level
        Engine   cold fluid within
         "COLD" marks
        Engine hot fluid level at
         upper end of "HOT"
         mark (top it up if it is
         lower)
        Check fluid condition
         also: too black & a burnt
         smell -transmission may
         not last
    TRANSMISSION SYSTEM (20)
   Automatic transmission
    checklist
     – Pull again & check fluid
       level
        There should not be any
        metal filings or black
        flakes
   Topping up transmission
    fluid
     – Use only specified
       transmission fluid (check
       your manual)
     TRANSMISSION SYSTEM (21)
   Topping up transmission
    fluid
     – Add a small amount of
       fluid through dipstick
       pipe as shown in the
       image & do not overfill it
     – Wait for a few minutes
       to let fluid to flow down
     – Start engine & check
       level again
     TRANSMISSION SYSTEM (22)
   Transmission maintenance
    – Most of transmission troubles start
      after overheating
       Under  heavy load
       Continuous stop & go traffic in hot
        weather
       Racing
       Accelerating too hard to free the car
       At higher temperatures transmission fluid
        burns loosing its lubricating qualities &
        becomes oxidized leaving deposits all
        over inside
       Exposed to heat rubber seals & gaskets
        inside transmission become hardened
        causing leaks
     TRANSMISSION SYSTEM (23)
   Transmission maintenance
    – Most of transmission troubles start
      after overheating
       Metal   parts warp & loose their strength
    – Poor design
    – After being rebuilt by inexperienced
      technician
    – Harsh driving
    – Too low or too high transmission
      fluid level
    – Wrong transmission fluid type
     TRANSMISSION SYSTEM (24)
   How to prevent the transmission from
    damage
    – Always check your parking space for
      leaks (get it fixed before it caused
      something serious)
    – Once in a while check transmission
      fluid level & condition
    – Use only same type of the
      transmission fluid as specified in
      owner's manual
    – Never shift to “R” or “P” until car
      comes to a complete stop
     TRANSMISSION SYSTEM (24)
   How to prevent the transmission from
    damage
    – Never shift from “P” mode when
      engine rpm is higher than normal idle
    – Always hold a brake down when
      shifting from “P”
    – Do not tow with drive wheels on the
      road
    – Go to transmission shop when you
      experience any problems with your
      transmission such as leaks, noises,
      problems with shifting, etc.
    TRANSMISSION SYSTEM (25)
 ATF (owner’s manual)
 Fluid change (40,000 km or so)
 Good conditions – clean & odorless
 Transmission   screen/filter
   THE END
IQ + EQ + SQ = TQ*

								
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