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gear box of a car

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					            GEAR BOX




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FUNCTIONS
 To provide variation in speed and torque as
  per the requirement and thereby providing
  mechanical advantage.
 To provide neutral condition for the vehicle
  to disengage the transmission from gear to
  remaining parts of transmission.
 To provide reverse movement of vehicle
  without changing the direction of rotation of
  crankshaft.

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TRANSMISSION NECESSITY




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CLASSIFICATION
            Manual operated
            Semi-automatic
            Fully-automatic transmission
                                     GEAR BOX


                   PROGRESSIVE      SELECTIVE     PRE SELECTIVE



                                                         EPICYCLIC


                SLIDING MESH      CONSTANT MESH    SYNCHROMESH




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PROGRESSIVE & SELECTIVE




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PRESELECTIVE




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SLIDING GEAR BOX




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CONSTANT MESH GEAR BOX




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Double Declutching
       In the constant mesh box, for the smooth engagement the
        speed of mainshaft gear and the sliding dog must be equal.
       To obtain lower gear, the speed of the clutch shaft, layshaft
        and main shaft gear must be increased. This is done by
        double declutching.
       The clutch is disengaged and the gear is brought to neutral.
        Then the clutch is engaged and accelerator pedal pressed to
        increase the speed of the main shaft gears. After this the
        clutch is again disengaged and the gear moved to the required
        lower gear and the clutch is again engaged. As the clutch is
        disengaged twice in this process, it is called double
        declutching.
       For changing to higher gear, however, reverse effect is desired
        i.e., the driver has to wait with the gear in neutral till the main
        shaft speed is decreased sufficiently for a smooth engagement
        of the gear.

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ADVANTAGES OF
CONSTANT MESH GEAR BOX
       Helical or double helical gear teeth can be used -
        quieter.
       Synchronizing devices - smooth engagement.
       Any damage to the dog clutch teeth and not to the
        teeth of the gear wheels.
       Once the dog clutches are engaged, there is no
        motion between their teeth.
       If the teeth on the wheel are damaged, the motion
        will be imperfect and noise will result.
       Damage is less likely to occur to the teeth of the
        dog clutches, since all the teeth engage at once,
        whereas in sliding a pair of gears into mesh the
        engagement is between two or three teeth.

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SYNCHROMESH GEAR BOX




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TRANSFER BOX




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LUBRICATION OF GEAR-BOX
 Dip and splash system
 Correct Grade of oil
 Correct quantity of oil
 Regular intervals
 Ventilation




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MECHANICAL GEAR LEVER ON
TOP OF TRANSMISSION CASE




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MECHANICAL GEAR LEVER ON
TOP OF TRANSMISSION CASE




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SELECTOR MECHANISM WITH GEAR
LEVER ON THE STEERING COLUMN




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REMOTE CONTROL LINKAGE
FOR GEAR SELECTION




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            Any Questions?




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