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21 - 120
AUTOMATIC TRANSMISSION—30RH
DESCRIPTION AND OPERATION (Continued)
FRONT CLUTCH
DESCRIPTION
The front clutch assembly (Fig. 43) is composed of
the front clutch retainer, pressure plate, four clutch
plates, four driving discs, piston, piston return
spring, return spring retainer, and snap rings. The
front clutch is the forwardmost component in the
transmission geartrain and is directly behind the oil
pump and is considered a driving component.
NOTE: The number of discs and plates may vary
with each engine and vehicle combination.
OPERATION
To apply the clutch, pressure is applied between
the clutch retainer and piston. The fluid pressure is
provided by the oil pump, transferred through the
control valves and passageways, and enters the
clutch through the hub of the reaction shaft support.
1 – RETAINER HUB SEAL
2 – CLUTCH PISTON
3 – PISTON SPRING
4 – SPRING RETAINER SNAP RING
5 – CLUTCH DISCS
6 – PRESSURE PLATE
With pressure applied between the clutch retainer
and piston, the piston moves away from the clutch
retainer and compresses the clutch pack. This action
applies the clutch pack, allowing torque to flow
through the input shaft into the driving discs, and
into the clutch plates and pressure plate that are
lugged to the clutch retainer. The waved snap ring is
used to cushion the application of the clutch pack. In
some transmissions, the snap ring is selective and
used to adjust clutch pack clearance.
When pressure is released from the piston, the
spring returns the piston to its fully released position
and disengages the clutch. The release spring also
helps to cushion the application of the clutch assem-
bly. When the clutch is in the process of being
released by the release spring, fluid flows through a
vent and one–way ball–check–valve located in the
clutch retainer. The check–valve is needed to elimi-
nate the possibility of plate drag caused by centrifu-
gal force acting on the residual fluid trapped in the
clutch piston retainer.
Fig. 43 Front Clutch
7 – SNAP RING (WAVED)
8 – CLUTCH PLATES
9 – SPRING RETAINER
10 – PISTON SEAL
11 – FRONT CLUTCH RETAINER
XJ
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