Overrunning Clutch; Planetary Gearset - Jeep cherokee 2000 Service Manual

21 - 122 AUTOMATIC TRANSMISSION—30RH
DESCRIPTION AND OPERATION (Continued)
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.

OVERRUNNING CLUTCH

DESCRIPTION
The overrunning clutch (Fig. 45) consists of an
inner race, an outer race (or cam), rollers and
springs, and the spring retainer. The number of roll-
ers and springs depends on what transmission and
which overrunning clutch is being dealt with.
Fig. 45 Overrunning Clutch
1 – OUTER RACE (CAM)
2 – ROLLER
3 – SPRING
4 – SPRING RETAINER
5 – INNER RACE (HUB)
OPERATION
As the inner race is rotated in a clockwise direction
(as viewed from the front of the transmission), the
race causes the rollers to roll toward the springs,
causing them to compress against their retainer. The
compression of the springs increases the clearance
between the rollers and cam. This increased clear-
ance between the rollers and cam results in a free-
wheeling condition. When the inner race attempts to
rotate counterclockwise, the action causes the rollers
to roll in the same direction as the race, aided by the
pushing of the springs. As the rollers try to move in
the same direction as the inner race, they are
wedged between the inner and outer races due to the
design of the cam. In this condition, the clutch is
locked and acts as one unit.

PLANETARY GEARSET

DESCRIPTION
The planetary gearsets (Fig. 46) are designated as
the front and rear planetary gear assemblies and
located in such order. A simple planetary gearset con-
sists of three main members:
Fig. 46 Planetary Gearset
1 – ANNULUS GEAR
2 – SUN GEAR
3 – PLANET CARRIER
4 – PLANET PINIONS (4)
• The sun gear which is at the center of the system.
• The planet carrier with planet pinion gears
which are free to rotate on their own shafts and are
in mesh with the sun gear.
• The annulus gear, which rotates around and is
in mesh with the planet pinion gears.
NOTE: The number of pinion gears does not affect
the gear ratio, only the duty rating.
OPERATION
With any given planetary gearset, several condi-
tions must be met for power to be able to flow:
• One member must be held.
• Another member must be driven or used as an
input.
• The third member may be used as an output for
power flow.
• For direct drive to occur, two gear members in
the front planetary gearset must be driven.
NOTE: Gear ratios are dependent on the number of
teeth on the annulus and sun gears.
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