Chrysler Dodge Caravan 2002, Руководство пользователя

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STATOR
Torque multiplication is achieved by locking the
stator’s over-running clutch to its shaft (Fig. 236).
Under stall conditions (the turbine is stationary), the
oil leaving the turbine blades strikes the face of the
stator blades and tries to rotate them in a counter-
clockwise direction. When this happens the over–run-
ning clutch of the stator locks and holds the stator
from rotating. With the stator locked, the oil strikes
the stator blades and is redirected into a “helping”
direction before it enters the impeller. This circula-
tion of oil from impeller to turbine, turbine to stator,
and stator to impeller, can produce a maximum
torque multiplication of about 2.4:1. As the turbine
begins to match the speed of the impeller, the fluid
that was hitting the stator in such as way as to
cause it to lock–up is no longer doing so. In this con-
dition of operation, the stator begins to free wheel
and the converter acts as a fluid coupling.
TORQUE CONVERTER CLUTCH (TCC)
In a standard torque converter, the impeller and
turbine are rotating at about the same speed and the
stator is freewheeling, providing no torque multipli-
cation. By applying the turbine’s piston to the front
cover’s friction material, a total converter engage-
ment can be obtained. The result of this engagement
is a direct 1:1 mechanical link between the engine
and the transmission.
The engagement and disengagement of the TCC
are automatic and controlled by the Powertrain Con-
trol Module (PCM). The engagement cannot be acti-
vated in the lower gears because it eliminates the
torque multiplication effect of the torque converter
necessary for acceleration. Inputs that determine
clutch engagement are: coolant temperature, vehicle
speed and throttle position. The torque converter
clutch is engaged by the clutch solenoid on the valve
body. The clutch will engage at approximately 56
km/h (35 mph) with light throttle, after the shift to
third gear.
REMOVAL
(1) Remove transmission and torque converter
from vehicle. (Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - 31TH - REMOVAL)
(2) Place a suitable drain pan under the converter
housing end of the transmission.
CAUTION: Verify that transmission is secure on the
lifting device or work surface, the center of gravity
of the transmission will shift when the torque con-
verter is removed creating an unstable condition.
The torque converter is a heavy unit. Use caution
when separating the torque converter from the
transmission.
(3) Pull the torque converter forward until the cen-
ter hub clears the oil pump seal.
(4) Separate the torque converter from the trans-
mission.
INSTALLATION
Check converter hub and drive notches for sharp
edges, burrs, scratches, or nicks. Polish the hub and
notches with 320/400 grit paper or crocus cloth if nec-
essary. The hub must be smooth to avoid damaging
the pump seal at installation.
(1) Lubricate converter hub and oil pump seal lip
with transmission fluid.
(2) Place torque converter in position on transmis-
sion.
CAUTION: Do not damage oil pump seal or bushing
while inserting torque converter into the front of the
transmission.
(3) Align torque converter to oil pump seal open-
ing.
(4) Insert torque converter hub into oil pump.
(5) While pushing torque converter inward, rotate
converter until converter is fully seated in the oil
pump gears.
(6) Check converter seating with a scale and
straightedge (Fig. 237). Surface of converter lugs
should be 1/2 in. to rear of straightedge when con-
verter is fully seated.
(7) If necessary, temporarily secure converter with
C-clamp attached to the converter housing.
Fig. 236 Stator Operation
1 - DIRECTION STATOR WILL FREE WHEEL DUE TO OIL
PUSHING ON BACKSIDE OF VANES
2 - FRONT OF ENGINE
3 - INCREASED ANGLE AS OIL STRIKES VANES
4 - DIRECTION STATOR IS LOCKED UP DUE TO OIL PUSHING
AGAINST STATOR VANES
RS
31TH AUTOMATIC TRANSAXLE
21 - 127
TORQUE CONVERTER (Continued)