ZF Automatic Transmissions Service Manual
The torque converter acts in all four forward gears and in reverse. The converter lock-up clutch closes in 4th gear at
a point depending on road speed and accelerator position; engine power is then transmitted
by purely mechanical
means.
A low
-loss oil pump in the front of the transmission housing supplies the converter, the automatic gear shift and the
lubrication circuit; oil is drawn from a sump in the bottom of the gear train housing through a filter. The pump drive
gear is keyed to the converter impeller hub and therefore turns when the engine is running, thereby pressurizing the
oil.
2.1.2 Four-speed Epicyclic Gear Train
The torque converter drives a mechanical epicyclic gear train providing four forward ratios and reverse. Individual ra-
tios are obtained by coupling together the various parts of the gear train by means of solenoid-operated, hydraulically
actuated multi-disc clutches and brakes; built in freewheels permit gear shifts without any interruption of the power
flow.
For information on the operation of the solenoids, clutches, brakes and freewheels, refer to the table below and the
schematic diagrams shown overleaf.
A parking lock pawl is provided at the rear of the gear train, operating on a toothed wheel attached to the output shaft;
the parking lock is operated from the selector (position
'P) by actuator rod.
An electro
-magnetic sensor detects output shaft revolutions by means of a toothed disc attached to the shaft; one rev- olution of the shaft is equal to 36 pulses. The electrical signal from the sensor is passed, via a screened cable, to the
TCM.
R
Park,
Neutral
Solenoid ~
MV2
MVI, MV2
MVI, MV3
MV2
-
MV2
OWC
= one way clutch
Resulting clutch operation
A Clutch drives annulus clockwise
D Clutch OWC holds F carrier against shaft clockwise
E Clutch & OWC drives output shaft clockwise
A Clutch drives annulus clockwise
C1 Clutch holds sungear against anti-clockwise
C Clutch
& OWC holds sungear against anti-clockwise
A Clutch drives annulus clockwise
B Clutch drives sungear clockwise
C Clutch
& OWC holds sungear against anti-clockwise
A Clutch drives annulus clockwise
B Clutch drives sungear clockwise
C Clutch
& OWC holds sungear against anti-clockwise
B Clutch drives sungear clockwise
D Clutch holds carrier against clockwise
E Clutch & OWC drives output shaft anti-clockwise
E Clutch & OWC applied (hydraulics)
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Issue 1 August 1994
