THEORY OF OPERATION - CONTINUED
TRANSMISSION - CONTINUED
Pump oil flows into port from pump. Pump oil flows into orifice and unseats ball. When ball unseats, spring com-
presses against slug. Pump oil flows past ball and into chamber. Pressure in chamber moves spool to right against
spring. When spool moves to right, pump oil in port from pump flows past spool and into port to torque converter
as torque converter oil. Oil in chamber is vented to port to tank as tank oil.
Pressure in port from pump will vary slightly with demand from clutches. When pressure changes, spool will move
in order to maintain required engagement pressure to clutches. Spool will direct unneeded flow to port to torque
When pressure in port decreases, spring will move spool to left. When spool moves to left, oil flow into port to
torque converter will be blocked. As pressure drops further, spring will push ball to right. When ball moves to
right, oil flow from port from pump into chamber will be blocked. Oil in chamber will drain back into port from
pump through orifice when ball is moved to right.
There are six clutches used to transfer power from input shaft assembly to output shaft assembly.
There are three direction clutches.
(a) Clutch 1 (forward low)
(b) Clutch 2 (forward high)
(c) Clutch 3 (Reverse)
There are three speed clutches.
(a) Clutch 4 (second speed)
(b) Clutch 5 (third speed and fourth speed)
(c) Clutch 6 (first speed)
In order for power to be transferred through transmission to output shaft assembly, one direction clutch and one
gear clutch must be engaged. Each clutch is controlled by a modulating valve. Machine ECM controls proper
clutch engagement by sending a variable signal to modulating valve solenoids.
Clutch 2 and clutch 1 are co-located on one shaft assembly. Clutch 3 and clutch 4 are co-located on one shaft
assembly. Clutch 6 and clutch 5 are co-located on one shaft assembly.
When transmission is in NEUTRAL, clutch 5 is engaged.