TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
TRANSMISSION - CONTINUED
21.
Fourth Speed Forward.
a.
Machine ECM determines proper clutches to engage based on inputs to machine speed, engine speed, and operator
inputs.
b.
Machine ECM modulates electrical current sent to selected clutch solenoids. Clutch solenoids are located on mod-
ulating relief valves.
c.
Modulating current to clutch solenoid controls clutch pressure by shifting spool in modulating valve.
d.
When transmission direction and shift lever is moved to FOURTH SPEED FORWARD, modulating valve solenoid
on for clutch 5 (third speed and fourth speed) is energized and modulating valve solenoid for clutch 2 (forward
high) is energized. When modulating valve solenoid for clutch 2 is energized, modulating valve directs pump oil to
clutch 2 to engage clutch. When modulating valve solenoid for clutch 5 is energized, modulating valve directs
pump oil to clutch 5 to engage clutch.
e.
Oil in clutches that are not engaged is sent back to sump as return oil.
f.
Transmission relief valve controls pump oil pressure supplied to modulating valves. Transmission relief valve
directs unneeded pump oil to torque converter as torque converter oil. Torque converter outlet oil flows through
torque converter outlet relief valve to oil cooler as lubrication oil. After oil cools, it flows to transmission for trans-
mission lubrication. After transmission is lubricated and cooled, oil drains to sump.
g.
Torque converter inlet relief valve limits torque converter inlet oil pressure to protect torque converter.
0003 00-76
