TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
TRANSMISSION - CONTINUED
19.
Second Speed Forward.
a.
Machine ECM determines proper clutches to be engaged based on inputs such as 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 SECOND SPEED FORWARD, both modulating valve
solenoid for clutch 4 (second speed) and modulating valve solenoid for clutch 1 (forward low) are energized.
When modulating valve solenoid for clutch 1 is energized, modulating valve directs pump oil to clutch 1 to engage
clutch. When modulating valve solenoid for clutch 4 is energized, modulating valve directs pump oil to clutch 4 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 in order to protect torque converter.
0003 00-68