TM 5-3805-291-23-1
THEORY OF OPERATION - CONTINUED
0003 00
POWERTRAIN - CONTINUED
a.
General.
(1)
Transmission hydraulic system consists of these components: suction screen and magnet, transmission oil
pump, transmission oil filter, transmission hydraulic control relief valve, transmission clutch modulating
valves for clutches 1 thru 6, torque converter, torque converter inlet relief valve, torque converter outlet
relief valve, and oil cooler.
(2)
Bottom of output transfer gear case contains oil sump. Transmission oil pump is a one-section gear type
positive displacement pump which supplies oil to transmission hydraulic system. Transmission oil pump
pulls oil from oil sump. Oil flows through suction screen and magnet and is supplied to pump inlet through
a tube mounted to pump inlet and output transfer gear case. Pressurized oil exits pump outlet and flows to
externally mounted transmission oil filter. Pressurized oil flows from transmission oil filter through an
external hose to torque converter housing. Pressurized oil then flows through internal passages in torque
converter housing. Transmission hydraulic control relief valve receives some pressurized oil flow, as do
modulating valves for clutches 1 thru 6.
(3)
Modulating valves are mounted on top of transmission under cab. Six transmission clutches have an indi-
vidual modulating valve. To move machine, a direction clutch solenoid and a speed clutch solenoid must
be energized. Modulating valves are used to directly modulate oil pressure sent to each individual clutch.
Leakage oil and return oil from clutches flows to bottom of transmission. Nonenergized modulating valves
return oil flow to bottom of transmission, where it flows to oil sump in bottom of output transfer gear case.
(4)
Transmission hydraulic control relief valve controls pressure of oil flowing to clutch modulating valves.
Oil flows into transmission hydraulic control relief valve at a maximum pressure of 425 psi (2,930 kPa).
Oil pressure overcomes transmission hydraulic control relief valve spring force. Torque converter inlet oil
then flows to torque converter at 80 psi (552 kPa).
(5)
Torque converter inlet relief valve limits P3 torque converter inlet oil to a maximum pressure of 130 10
psi (900 70 kPa). Torque converter inlet relief valve is located in torque converter housing. Transmission
hydraulic control relief valve is located above torque converter inlet relief valve. Transmission hydraulic
control relief valve must be removed to access torque converter inlet relief valve.
(6)
Outlet oil from torque converter flows to torque converter outlet relief valve, which maintains oil pressure
inside torque converter at 60 20 psi (415 140 kPa). Oil flows from torque converter outlet relief valve
to oil cooler.
(7)
Oil cooler is located on right-hand side of engine. After oil has been cooled, oil flows to transmission, pro-
viding lubrication and cooling. Oil flows through internal passages in transmission bearings, gears, and
clutches, then to bottom of transmission where it flows to oil sump in bottom of output transfer gear case.
0003 00-41
