TM-5-3805-254-14-P-2
TRUCK, DUMP, 20 TON, 6X4, ON-OFF HIGHWAY 71,000 GVW, IHC MODEL F-5070 (CCE)
TECHNICAL MANUAL; OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL SUPPORT AND DEPT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS INFORMATION AND SUPPLEMENTAL MAINTENANCE INSTRUCTIONS)
JUNE 1980
TM-5-3805-254-14-P-2 - Page 693 of 894
TRUCK SERVICE MANUAL
DESCRIPTION AND OPERATION
Para 2-23/2-26
(2)
The oil filter screens all oil entering the
hydraulic system.
2-25.
REAR COVER (A, foldout 16)
Rear cover 14 is made of cast iron and machined to
receive governor assembly 38 and first or low clutch
piston 4.
The rear cover provides support for output
shaft assemblies 19.
A parking brake mounting face
is also provided on the rear surface.
The cover is the
rear closure member and is attached to
the adapter
housing by twenty-four bolts 17 and 36.
2-26.
HYDRAULIC SYSTEM
a. System Functions.
The hydraulic system
generates, directs, and controls the pressure and flow of
the hydraulic fluid within the transmission.
The hydraulic
fluid (transmission oil) is the power transmitting medium
in the torque converter.
Its velocity drives the converter
turbine.
Its flow cools and lubricates the transmission
and its pressure applies the clutches.
b. System Schematics.
A Color-coded foldout
illustration of the hydraulic system IS presented at the
back of this manual (foldouts
5,
).
Each illustration
represents the system as it would function during neutral
operation and with the engine idling.
c. Oil Filter, Pump Circuit
(foldouts
5,
)
(1)
Oil (blue) is drawn from the sump
(transmission oil pan) through a fine-mesh filter screen
by the input-driven pump assembly.
(2)
The oil (red) is discharged by the input
pump through an external filter (when so equipped) and
into the bore of the main pressure regulator valve.
(3)
F or models equipped with a hydraulic
retarder, the oil is discharged from two sections of the
input pump.
The first section directs oil (red) to the
main-pressure regulator valve (item (2), above).
The
second section directs oil (black and green) to the
lubrication circuit, and assists in providing oil to the
converter-in circuit.
d. Main-Pressure Circuit
(foldouts
5,
)
(1)
Main pressure (red) is regulate by the
main-pressure regulator valve.
Oil from the pump flows
into the valve bore, through an internal passage in the
valve, to the upper end of the valve.
Pressure at the
upper end of the valve forces the valve downward
against the spring until oil (yellow) flows into the
converter-in circuit.
When flow from the pump exceeds
the circuit requirement, the converter bypass valve opens
and allows the excess to escape into the converter-out
circuit (orange).
(2)
Although main pressure is controlled
primarily by the spring force below the regulator valve, it
is also affected by the presence of forward regulator
pressure.
When this pressure is not present at the
regulator valve, main pressure is regulated at a higher
value.
(3)
Main pressure (red) is directed to several
points in the hydraulic circuit.
e. Converter, Cooler, Lubrication
Circuit (foldouts
5,
)
(1)
The converter circuit originates at the
main-pressure regulator valve.
Converter-in oil (yellow)
flows to the torque converter.
Oil must flow through the
converter continuously to keep it filled and to carry off the
heat generated within the converter.
(2)
Converter-out oil (orange) leaving the
torque converter, is directed to an external cooler
(supplied by vehicle or engine manufacturer).
When the
transmission includes a hydraulic retarder, converter-out
oil
flows
through
the
retarder
control
valve
686
TRANSMISSION
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