TM 9--2520--215--34
0005 00--5
THEORY OF OPERATION -- CONTINUED
0005 00
HYDRAULIC SYSTEM – Continued
Action Of Hydraulic System In Low Range, Converter Drive, No Steer
NOTE
Refer to Torque path in low range, converter drive, no steer schematic view for the torque
path through the transmission.
When in low range, converter drive, no steer, the hydraulic system functions as described above except that
the following additional circuits are opened (or closed) to the action of the oil flow and pressure:
The range--selector valve directs oil to the low--range clutch
The output--driven brake coolant and pressure pump operates, since the vehicle is moving in a forward direc-
tion
With the range--selector valve in the low--range position, the line from the range--selector valve to the top of
the main pressure--regulator valve is exhausted.
Oil pressure from the range--selector valve applies the low–range clutch.
The output--driven brake coolant pump draws air when the brakes are released. It pumps the air through the
output reduction gear assemblies and then to the transmission gear compartment. The output--driven pressure pump
assists the input--driven pump in supplying oil to the system.
When the range selector valve is in the low--range position, the passage between the selector valve and the top of the
main pressure--regulator valve is open to the exhaust. With no pressure acting on the top of the main pressure--regu-
lator valve, the valve does move. This results in increased main pressure.
Governor pressure, if output speed is great enough, will raise the shift inhibitor valve. This will push the shift inhibitor
into the path of the lugs on the range selector inner lever. Refer to Equipment Data Downshift Inhibitor limits. In this
position, the inhibitor prevents the range from being shifted manually to reverse range. However, upshifts to inter-
mediate or high range, or a shift to neutral, can be made.
Governor pressure will actuate the lockup relay valve. However, since no pressure is available to lockup in low range,
the lockup relay valve has no function.
LOW---RANGE CLUTCH APPLIED
DIRECTION OF TRAVEL
Torque Path in Low---Range, Converter Drive, No Steer---Schematic View
