TM 5-3805-258-24-1
POWER TRAIN
TRANSMISSION HYDRAULIC CONTROLS
Neutralizer Valve
When the left brake pedal is pushed, air pressure,
from the brake system, moves neutralizer valve (12)
against the force of its spring. The movement of valve
(12) opens the chamber at the left end of pressure
differential valve (14) to the reservoir through the
neutralizer valve body. The force of the springs and
the oil pressure in the spring chamber of the pressure
differential valve, move the valve to the left. The
movement of valve (14) opens the direction clutch
circuit to the reservoir through the right end of the
valve. The valve spool moves further to the left, until
the flow of pump oil to the direction clutch is stopped.
At this time, pressure differential valve (14) is in a
position to let the pressure increase in the direction
clutch circuit, when the left brake pedal is released.
Ratio Valve for Converter Inlet
The ratio valve (16) for the torque converter,
controls the maximum pressure to the converter. Its
S Y S T E M S O P E R A T I O N
primary purpose is to prevent damage to the converter
components when the engine is started with cold oil.
The pressure to the torque converter, caused by
restrictions to flow, is felt against the left end of valve
spool (16). This pressure pushes against the whole
diameter of the valve spool.
Pressure from the P1 clutch circuit is felt in the
slug chamber of the valve spool. This pressure pushes
against only the diameter of the slug.
The pressure (on the left end of valve) needed to
move the valve to the right is less than the pressure
(in slug chamber) needed to move the valve to the
left.
When the inlet pressure to the torque converter
gets to its maximum, the valve spool moves to the
right. This lets the extra oil go to the reservoir. When
the pressures are again in balance, the valve moves
back to the left.
All oil, not used by the clutches goes to the ratio
valve for the torque converter.
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