Absence of converter-in oil allows spring force to move the output
pump bypass valve which stops the bypass function.
Brake apply pressure is directed to the two brake apply
pistons (to
apply the brakes), priority valve, main boost valve,
and lockup
cutoff valve. Brake apply pressure moves the boost plug
causing the
main pressure regulator valve to move up increasing main
pressure up
to 300 psi.
The brake apply pressure moves the priority valve giving priority to
control and brake functions.
Brake apply pressure also moves the
lockup cutoff valve against its spring cutting off lockup clutch
feed. The transmission is now in converter phase.
(3) Reverse operation - Brakes Released (OFF)(fig. A-10).
Spring force holds the brake apply regulator in the "off" position,
blocking main pressure from entering the brake apply circuit and
brake signal circuit.
The primary brake coolant valve, positioned in its bore by spring
force, allows cooler-out oil to pass through the valve to provide
lubrication.
The reverse signal valve is positioned in its bore by the calibrated
spring.
Spring pressure and cooler-out oil position the secondary brake valve
in its bore and prevent cooler-out oil from entering the output pump
circuit.
The output pump signal valve, positioned in its bore by spring force,
directs converter-in oil pressure to the output pump bypass valve.
Converter-in pressure moves the output pump bypass valve against its
spring. Because of the rotation of the output pump gears there is no
"bypass" of oil.
When the vehicle travels in reverse, it causes the output pump gears
to rotate in a reverse direction.
This, in effect, reverses the
suction side and pressure side of the pump.
The output pump now
attempts to draw oil from the hydraulic system instead of the
reservoir.
To prevent this, the output pump check valve and the
brake cooling valve close.
Main pressure directed to the top of the priority valve holds this
valve down and provides full-flow clutch feed.
Reverse signal pressure moves the main boost plug up in the bore
providing a main pressure schedule of 300 psi.
56
OD1710
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