The lockup cutoff valve is positioned in the bore by spring pressure.
(4) Reverse operation - Brakes Applied (ON)(fig. A-11).
The
brake apply lever moves the brake apply regulator against its spring
through a mechanical linkage from the service brake pedal. Movement
of the valve directs main pressure to the brake apply circuit and the
brake signal circuit.
Brake signal pressure moves the primary brake coolant valve, allowing
cooler-out oil to the brake coolant circuit. Lubrication then feeds
through an orifice.
The reverse signal pressure moves the reverse signal brake valve
against its bore, blocking brake signal pressure.
Spring force and cooler-out oil position the secondary brake valve in
its bore, and with brake signal pressure blocked at the reverse
signal brake valve, it remains in this position.
This prevents
cooler-out oil from entering the output pump circuit.
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.
Brake apply pressure is directed to the brake pistons (to apply the
brakes), priority valve, and lockup cutoff valve.
The brake apply
pressure moves the priority valve, giving priority to control and
brake functions.
Brake apply pressure moves the lockup cutoff valve against its
spring, cutting off lockup clutch feed.
The transmission is now in
the converter phase.
Reverse signal pressure moves the main boost valve plug up in its
bore, providing a main pressure schedule of 300 psi.
The concludes the portion of the lesson on the X1100-3B transmission
hydraulic system.
This lesson continues with a description of the
steer system and final drives used with this transmission.
57
OD1710
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