6.
The Control Valve Assemblies.
The control valve assemblies consist of the valves, springs, and
other components which control the selection of ranges and automatic
shifting of gears. The valve consists of a cylinder with a series of
ports and a cylindrical valve that can be shifted into various
positions by operation of the transmission controller located in the
driver compartment.
When the valve is shifted, various ports are
uncovered so that oil pressure is admitted, through the oil lines, to
the different clutches.
Oil pressure cannot be directed to more than one clutch at a time.
In neutral, oil pressure is cut off from the low-range clutch, high-
range clutch, and the reverse-range clutch so that there is no drive
to the output ring gears. However, steering in the neutral range can
be accomplished by various methods of operation of the steering
valves.
The control valve assemblies are mounted on the separator
plate and oil transfer plate assembly at the top of the transmission
center housing.
Figure 1-6 illustrates the relative mounting
position of the control valve in the transmission.
7.
The Braking System.
The braking system of the X200-4 transmission incorporates a service
brake and a parking brake system.
The service brake is a multiple
wet plate type which operates hydraulically with a mechanical
actuation. The mechanical action entails the operator depressing the
brake pedal.
The parking brake consists of a handle which operates in conjunction
with the service brake pedal. To set the parking brake, the operator
first depresses and then holds the service brake pedal in the
depressed position.
Once the service brake pedal is depressed and
held in position, the brake apply shafts are placed in the applied
position and the parking brake handle is raised. The raising of the
parking brake handle locks the service brake in the applied position
and prevents the vehicle from moving.
Remember that the parking brake handle only supplies enough force to
lock the service brake pedal.
It will not supply enough force to
actuate the service brake.
This completes part F.
You will now complete the Practice Exercise
to prepare you for the examination of this subcourse.
27
OD1714
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