SkyTrak 8042 Service Manual - Manual (Page 515)

Hydraulic System
8.100 Model 8042, 10042, 10054 Legacy Rev. 10/03
8.12.6 Steer Select Valve
The vehicle can be used in the front-wheel, four-wheel or
crab steering mode. The steer select valve (1) controls
the direction of hydraulic fluid flow to the steering
cylinders mounted on each axle. The steer select valve
(1) is attached to a manifold mounted on a mounting plate
inside the frame near the fuel tank.
The steer select valve (2) contains two solenoids (3) that
direct the flow of hydraulic fluid according to steering
input. The valve is a direct, dual solenoid operated, spool-
type main control valve.
The valve consists of a housing (7), two solenoids (3), a
control spool (4) and two return springs (5). In the de-
energized state, the spool (4) is held by the return springs
(5) in the center position.
The spool is shifted via the action of the two wet-pin type
solenoids (3). The force of an acting solenoid pushes
against the push pin (6) on the end of the spool (4). The
spool is shifted from its normal position to the end position
for selected flow.
When the solenoid is de-energized, the control spool (4)
is returned to its normal condition by the centering
springs (5).
Verify the correct operation of the steer select valve
solenoids before considering replacement of the valve.
Refer to Section 9.7, “Electrical System
Troubleshooting,” and Section 9.14.9, “Steer Select
Switches.” The housing (7) of the steer select valve is not
serviceable and must be replaced if defective.
a. Steer Select Manifold and Valve Removal
1. Park the vehicle on a firm, level surface, fully retract
the boom, raise the boom, place the travel select
lever in (N) NEUTRAL, place the neutral lock lever in
the (N) NEUTRAL LOCK position, engage the park
brake switch and shut the engine OFF.
2. Place an Accident Prevention Tag on both the
ignition key switch and the steering wheel, stating
that the vehicle should not be operated. Refer to
Section 1.5, “Accident Prevention Tags.”
3. Temporarily block up or support the raised boom.
MH3750
Front
1
WARNING:
DO NOT get under a raised
boom unless the boom is blocked up. Always
block the boom before doing any servicing that
requires the boom to be up. Unexpected lowering
of the boom may cause death or serious injury.
MA8370
2
3
4
5
6
7
3
5
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