JLG 4017RS Service Manual - Manual (Page 148)

Hydraulic System
8-18 3614RS, 4017RS
8.9.11 Steer Select Valve
The machine can be used in the front-wheel, four-wheel or
crab steering mode. The steer select valve (3) controls the
direction of hydraulic fluid flow to the steering cylinder
mounted on each axle. The steer select valve is attached
inside the frame between the can and the front axle.
Verify the correct operation of the steer select valve
solenoids before considering replacement of the valve. Refer
to Section 9.5, “Electrical System Schematics.” The housing of
the steer select valve is not serviceable and must be replaced
if defective.
a. Steer Select Manifold and Valve Removal
1. Park the machine on a firm, level surface, level the
machine, fully retract the boom, lower the boom, place
the transmission in (N) NEUTRAL, engage the park brake
and shut the engine OFF.
2. Place a Do Not Operate Tag on both the ignition key
switch and the steering wheel.
3. Open the engine cover. Allow the system fluids to cool.
4. Properly disconnect the battery.
5. Label, disconnect and cap the hydraulic hoses and the
electrical plugs connected to the steering select valve.
6. Remove the bolts holding the steer select valve to the
mounting plate on the frame.
7. Remove the steer select valve from the machine. Wipe
up any hydraulic fluid spillage in, on, near and around
the machine.
b. Steer Select Manifold and Valve Disassembly,
Cleaning, Inspection and Assembly
1. Place the steer select assembly on a suitable work
surface.
2. Separate the steer select solenoids from the spool.
Discard the o-rings.
3. Clean all components with a suitable cleaner before
inspection.
4. Inspect the solenoid cartridges for proper operation.
Check by shifting the spool to ensure that it is
functioning properly. Check that the spring is intact.
Inspect the cartridge interior for contamination.
5. Inspect internal passageways of the steer select valve
for wear, damage, etc. If inner surfaces of the manifold
DO NOT display an ultra-smooth, polished finish, or
components are damaged in any way, replace the
manifold or appropriate part. Often, dirty hydraulic fluid
causes failure of internal seals and damage to the
polished surfaces within the secondary function
manifold.
Note: ALWAYS replace seals, o-rings, gaskets, etc., with new
parts to help ensure proper sealing and operation. Lubricate
seals and o-rings with clean hydraulic oil.
6. Install the solenoids in the steer select housing.
c. Steer Select Valve and Manifold Installation
1. Install the steer select valve to the mounting plate
under the left front side of the frame using the two
bolts.
2. Connect all the hydraulic hoses, fittings, solenoid wire
terminal leads, etc., to the steer select valve
3. Check the routing of all hoses, wiring and tubing for
sharp bends or interference with any rotating members,
and install tie wraps and/or protective conduit as
required. Tighten all hose clamps.
4. Properly connect the battery.
5. Start the engine and run at approximately 1/3-1/2
throttle for about one minute without moving the
machine or operating any hydraulic functions.
6. Inspect for leaks and check the level of the hydraulic
fluid in the reservoir. Shut the engine OFF.
Note: Check for leaks and repair as required before continuing.
Add hydraulic fluid to the reservoir as needed.
7. Wipe up any hydraulic fluid spillage in, on, near and
around the machine, work area and tools.
8. Close and secure the engine cover.
MZ8080
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