JLG G5-18A Service Manual - Manual (Page 113)

8-23 G5-18A, 2505H, 25.5
Hydraulic System
8. Close and secure the battery and engine covers.
9. Remove the Do Not Operate Tags from both the
ignition key and the steering wheel.
d. Steering Test
1. Start the machine and select either the 4-wheel
steer or the crab steer mode.
2. Turn the steering wheel until the left rear wheel is
aligned with the side of the frame.
3. Select the 2-wheel steer mode and turn the steering
wheel until the left front wheel is aligned with the
frame.
4. With the wheel now aligned, select the desired steer
mode.
5. If further troubleshooting is required, refer to Section
8.6.5, “Steering Pressure Checking,” Section 8.7,
“Hydraulic Schematic,” or Section 9.4, “Electrical
System Schematics.”
8.11.10 Quick Attach Valve
The quick attach valve is located on the left side of the
boom head.
Verify the correct operation of the quick attach valve
solenoid before considering replacement of the valve.
The housing of the quick attach valve is not serviceable
and must be replaced if defective.
a. Quick Attach Valve Removal
1. Park the machine on a firm, level surface, fully
retract the boom, raise the boom, place the
transmission control lever 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, stating that the
machine should not be operated.
3. Open the battery and engine covers. Allow the
system fluids to cool.
4. Properly disconnect the battery.
5. Label or otherwise mark the hydraulic hoses in
relation to the quick attach valve (1). Disconnect and
cap all hoses, fittings, solenoid wire terminal leads,
etc.
6. Remove the quick attach valve from the machine.
Wipe up any hydraulic fluid spillage in, on, near and
around the machine.
b. Quick Attach Valve Disassembly, Cleaning,
Inspection and Assembly
1. Place the quick attach valve assembly on a suitable
work surface.
2. Remove the solenoid valve and cartridge (2) from
the quick attach valve housing.
3. Clean all components with a suitable cleaner before
inspection.
4. Inspect the solenoid cartridge 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 decompression
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 unit.
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.
MY8670
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