JLG 723A Service Manual - Manual (Page 101)

8-19 L2906H, 2906H, 3507H, 619A, 723A, 29.6LP, 29.6, 35.7
Hydraulic System
2. Connect the hydraulic hoses, fittings, solenoid wire
terminal leads, etc., to the steer select valve and
manifold.
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 tube and hose clamps.
4. 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.
5. Inspect for leaks and check the level of the hydraulic
oil in the reservoir. Shut the engine OFF.
Note: Check for leaks and repair as required before
continuing. Add hydraulic oil to the reservoir as needed.
6. Wipe up any hydraulic oil spillage in, on, near and
around the machine, work area and tools.
7. Close and secure the engine cover.
8. Remove the Do Not Operate Tags from both the
ignition key switch 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
8.6.6, “Steering Pressure Checking,” Section 8.7,
“Hydraulic Schematic,” or Section 9.9, “Electrical
System Schematics.”
8.11.7 Inching Valve
The inching valve is attached at the front of the frame
directly above the steer select valve.
Verify the correct operation of the inching valve before
considering replacement of the valve. The housing of the
inching valve is not serviceable and must be replaced if
defective.
a. Inching Valve Removal
1. Park the machine on a firm, level surface, fully
retract the boom, lower 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 engine cover. Allow the system fluids to
cool.
4. Label or otherwise mark the hydraulic hoses in
relation to the inching valve. Disconnect and cap all
hoses, fittings, etc.
5. Remove the capscrews that attach the valve to the
frame.
6. Remove the inching valve from the machine. Wipe
up any hydraulic oil spillage in, on, near and around
the machine.
b. Inching Valve Disassembly, Cleaning, Inspection
and Assembly
1. Place the inching valve assembly on a suitable work
surface.
2. Remove the cartridge (1) from the inching valve
housing.
3. Clean all components with a suitable cleaner before
inspection.
4. Inspect the 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 inching 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 oil 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.
MZ5550
1