JLG G5-18A Service Manual - Manual (Page 110)

Hydraulic System
8-20 G5-18A, 2505H, 25.5
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
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.
6. Install the cartridge in the inching valve housing.
c. Inching Valve Installation
1. Attach the inching valve to the mounting plate on the
frame using the socket head capscrews.
2. Connect the hydraulic hoses, fittings, etc., to the
inching valve.
3. Check the routing of all hoses and wiring 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 battery and engine covers.
9. Remove the Do Not Operate Tags from both the
ignition key and the steering wheel.
d. Inching Valve Bleeding Procedure
Carefully bleed the inching valve as soon as the inching
valve is installed on the machine. Air in the system will not
allow the brakes to apply properly. There is one bleeder
location on the inching valve. Work with an assistant to
perform this procedure.
1. Place the transmission control lever in
(N) NEUTRAL, engage the park brake, start the
engine and lower the boom. Turn off engine.
2. Remove the plastic cap (2) from the inching brake
bleeder. Attach one end of a length of transparent
tubing over the bleeder. Place the other end of this
tubing in a suitable transparent container that is
partially filled with hydraulic oil. The end of the tubing
must be below the oil level in the container.
3. DO NOT open the bleeder without holding the tubing
firmly on the bleeder. Have an assistant depress the
brake pedal. Carefully open the bleeder with a 10
mm wrench. Close the bleeder when air bubbles no
longer appear in the oil. Release the brake pedal.
Remove the tubing from the bleeder.
4. If brake system bleeding is required, refer to Section
8.11.2, “Service Brake Valve.”
5. Check brake fluid level and add fluid if necessary.
Refer to Section 2.4, “Fluids, Lubricants and
Capacities.”
e. Inching Test
1. Start the machine, engage the shift lever to the
forward position and release the parking brake.
Slowly depress the throttle to 1/2 throttle. Slowly
apply the service brake. The machine will slow, but
still maintain forward movement. Continuing to
depress the service brake will disengage the inching
brake and engage the service brakes.
2. If further troubleshooting is required, refer to Section
8.7, “Hydraulic Schematic.”
MY2330
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