JLG 723A Service Manual - Manual (Page 102)

Hydraulic System
8-20 L2906H, 2906H, 3507H, 619A, 723A, 29.6LP, 29.6, 35.7
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. 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. 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 drive
pump and engage the service brakes.
2. If further troubleshooting is required, refer to Section
8.7, “Hydraulic Schematic.”
8.11.8 Anti-Kick Valve
The anti-kick valve is attached at the left rear of the frame
directly in front of the main control valve.
Verify the correct operation of the anti-kick valve before
considering replacement of the valve. The anti-kick valve
must be replaced if defective.
a. Anti-Kick 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 anti-kick valve. Disconnect and cap all
hoses, fittings, etc.
5. Remove the capscrews that attach the valve to the
frame.
MZ5550
2