JLG G5-18A Service Manual - Manual (Page 90)

Hydraulic System
8.16 G5-18A/2505
Note: DO NOT disassemble the service brake valve.
The service brake valve is not serviceable and must be
replaced in its entirety, if defective.
b. Service Brake Valve Installation
1. Install the service brake valve to the steering column
support with the necessary hardware.
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.
2. Use new oiled o-rings as required. Uncap and
reconnect the previously labeled hydraulic hoses to
the appropriate locations.
3. Check the routing of all hoses, 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 one-third
to one-half throttle for about one minute, without
moving the machine or operating any hydraulic
functions.
5. Inspect the service brake valve and connections for
leaks, and check the brake fluid level. Shut the
engine OFF.
6. Replace the necessary dash panels.
7. Wipe up any hydraulic fluid spillage in, on, near and
around the machine, work area and tools.
8. Close and secure the engine covers.
Note: The service brake valve circuit will need to be
bled after installation. Refer to Section 8.10.4, “Brake
Test.”
8.10.3 Parking Brake Valve
The park brake valve is located in the cab, below the seat.
a. Park Brake 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 an 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 covers. Allow the system fluids to
cool.
4. Remove the four capscrews holding the cover below
the seat. The park brake valve is mounted on the
backside of the cover.
5. Label, disconnect and cap the hydraulic hoses on
each side and bottom of the park brake valve.
Disconnect and cap all hoses, fittings, etc.
6. Remove the two capscrews, and two lockwashers
mounting the park brake valve to the cover.
Note: DO NOT disassemble the park brake valve. The
park brake valve is not serviceable and must be replaced
in its entirety, if defective.
b. Park Brake Valve Installation
1. Install the park brake valve with the two lockwashers
and two capscrews to the cover.
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.
2. Use new oiled o-rings as required. Uncap, reattach
and secure the three hoses.
3. Check the routing of all hoses for sharp bends or
interference with any rotating members, and install
tie wraps and/or protective conduit as required.
MY2150