JLG 4017RS Service Manual - Manual (Page 145)

8-15 3614RS, 4017RS
Hydraulic System
a. Outrigger/Stabilizer Valve Removal
1. Park the machine on a firm, level surface, level the
machine, fully retract the boom, raise and support the
boom, place the transmission in (N) NEUTRAL, engage
the park brake, lower each outrigger and shut the engine
OFF.
2. Place a Do Not Operate Tag on both the ignition key
switch and the steering wheel.
3. Open the engine cover. Allow the system fluids to cool.
4. Properly disconnect the battery.
5. Remove the access cover from the top front of the
frame.
6. Label, disconnect and cap the hydraulic hoses and the
electrical plugs connected to the outrigger/stabilizer
valve.
7. Remove the nuts holding the outrigger/stabilizer valve
to the frame.
8. Remove the outrigger/stabilizer valve from the
machine. Wipe up any hydraulic fluid spillage in, on,
near and around the machine.
b. Outrigger/Stabilizer Valve Disassembly, Cleaning,
Inspection and Assembly
1. Place the outrigger/stabilizer valve assembly on a
suitable work surface.
2. Separate the outrigger/stabilizer valve solenoids from
the spool. Discard the o-rings.
3. Clean all components with a suitable cleaner before
inspection.
4. Inspect the solenoid cartridges 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 steer select 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 secondary function
manifold.
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 solenoids in the outrigger/stabilizer valve
housing.
c. Outrigger/Stabilizer Valve Installation
1. Install the outrigger/stabilizer valve to the frame using
the previously removed nuts and washers.
2. Connect all the hydraulic hoses, fittings, solenoid wire
terminal leads, etc., to the outrigger/stabilizer valve
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 hose clamps.
4. Properly connect the battery.
5. Remove boom support.
6. 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.
7. 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.
8. Wipe up any hydraulic fluid spillage in, on, near and
around the machine, work area and tools.
9. Install the previously removed access cover.
10. Close and secure the engine cover.
11. Remove the Do Not Operate Tag from the ignition key
switch and the steering wheel.
d. Outrigger/Stabilizer Valve Test
Refer to Section 8.5.1, “Hydraulic Pressures.”
1. Conduct a pressure check of the outrigger/stabilizer
valve hydraulic circuit.
2. Check each outrigger/stabilizer valve mode for proper
function.
8.9.7 Brake Damper
The brake damper is a 250 bar (3626 psi) diaphragm damper.
The pneumatic damper is operated by compressed gas. Gas
and hydraulic oil occupy the same container. When oil
pressure rises, incoming oil compresses the gas. When oil
pressure drops, the gas expands.
The gas is separated from the oil by a piston. This prevents
the mixing of gas and oil and keeps gas out of the hydraulic
system.
The damper must be “pre-charged” with gas before use in
the hydraulic system. This is done by filling the gas chamber
with dry nitrogen to a pressure of 35 bar
(507 psi). The schrader valve is located under the protective
cap at the top of the damper. The schrader valve is used for
pre-charging and testing the damper.