JLG 4017RS Service Manual - Manual (Page 146)

Hydraulic System
8-16 3614RS, 4017RS
a. Damper Removal
1. Remove any attachment from the machine. Park the
machine on a firm level surface and fully retract the
boom. Raise the boom to allow sufficient work space
around the frame to allow the damper to be removed.
Support the boom. Place the travel select lever in (N)
NEUTRAL, engage the park brake, shut the engine OFF
and chock wheels.
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. Pump the brake pedal several times to dissipate any
excess pressure in the brake system.
6. Disconnect and cap or plug the hydraulic hose (5) at the
damper (6).
7. Remove the two straps (7) securing the damper to the
mounting bracket.
8. Remove the damper.
9. Wipe up any hydraulic fluid spillage in, on, near and
around the machine, work area and tools.
b. Damper Installation
1. Secure the damper (6) to the mounting bracket with the
two nylon straps (7).
2. Uncap and connect the hydraulic hose (5) to the
damper.
3. Remove the boom support.
4. Properly connect the battery.
5. Close and secure the engine cover.
6. Remove the Do Not Operate Tag from the ignition key
switch and the steering wheel.
7. Refer to Section 8.9.9, “Pre-Charging Damper,” for
damper pre-charging instructions.
8.9.8 Brake Damper Charging
This section covers the charging of the damper system.
The damper is located and mounted at the front of the
machine, between the frame rails. The internal parts of the
damper are not serviceable. If the internal piston is leaking,
or the seals on the top or bottom cap are leaking, the damper
requires replacement.
The damper pre-charge pressure will vary depending on the
ambient temperature that the damper was pre-charged at
and the actual operating temperature of the damper.
8.9.9 Pre-Charging Damper
Note: Replacement damper are not pre-charged when
shipped.
Pre-charge the damper with nitrogen gas only. Nitrogen gas
is free of water vapor and oxygen which makes it harmless to
internal parts and will not react if mixed with oil under
pressure.
Never charge an damper to a pressure more than specified.
The proper pressure for the damper is
35 bar (507 psi).
Note: Make sure the nitrogen bottle, as well as the charging
and gauge assembly used is compatible with the schrader valve
assembly on the damper. The nitrogen bottle and all
components must be rated for a pressure at least as high as the
nitrogen source. It is strongly recommended that the nitrogen
bottle has a high pressure regulator.
A damper fill kit is required to properly charge the damper.
Refer to the parts manual
or contact the local JLG dealer.
MZ8090
5
6
7
WARNING
NEVER fill an damper with oxygen! An explosion could
result if oil and oxygen are mixed under pressure. Only fill
damper with dry nitrogen.
NOTICE
Never fill an damper with air. Air contains moisture which can
cause corrosion. This corrosion may damage seals and ruin
the damper.