JLG 4017PS Service Manual - Manual (Page 156)

Hydraulic System
8-24 3706PS, 3707PS, 4014PS, 4017PS, 33.7, 37.6, 37.7
8.12 BOOM RIDE CONTROL
(3706PS, 3707PS, 33.7, 37.6 & 37.7
- IF EQUIPPED)
8.12.1 General Accumulator Information
The accumulator is a 275 bar (3988 psi) piston type
accumulator.
The pneumatic accumulator 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, forcing
the oil out into the lift side of the lift/lower cylinder.
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 accumulator 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 (1) at the top of the accumulator. The
schrader valve is used for pre-charging and testing the
accumulator.
a. Accumulator 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 lift/lower cylinder to allow the
accumulator 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. Disconnect and cap or plug the hydraulic tube (2) at
the accumulator (3).
6. Remove the two straps (4) securing the accumulator
to the lift/lower cylinder.
7. Remove the accumulator.
8. Wipe up any hydraulic fluid spillage in, on, near and
around the machine, work area and tools.
b. Accumulator Installation
1. Secure the accumulator (5) to the lift/lower cylinder
with the two straps (6) to the proper dimensions:
A. 57,0 ± 0,10mm (2.25 ± 0.375 in)
B. 200,0 ± 0,10mm (7.875 ± 0.375 in)
2. Uncap and connect the hydraulic tube to the
accumulator.
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 8.12.3, “Pre-Charging
Accumulator,” for Accumulator pre-charging
instructions.
MAM1440
1
MAM1430
3 2 4
MAM1460
5
6
B A