Lull 944E-42 Service Manual - Manual (Page 143)

8-27 944E-42
Hydraulic System
a. Auxiliary Hydraulic Pressure Release Valve
Removal
1. Park the machine on a firm, level surface, level the
machine, 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. Properly disconnect the batteries.
5. Remove the access plate from the floor of the cab.
6. Label, disconnect and cap all hose attached to the
auxiliary hydraulic pressure release valve (16).
7. Label or mark the wire harness connector attached
to the auxiliary hydraulic pressure release valve.
Disconnect electrical connector.
8. Remove the two capscrews and washers from the
auxiliary hydraulic pressure release valve and
remove the valve.
b. Auxiliary Hydraulic Pressure Release Valve
Disassembly, Inspection and Reassembly
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.
1. Remove all fittings from the release valve (1), noting
the location and orientation of each fitting.
2. Remove the solenoid cartridge (2) from the block.
3. Clean all components with a suitable cleaner before
inspection.
4. Inspect internal passageways of the release valve
and it’s component parts for wear, damage, etc. If
inner surfaces of the pilot select valve DO NOT
display an ultra-smooth, polished finish, or
components are damaged in any way, replace the
pilot select valve or appropriate part. Often, dirty
hydraulic fluid causes failure of internal seals and
damage to the polished surfaces within the release
valve.
5. Secure the release valve in a bench vise or by other
suitable means.
6. Install the fittings to there proper locations.
7. Install the solenoid cartridge (2) and torque the
cartridges to 20 lb-ft (27 Nm). Torque the solenoid
nut to 5 lb-ft (7 Nm).
c. Auxiliary Hydraulic Pressure Release Valve
Installation
1. Position the release valve back onto the valve plate.
Install and tighten the two capscrews.
2. Uncap and reconnect the previously labeled
hydraulic hoses.
3. Reconnect any electrical connections to the
appropriate locations.
4. Properly connect the batteries
5. Start the machine and run at approximately one-third
to one-half throttle for about one minute without
moving the machine or operating any hydraulic
function.
MU5841
B
A
16
MU5891
1
2