Lull 944E-42 Service Manual User 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

MU5891