Lull 944E-42 Service Manual - Manual (Page 139)

8-23 944E-42
Hydraulic System
8.7.4 Pilot Select Valve (Dual Joystick)
Pilot pressure from the front joystick flows to the pilot
select valve (15). The pilot pressure is then directed to the
auxiliary hydraulic section of the main control valve or to
the transfer carriage section of the main control valve.
The direction of the flow is controlled by the two solenoid
cartridges (16) on the valve. The solenoid cartridges are
controlled by the push button on top of the joystick.
The pilot select valve is located on the valve plate which
is located under the cab floor.
a. Pilot Select 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. Remove the access plate from the floor of the cab.
5. Label, disconnect and cap all hydraulic hoses
attached to the pilot select valve (15). Cap all fittings
and openings to keep dirt and debris from entering
hydraulic system. Label and disconnect the wire
harness connectors as they relate to the pilot select
valve.
6. Remove the two cap screws (17) holding the pilot
select valve and remove the valve.
b. Pilot Select 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 pilot select valve (1),
noting the location and orientation of each fitting.
2. Remove the two solenoid cartridges (2) from the
valve.
3. Clean all components with a suitable cleaner before
inspection.
4. Inspect internal passageways of the pilot select
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 pilot
select valve.
5. Secure the pilot select valve in a bench vise or by
other suitable means.
6. Install the fittings to there proper locations.
7. Install the two solenoid cartridges and torque the
cartridges to 20 lb-ft (27 Nm). Torque the solenoid
nuts to 5 lb-ft (7 Nm).
c. Pilot Select Valve Installation
1. Position the pilot select 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.
MU4021
15
16
17
MU4051
1
2