Lull 944E-42 Service Manual - Manual (Page 141)

8-25 944E-42
Hydraulic System
8.7.6 Single Joystick Pilot Select Valve
Pilot pressure from the joystick flows to the single joystick
pilot select valve (10). The pilot pressure is then directed
to the appropriate section of the main control valve. The
direction of the flow is controlled by the solenoid
cartridges (11) on the valve. The solenoid cartridges are
controlled by holding the trigger button down on the
joystick or by pushing the thumb button up or down.
The single joystick pilot select valve is located on the
valve plate which is located under the cab floor.
a. Single Joystick 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. Properly disconnect the batteries.
5. Remove the access plate from the floor of the cab
and right console side panel access panel.
6. Label, disconnect and cap all hose attached to the
single joystick pilot select valve (10). Label or mark
any wire harness connectors as they relate to the
single joystick pilot select valve.
7. Remove the two capscrews on the single joystick
pilot select valve and remove the valve.
b. Single Joystick 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 six solenoid cartridges (2&3)and the
pressure reducing cartridge from the block.
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 four solenoid cartridges (2) and torque the
cartridges to 20 lb-ft (27 Nm). Torque the solenoid
nuts to 5 lb-ft (7 Nm).
8. Install the other two solenoid cartridges (3) and
secure with two capscrews (4) each. Torque the
capscrews to 2.5 lb-ft (3 Nm).
9. Install the pressure reducing cartridge (5) and torque
to 25 lb-ft (33 Nm).
MU5631
10
11
MU5651
T
CT
A
P
CTB
HB
HA EB
EA AUX2
AUX1 TB
TA
CTA
TR
CTB
HO
EXT
AX
T1
1
2
3
5
4