Lull 944E-42 Service Manual - Manual (Page 215)

10-3 944E-42
Stabil-TRAK™ System
10.2 STABIL-TRAK™ DESCRIPTION
The patented rear axle lock or Stabil-TRAK™ system
works to stabilize the machine under various conditions.
The appropriate Operation & Safety manual contains
basic Stabil-TRAK™ information; a copy of the Operation
& Safety manual should always be available in the
storage compartment located on the left inside wall of the
cab, next to the seat support.
The Stabil-TRAK™ lock system will be activated when
the boom angle is greater than 40° and one or more of the
following functions are activated:
• Engaging the Parking Brake Switch
• Placing the Travel Select Lever in (N) NEUTRAL
• Depressing and holding the Service Brake
With the boom lowered to an angle of less than 40°, the
rear axle lock system is not active and none of these
functions will affect the Stabil-TRAK™ system.
10.2.1 Stabil-TRAK™ Solenoid Valves
There are five Stabil-TRAK™ solenoid valves installed in
the Stabil-TRAK™ manifold, attached to the stabilizer
cylinder above the left side of the rear axle.
If a solenoid valve is suspected of malfunctioning,
disconnect the coil wiring lead and test the coil for proper
resistance (7-9 ohms) and for proper voltage from the
harness (12 VDC). Replace the solenoid coil if open or
shorted to ground.
Also inspect the valve cartridge, o-rings, and the other
hydraulic and electrical components in the circuit to
accurately determine the cause of the problem.
All solenoid coils are identical and can be interchanged
for diagnostic purposes.
Note: DO NOT interchange solenoid valves 4A (1),
4B (2), 12A (3) or 12B (4) with solenoid valve 3 (5).
These valves will fit into the other locations, but are
configured differently internally and will not operate
properly if interchanged.
Cartridge valves 4A (1), 4B (2), 12A (3) and 12B (4) are
identical and can be interchanged for diagnostic
proposes.
Note: Make sure the 0.060 orifices are in place when
installing solenoid valves 4A (1) and 4B (2).
In general, if there is a problem with the Stabil-TRAK™
system beyond common electrical troubles, the involved
electrical and hydraulic circuits should each be checked
and the exact source of the problem diagnosed before
any parts are replaced.
MT3132
1
2
4
3
5