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CHAPTER 1 GENERAL INFORMATION AND OPERATING INSTRUCTIONS
NMC-WOLLARD
2021 Truax Blvd. Eau Claire, WI 54703 ● P: 715-835-3151● F: 715-835-6625 ● www.nmc-wollard.com
TML-704H Maintenance Lift Manual No. 310547
1 DESCRIPTION
Actuating and/or holding "Operational (Platform) Safety" switch energizes
Operate Safety Valve SV3, diverting oil from the Power Steering Unit to
directional valve bank SV1/SV2. This action is necessary to provide hydraulic
power for the lift and stabilizer functions.
Actuating either Stabilizer "Up" or "Down" switch energizes solenoid valve
SV2, causing the spool to shift, directing oil to extend (lower) or retract (raise)
the stabilizers as appropriate.
When extending (lowering) the stabilizers, oil under pressure free-ows
through pilot checks PC4, PC5, PC6, and PC7 into blind ends of cylinders
HC2, HC3, HC4, and HC5. Pressure in pilot line of PC3 forces this valve
to open, allowing escaping oil from cylinder rod ends to return to tank via
solenoid valve SV2. When stabilizer pads make ground contact, pressure
rises and trips pressure switch PS-SE at approximately 800 PSI. Pressure
continues to rise to 900 PSI setting of relief valve RV3. Stabilizer pressure
cannot exceed 900 PSI, and from this point, all oil is diverted to tank through
RV3 and. When retracting (lowering) the stabilizers, oil under pressure
free-ows through pilot check PC3 into the rod ends of cylinders HC2, HC3,
HC4, and HC5. Pressure in the pilot lines of PC4, PC5, PC6, and PC7 forces
these valves to open, allowing escaping oil from the blind ends of these
cylinders to return to tank via solenoid valve SV2. Restrictor R1 causes the
left front stabilizer to lag behind the others, causing it to be the last one to
retract. This ensures that all stabilizers are fully retracted before "Stabilizers
Up" limit switch is tripped.
1.4.6 Electrical System
All electrical power is supplied by the unit's alternator/battery system. This
includes starting, control and monitoring, vehicle and platform lighting, and
accessory equipment. The system consists of three main groups:
Instrument Panel Assembly
The instrument panel, located at the operator's station, contains all necessary
controls for the engine, lighting systems, and engine system monitors. The
controls and indicators are grouped and labeled for ease of use and
identication.
Fuses for the control circuits are located on the instrument panel and a
sub-panel underneath the instrument panel. All fuses are labeled as to circuit
and current rating.
Engine Package Assembly
All wiring for the engine package is self-contained and may be unplugged
from the vehicle chassis harness for quick removal of engine/transmission
assembly. A sub-panel on the engine contains the starter and glow plug
(diesel engine) relays and main system and glow plug system power fuses
SEPTEMBER 01, 2015
Property of American Airlines
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