1-7. DESCRIPTION
1-8. The mobile check stand is an open-frame carrier, pivot-plated on two pairs of
wheels mounted with pneumatic tires. Mounting provisions for the models T-62T-2,
and T-62T-2A auxiliary power units are incorporated together with the necessary
electrical and fuel connections between the unit and the check stand components. The
mobile check stand is equipped with a steering towbar and a mechanical hand brake
system. It is weatherproofed to provide protection of critical components from the
elements. The major assemblies mounted on the check stand are: the battery, con-
trol console, thermocouple, tachometer generator, air inlet silencer, exhaust silencer,
speed increaser, and the fire extinguisher. See figure 1-2 for Table of Leading
Particulars.
1-9. ELECTRICAL SYSTEM.
1- 10. The electrical system provides starting power for the APU, and the controls
necessary for automatic operation. The instrument panel and relays, within the con-
trol console, are connected by cables to the battery. Cable connections from the con-
sole attach to the engine control harness receptacle, to the ac generator output power
cable, and to the dc starter-generator for operation of the APU.
1-11. BATTERY. (See figure 1-3.)
1-12. A 24-volt, 34-ampere hour, nickel-cadmium battery, conforming to the require-
ments of Military Specification MS24498-1, furnishes dc power for cranking the APU,
and control power for the electrical controls. The battery is mounted on the right side
of the trailer, confined in a shallow frame (retainer), and secured to the retainer with
studs and clamps. The battery is shipped with electrolyte, and only a slight freshening
charge prior to use is recommended. Bringing the battery up to full charge can be
accomplished during APU checkout operation. Refer to paragraph 7-45 for battery
maintenance procedures.
1-13. CONTROL CONSOLE. (See figure 1-3.)
1-14. The control console is located on the aft, left side of the trailer, and provides a
weatherproof housing for the control system components and the instrument panel. The
check stand control system simulates the aircraft controls. The console is bolted to
two support channels which, in turn, are bolted to the top of the trailer frame. A door
on the console provides easy access to the electrical control system components. The
top of the console houses the instrument panel; a cover, hinged to the console structure,
protects the instrument panel from the elements. Three harness assemblies are con-
nected to the control components. They are: engine control harness, ac generator and
dc generator harness, and the generator set output power harness. The control system
components include a limiter, rectifiers, transformers, relays, contactor, resistors,
voltage regulators, and wire assemblies necessary to automatically control, regulate,
and protect the APU through all phases of operation.
1-2
