Secure the load to the rails. Also,
check that the rail stop assemblies are up.
Connect the trailer to a tow vehicle.
Release the trailer brakes and tow
the trailer to the work site.
Set the trailer brakes and unhook
To unload by sliding the load off,
release the securing device and slide toward the rail
Pull the rail stop assemblies down
when the load is near the stops and ready to the
Slide the load off.
maintenance manual. The following general operator
inspections should be made on the engine trailer.
Visual inspection. Look over the
entire trailer for obvious discrepancies, such as loose or
missing hardware or flat tires.
Tires. Visually check for apparent
correct pressure. If in doubt, check with a gauge.
Brakes. Check that they set and
release without sticking.
Maintenance. Consult the applicable
maintenance manual for scheduled and preventive
Adapters available. The adapters that can
be used with the trailer allow it to be used with many
different types of engines. Consult the applicable
maintenance manual for the engine repaired locally.
Aviation Ground Power Unit. The aviation
ground power unit, shown in figure 9-13, is a gas turbine
engine-driven, wheel mounted, self-propelled (up to 3
mph on flat surface), enclosed unit. The APGU can be
towed (20 mph maximum), and is air transportable.
Purpose. The aviation ground power unit
provides ac/dc electrical, hydraulic, and pneumatic
power. Power is available individually, or in any com-
bination. The AGPU provides the ground power
requirements for aircraft.
Principles of Operation. Control and regulation
of the AGPU electrical and pneumatic systems is
semiautomatic. Electronic devices monitor and regulate
electrical voltage, frequency, and current; as well as
pneumatic outputs. Control of the hydraulic system is
semi-automatic, in that the operator must set hydraulic
pressure, and select operating modes.
Engine/Gearcase. The gas
turbine engine (GTE), provides pneumatic power, and
shaft power to drive an ac/dc generator and a hydraulic
pump. The generator and pump are mounted on pads
on the gearcase. Once started, the engine runs up to
100 percent governed speed of 58,737 rpm, and
automatically maintains that speed until shutdown.
Engine air intake is through an air cleaner/duct
assembly to the engine. Engine exhaust is through an
exhaust ejector, and out the roof through an exhaust
Starting system. The accumulator
of the mobile servicing unit is filled with a nitrogen
precharge. The hand pump, acting on hydraulic fluid
drawn from the reservoir, builds up pressure in the
accumulator for the initial diesel engine start. When the
start valve is depressed, the pressurized fluid flows to
the inlet of the starting motor to crank the engine. The
fluid then returns to the reservoir. The accumulator
charging pump pumps hydraulic fluid from the reservoir
to charge the accumulator after the engine has started.
Propulsion System. The propulsion
system provides suspension, steering, brakes, and drive
power for the AGPU. A speed/direction control
assembly mounted on a tow bar allows the operator to
control the forward/reverse directions and speed (up to 3
mph on flat surface)in self-propulsion mode. The tow
bar is also used to steer the AGPU when using self-
propulsion mode. Drive power is provided by a dc
assembly. An electric brake assembly is provided. The
electric brake prevents the rear wheels turning with the
clutch engaged until electrical power is applied to the
traction motor and electric brake. Application of dc
drive power to the traction motor is controlled by a
motor controller and relays located on the upper tray in
the electrical compartment. The motor controller
receives signals from the speed/direction control
assembly. The drive train consists of a gear box, a
chain drive, a manual clutch, and a rear axle assembly.
A dead man switch on the speed/direction control
assembly must be held in while operating the propulsion
system. If the switch is released (intentionally or