Powerplant The powerplant is composed of the
Continental Model AVDS-1790-2DR air-cooled, 12-
cylinder, diesel engine and the Allison (GM) Model XT-
1410-4 cross-drive transmission. The powerplant is
removed and installed as a unit. Separation of engine
from transmission center section is performed after the
powerplant has been removed from the vehicle. The
powerplant supplies electrical power through a generator
and motive power through the output reduction units.
Fuel System. The fuel system includes liquid fuel
(diesel) storage and delivery system. Fuel storage
consists of three separate fuel tanks. Fuel is fed to the
engine by an electric pump through a system of hoses
and valves. Fuel is strained at the tank filler openings as
the tanks are filled, and filtered through separate and
renewable filter elements as it is fed to the engine.
Combustion air is cleaned by two air cleaners and driven
Fuel Tanks. All tanks are of a welded steel
construction. The left rear tank contains the filler cap and
filter assembly. Fuel level sending units are contained
within the right rear and forward tanks. An electric fuel
pump is located in the forward fuel tank sump cavity,
allowing complete drainage of the tank before tank
removal. All tanks are interconnected and shock
mounted. Grounding straps are provided to assure
Fuel Pump. The electric fuel pump located in the
forward fuel tank sump cavity is a centrifugal pusher-type
hermetically sealed and contains a 24-volt dc motor to
operate the pump. A strainer is provided as an integral
part of the pump assembly for efficient fuel filtering. The
fuel pump is shock mounted in a support assembly
which suspends the pump in the fuel tank and also
provides a housing for fuel and electrical connections.
Purge Pump. The purge pump (fig. 3-8) handle
is located on the floor to the left of the drivers position.
The purge pump is used to pump air from the fuel lines
and to facilitate engine starting in cold weather.
Vehicle Electrical Systems.
Main Engine Generator System. During
periods of main engine operation, the vehicle electrical
system derives its power from a 300-ampere, 28-volt dc
generator and is driven by the main engine. This
generator also serves to charge the vehicle batteries
during periods of main engine operation.
The vehicle battery system consists of six 12-volt,
100-ampere-hour batteries connected in series-parallel
to supply 24 volts dc to the electrical system when the
generator is not running. A solid state voltage regulator
serves to maintain a constant generator output voltage of
28 +0.7 volts dc when the generator is powering the
electrical system and charging the vehicle batteries.
Control of the electrical system is maintained by the
driver through a series of instruments and switches
mounted on control panels in the drivers area. A system
components of the vehicle electrical system. Waterproof
(2) Auxiliary Generating System.
generating system consists of a dc voltage generator
(fig. 4-1) driven by a diesel engine. A solid-state voltage
regulator serves to maintain a constant generator output
voltage of 28 ± 0.7 volts dc when the generator is
powering the system and charging the batteries. This
voltage regulator has an internal current limiting circuit
which the APU generator interpole (APU regulator plug
pin E) voltage to 0.48 + 0.03 vdc. This corresponds to a
nominally regulated generator output of 160 amps dc,
with a maximum generator output of 180 amps dc.
(3) New Dual Voltage Regulator System. The main
and auxiliary engine can be operated together or
individually as desired to recharge the vehicle batteries.
With the new dual voltage regulator system,
during periods of cold weather starting, the auxiliary
engine can now be started and left running to aid the
vehicle battery charge condition, while attempting to start
the main engine.
1-12 CHANGE 7