2-1. GENERAL. The 5-ton, 6x6, M39 series trucks are tactical trucks, designed
for use on all types of roads, highways, and cross-country terrain. They will ford
hard bottom water crossings up to 30 inches deep without special fording equipment.
Three basic wheelbase chassis are available for mounting various body types, (cargo,
dump, medium wrecker and tractor) . The following paragraphs are provided to give
the operator an overall understanding of the equipment and its main functions. The
descriptive text is keyed to an overall equipment block diagram , which shows each
functional group of the equipment as a block. Arrows are used to show the flow of
power to and from each functional block on the diagram.
This vehicle has been designed to operate safe-
ly and efficiently within the limits specified in
this TM. Operation beyond these limits is
prohibited IAW AR 70-1 without written ap-
proval from the Commander, U.S. Army Tank-
Automotive Command, ATTN: AMSTA-CM-S,
Warren, MI 48397-5000.
EQUIPMENT FUNCTIONAL DESCRIPTION. (See Fig. 2-1. )
E n g i n e The engine supplies power to move the truck and operate equipment
b. Clutch . The clutch by means of mechanical linkage, joins power produced by
the engine, to the transmission. The clutch also separates power from the transmis-
sion when not needed, or while shifting transmission gears.
c. Electrical System. The 24 volt electrical system supplies electrical current to start the
engine, operate lights, equipment and accessories, and to charge the batteries.
d. Fuel System. The fuel system stores fuel in the tanks, delivers fuel to the
engine, as required, and returns excess fuel to the tanks.
e. Cooling Svstem. The cooling system removes excess heat produced while the
engine is running, and keeps the engine at normal operating temperature. The
cooling system also supplies heat to warm the cab or personnel compartment, when
f. Exhaust System. The exhaust system collects and removes exhaust gases
produced when the engine is operating.
. Transmission System. The transmission system gives the operator a choice of
five forward gear combinations (speeds) , reverse, and neutral position for best
operation of the truck at all speeds and conditions.