TM-9-2320-272-24-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4
JUNE 1998
TM-9-2320-272-24-1 - Page 15 of 1015
TM 9-2320-272-24-1
Section II. EQUIPMENT DESCRIPTION AND DATA
l-l2. EQUIPMENT DESCRIPTION AND DATA INDEX
PARA.
NO.
1-13.
1-14.
1-15.
TITLE
Equipment Characteristics, Capabilities, and Features
Location and Description of Major Components
Differences Between Models
PAGE
NO.
1-5
1-16
l-20
1-16.
Equipment Data
1-17.
Description of Data Plates
1-22
l-24
1-13. EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES
a.
The M939, M939A1, and M939A2 (M939/A1/A2) series of vehicles are varied in design and
capabilities. The M939 was a redesign and retrofit of the MS09 series of vehicles, providing enhanced
capabilities.
(1)
The leading features of the M939 are:
(a)
Automatic transmission (Allison MT654)
(b)
Hydraulic-assisted power steering system
(c)
Complete airbrake system
(d)
Improved cooling system
(e)
Three-crewmember cab
(f)
Tilt hood
(2)
Changes were incorporated into later production engines (after engine serial number 11246663)
which provided for control of exhaust gas recirculation back to the air intake manifold and the use of top-
stop injectors to make up a clean air configuration.
(3)
The M939Al improved on the M939 by adding 14:00xR20 super-sized tires, increasing the
minimum road clearance and approach and departure angle. This necessitated a modification to the spare
tire rack and lifting device used on all series vehicles.
(4)
The M939A2 incorporated a new engine (Cummins 6CTA8.3) and the Central Tire Inflation System
(CTIS).
b.
The M939/A1/A2 series vehicles can be distinguished from the M809 series by the following features:
(1)
On the left side, the exhaust was moved behind the cab and tilted out so exhaust gases clear the
side of the vehicle. Hood latches were installed on the sides of the hood near the mirrors. The battery box
was incorporated into the companion seat to improve battery life in cold climates. A steering-assist cylinder
was installed between the right front frame rail and the right axle hub.
(2)
From the front, the hood and fenders are an assembly which tilt forward for access to the engine
compartment. A tilt handle and locking device was installed to tilt and hold the hood in a secured open
position.
(3)
The air filter was moved under the driver’s door and the intake stack was brought up behind the
cab, even with the cab top.
1-5
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