TM-9-2350-311-20-1
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR HULL, POWERPLANT, DRIVE CONTROLS, TRACKS, SUSPENSION, AND ASSOCIATED COMPONENTS
AUGUST 1994
TM-9-2350-311-20-1 - Page 23 of 1275
TM 9-2350-311-20-1
1-11 NUCLEAR HARDNESS
Not applicable.
1-12 SECURITY MEASURES FOR ELECTRONIC DATA
Not applicable.
SECTION Il. EQUIPMENT DESCRIPTION AND DATA
1-13 CAPABILITIES AND FEATURES
NOTE
Refer to TM 9-2350-311-10 for further equipment description and data.
1-13.1 Electrical System
M109A2/M109A3/M109A4/Ml109A5
Howitzers’ electrical power is provided through a 24-Vdc (nominal) generating
system consisting of the following components (Chap 8):
a. Four 12-Vdc (nominal) batteries connected in series/parallel that provide 24 Vdc (nominal) to the master relay.
b. M109A2/M109A3 Howitzers have 3-phase, 100-amp alternator that maintains 24-Vdc (nominal) electrical
power through the voltage rectifier, voltage regulator, and to the master relay for systems operation. M109A4/
M109A5 Howitzers have a 3-phase, 180-amp alternator.
c. Master relay that delivers electrical power to electrically operated systems/equipment in M109A2/M109A3/
M109A4/M109A5 Howitzers (hull and cab) by turning on the MASTER switch. The MASTER switch, located on
the driver’s portable instrument panel, actuates the vehicles’ electrical system. With the powerplant off (engine
not running), activation of the MASTER switch provides delivery of electrical power direct through the
alternator, voltage rectifier, voltage regulator, and master relay circuit.
1-13.2 Powerplant (Engine and Transmission)
The powerplant (engine and transmission) provides the mobility for M109A2/M109A3/M1 09A4/M109A5
Howitzers. The
powerplant consists of the following subsystems:
a. Two engines are available:
• Detroit Diesel 8V71T, model 7083-7396, diesel, liquid-cooled, V-8 engine, which generates
405 horsepower at 2300 rpm.
• Detroit Diesel 8V71T, model 7083-7391, diesel, liquid-cooled, V-8 engine, which generates
440 horsepower at 2300 rpm.
1-9
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