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 28 of 1275
TM 9-2350-311-20-1
1-15 DIFFERENCES BETWEEN MODELS
Differences between models exist (1) when comparing the M109A2 and M109A3 Howitzers; (2) when comparing one
M109A3 to another M109A3 Howitzer
and (3) when comparing the M109A2/M109A3 and M109A4/M109A5 Howitzers.
1-15.1 Hull Rear Doors
The hull rear doors differ among the howitzers. Earlier versions have double doors and later versions have single doors.
All M109A2 Howitzers have single doors (para 11 -12).
1-15.2 Personnel Heater Exhaust DefIector
There is no personnel heater exhaust deflector on earlier howitzers. All later howitzers and all M109A2 Howitzers have
the personnel heater exhaust deflectors mounted on the exhaust grille.
1-15.3 NATO Slave Start Receptacle
At present, not all of the M109 Howitzers have NATO slave start receptacles. Also, the slave start receptacle location
differs between the M109A2/M109A3 and M109A4/M109A5 Howitzers. The M109A2/M109A3 NATO slave start
receptacle is located in the battery compartment. The M109A4/M 109A5 NATO slave start receptacle is located in the
driver’s compartment (para 8-38).
1-15.4 Primary Fuel Filters
The primary fuel filters are located in different areas of the engine compartment. Some earlier howitzers’ primary fuel
filters are positioned near the engine vibration damper and the engine oil pan. The later howitzers’ primary fuel filters are
positioned near the oil filters attached to the transmission (vehicle front) (para 6-6).
1-15.5 Travel Locks
There are some travel lock differences involving the spring anchors. Differences are minor and are shown in paragraph
11-14.
1-15.6 Ventilated Face Piece System (VFPS)
M109A4/M1 09A5 Howitzer hulls have a VFPS consisting of two air heaters, an air purifier, and required hoses.
1-15.7 Telephone Terminals
The location of vehicle telephone terminals differ on M109A2/M109A3 and M109A4/M109A5 Howitzers. The M109A2/
M109A3 terminals are located on the hull rear bulkhead. M109A4/M109A5 terminals are located on the hull rear roof
(exterior).
1-15.8 External Power Receptacle
M109A4/M109A5 Howitzers have external power receptacles located on the rear hull bulkhead.
1-15.9 Alternator and Charging System
M109A2/M109A3 Howitzers have 100-amp alternators/rectifiers. M1 09A4/M1 09A5 Howitzers have 180-amp
alternators/rectifiers. The location for both configurations is the same.
1-14
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