TM-9-2350-311-10 M109 Operator's Manual for M109A2, M109A3, M109A4 and M109A5 Download
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TM 9--2350--311--10 1--19 1--12 DIFFERENCES BETWEEN MODELS — CONTINUED k. Cab hydraulics. M109A4/M109A5 howitzers have a hygroscopic breather and an air line filter mounted to rear interior that provides added filtering of hydraulic fluid. l. Combat override switch. M109A4/M109A5 howitzers have a combat override switch mounted to back wall below chief of section’s seat. m. NATO slave start receptacle. M109A4/M109A5 howitzers have a NATO slave start receptacle located in the driver’s compartment. All M109A2/M109A3 howitzers have a NATO slave start receptacle located in the battery compartment. n. Air cleaner neutral safety switch. M109A4/M109A5 howitzers have a safety switch in the driver’s compartment with a neutral position that prevents the air cleaner blowers from running continuously as in M109A2/M109A3 howitzers. o. Crew compartment subfloor drains. M109A4/M109A5 howitzers have 13 subfloor drains to provide drainage of DS2 (from NBC decontamination process) and drainage of excess water. p. External power receptacle. M109A4/M109A5 howitzers have external power receptacle located on the rear bulkhead. q. Mount. M109A2/M109A3/M109A4 howitzers have M178 mount. The M109A5 howitzers have M182 mount. r. Cannon assembly, howitzer. M109A2/M109A3/M109A4 howitzers have M185 cannon assembly. M109A5 howitzers have M284 cannon assembly. This configuration provides the M109A5 howitzer with extended range capability. s. Firing Mechanism. M109A2/M109A3/M109A4 howitzers use the M35 firing mechanism. M109A5 howitzers use the M49 firing mechanism. t. Torque key. M109A2/M109A3/M109A4 howitzers with the M178 mount assembly have torque keys with one keyway which measures approximately 31/32 inch (24.6 mm) and are held in place with ten cap screws and lockwashers. M109A5 howitzers with the M182 mount assembly have torque keys with two keyways which measure approximately 1--9/16 inches (3.97 cm) and are held in place with eight cap screws and lockwashers. u. Hull rear doors. Earlier versions of the howitzer have double doors, later versions have single doors. v. Personnel heater exhaust deflector. There is no personnel heater exhaust deflector on earlier versions of the howitzer. Later versions have exhaust deflectors mounted on the exhaust grille. w. Primary fuel filters. The primary fuel filters, in earlier versions of the howitzer, are positioned near the engine vibration damper and engine oil pan. Later versions have the primary fuel filters positioned near the oil filters, attached to the transmission. x. External telephone terminals. The M109A2/M109A3 telephone terminals are located on the hull rear bulkhead. The M109A4/M109A5 telephone terminals are located on the hull rear roof. y. Generator and charging system. The M109A2/M109A3 howitzers are equipped with a 100 ampere generator. The M109A4/M109A5 howitzers have a 180 ampere generator.