M107 Self-Propelled Gun

M107 self-propelled gun
An Israeli M107 self-propelled gun in Latrun
Type	Self-propelled artillery
Place of origin	United States
Service history
Wars	Vietnam War Yom Kippur War Iran–Iraq War
Production history
Manufacturer	FMC Corp., Bowen-McLaughlin-York, General Motors Corp. (transmission)
Specifications
Weight	Combat: 28.3 metric tons (62,400 lb)
Length	Hull: 6.46 m (21 ft 2 in) Overall: 11.30 m (37 ft 1 in)
Barrel length	L/60
Width	3.15 m (10 ft 4 in)
Height	3.47 m (11 ft 5 in)
Crew	13 (vehicle capacity 5)
Caliber	175 mm (6.9 in)
Elevation	−5° to +65° deg.
Traverse	60°
Rate of fire	Rapid: 1 rpm Regular: 1/2 rpm
Maximum firing range	40 km (25 mi)
Main armament	1 × 175 mm M113 or M113A1 Gun
Engine	General Motors 8V71T; 8 cylinder, 2 cycle, vee, supercharged diesel 405 hp
Suspension	torsion bar
Ground clearance	44 cm (1 ft 5 in)
Operational range	720 km (450 mi)
Speed	80 km/h (50 mph)

The M107 175 mm self-propelled gun was used by the U.S. Army from the early 1960s through to the late 1970s. It was part of a family of self-propelled artillery that also included the M110. It was intended to provide long-range fire support in an air-transportable system. It was exported to several other countries including Germany, South Korea, Spain, Greece, Iran, Israel, Italy, the Netherlands, the United Kingdom, and Turkey. The M107's combat history in U.S. service was limited to the Vietnam War; it also saw extensive combat use in Israeli service. The M107 shared many components with, and in many cases was replaced by, later versions of the M110 8" howitzer. Although withdrawn from U.S. service in the late 1970s, it continues in service with some armies as of 2010.

During the 1950s, the standard U.S. Army motorized 203mm artillery piece was the M55, based on the chassis and the turret of the M53 155mm self-propelled gun, which used some components from the M48 tank. The weight of the M55, at 44 metric tons, prohibited air transportation and its gasoline engines limited its range to approximately 260 km, as well as presenting an explosion hazard in combat.

This led the U.S. Army to issue a requirement for a new series of self-propelled artillery: lighter, so as to be transportable by air, while continuing the practice of deriving several vehicles from the same chassis, which simplified maintenance and training. The Pacific Car and Foundry (Paccar) company developed several prototypes. The 175 mm T235 self-propelled gun and 203 mm T236 self-propelled howitzer were driven by a diesel engine and, aside from the different armament, were essentially the same vehicle. They were introduced into U.S. Army service as the M107 and M110 in 1962 and 1963, respectively.

Paccar received the M107 and M110 design contracts and initial manufacturing single source bid from Detroit Arsenal. This was based on patented key features of the M55: the gas equalibrator [2911209] balance of the barrel that hydraulically trimmed with terrain fall line sensing pendulum [2857815], no back pawl limits on aiming, parabolic taper hydraulic recoil cylinders [not patentable], and hydraulic lock out of suspension when shooting [3117800]. Two other firms also produced the M107: FMC, between 1965 and 1980, and Bowen-McLaughlin-York.