Gama Goat

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M561 Gama Goat
M561 Gama Goat.JPEG
M561 "Gama Goat"
Type 6×6 Cargo
Place of origin United States
Service history
In service 1970s–1990s
Used by United States, Mexico
Production history
Designer Chance-Vought Aircraft
Designed 1962–1966
Manufacturer CONDEC
Unit cost $13,281[1]
Produced 1969–1973
No. built 14,274
Variants M792 Ambulance
Weight 7,275 lb (3,300 kg)
Length 227 in (5.8 m)
Width 84 in (2.1 m)
Height 91 in (2.3 m)
Crew 1

Engine Detroit Diesel 53
160 cu in (2.6 L) Diesel I3
101 hp (75 kW), 217 lbf·ft (294 N·m)
Suspension Wheel 6×6
420 mi (680 km)
Speed 56 mph (90 km/h)

The Gama Goat was a six-wheel drive semi-amphibious off-road vehicle originally developed for use by the US military in the Vietnam War. The Goat used an articulated chassis, so that from distance it appears to be a four-wheel drive vehicle pulling a two-wheel trailer, but it is a single six-wheel vehicle with a four-wheel steering arrangement with the front and rear wheels turning in opposite directions. It was famous for its ability to travel over exceptionally rough and muddy terrain.

The vehicle's nickname came from two sources; "Gama" from the name of the inventor of its powered articulated joint, Roger Gamaunt, and "Goat" for its mountain goat-like off-road ability. Its military designation was M561, 6×6 tactical 1¼-ton truck. There was also an ambulance version known as the M792. The Goat is prized among military vehicle collectors because it is so unusual and in short supply.[citation needed] The vehicle was replaced by a variety of Commercial Utility Cargo Vehicles (CUCV) and Humvees (HMMWV)


The concept for the vehicle came when the French Army reported that the United States Army trucks provided to them were woefully inadequate for the terrain in Vietnam. In 1959, ARPA (now known as DARPA) funded a research project called Project "Agile" to develop a new tactical truck for the Southeast Asia theatre, as well as other projects of interest to the then-looming Vietnam War.

Several companies bid for the contract, including Clark, General Motors and LeTourneau, but on March 15, 1963, the research & development contract was awarded to Ling-Temco-Vought (LTV) aerospace, Dallas, Texas,[2] best known for their combat aircraft (though, actually the company did have some experience in designing ground vehicles, particularly, a predecessor of Gama Goat, but they didn't have the truck assembly lines and production experience comparable to those of the mentioned car manufacturers).[1] The principal competitor to the Goat was a tracked XM571 Articulated Utility Carrier developed by Canadair Ltd. of Montreal (yet another aerospace company,) which eventually lost the contest. The contract for the Goat was completed by LTV at cost of about $8.7 million, more than three times more expensively than when it was awarded.[2]

The vehicle weighed almost three times as much as the originally requested by the military and specified by the operational requirements (2,500 lbs). Field testing has not been completed prior to mass production order has been issued. During the field tests, it has not been able to go 20,000 miles without a breakdown.[3]

Final construction of the vehicles was conducted by the Consolidated Diesel Electric Company (CONDEC) at their factory in Charlotte, North Carolina (on June 11, 1968 the Army awarded them a 3-year contract for 15,274 vehicles, 13,516 Army and 1,758 Marine Corps, at a total price of about $132.1 million, on the same day Detroit Diesel Division of General Motors received $30 million 3-year contract for the engines).[2] CONDEC also had factories in Schenectady, New York, where the Gama Goat was originally manufactured, and in Greenwich, Connecticut, where the parts for the Gama Goat were produced. In the early 1960s, the company moved to Waterbury, Connecticut for a few years, then closed their plants in New York and Connecticut to move to Charlotte, North Carolina for cheaper labor and facilities.

The Gama Goat was replaced by a variety of CUCVs[4] and "Humvees" (HMMWV).[5]


Gama Goat ride at the Muckleburgh Collection

Overall, some 14,274 Gama Goats were built at a cost of US$8,000 each (1965 dollars; equivalent to $60,798 in 2016); this was considered quite high at the time. 12,516 were slated for the US Army and 1,758 for the USMC. While the Gama Goat had exceptional off-road ability, its quirky steering made it hard to handle on pavement, and its tendency to flounder in amphibious operations required drivers to have special training in order to operate it.[citation needed] This meant that it could not be the "general purpose" vehicle the Army had hoped for, and production was halted after the original contract expired.

The air-cooled engine used in the original prototypes overheated in use, and was replaced in the production vehicles with a liquid-cooled Detroit 3-53 Diesel engine. Due to the high-intensity noise from the two-stroke Diesel engine, the drivers required hearing protection.[citation needed] The double hull construction and complex articulated drivetrain made maintenance difficult (the lubrication order alone took around six hours). In service in Vietnam, Gama Goats would often be sent out ahead of other vehicles in order to arrive at their destination at the same time.[citation needed]

While technically listed as amphibious, the Gama Goat's swimming capability was limited to smooth water crossings of ponds, canals and streams due to the very low freeboard and the lack of a propeller.[citation needed] Propulsion in the water was supplied by the six spinning wheels, and bilge pumps were standard equipment. Drivers had to remember to close the hull's drain openings before swimming the vehicles. Some models had extra equipment installed that made them too heavy to swim, such as heavy-duty winches, communications shelters that made them top heavy, or radar gear.

It was designed to be air-transportable and droppable by parachute.

Additional specifications[edit]


  • Roll at center axle: ± 15 degrees
  • Roll at rear axle: ± 30 degrees
  • Pitch at rear axle: ± 40 degrees
  • Wall climb (vertical): 18 in (460 mm)
  • Angle of approach: 62 degrees
  • Angle of departure: 45 degrees
  • Hump angle: 140 degrees


  • Front and rear independent coil springs at each wheel
  • Center single leaf spring and swing axle

Steering system[edit]

  • Type: Mechanical front and rear simultaneously operated
  • Steering ratio: 24:1
  • Turning radius: 29 ft (8.8 m)


  • M561
  • Cargo / personnel (eight troops) carrier
  • TOW ATGM team carrier (originally intended to be a dedicated Anti-Tank variant with its own TOW launching platform)
  • Communications (separate shelter installed in the cargo compartment)
  • Mortar carrier
  • Radar (counter-mortar/artillery system)
  • Radar (FAAR System)
  • M60 Machine gun and mount on passenger fender
  • M792
  • Ambulance

See also[edit]


  1. ^ a b Statement of Dr. J. Ronald Fox, Assistant Secretary of the Army, The Acquisition of Weapons Systems, May 21, 1970, pt. 2, p. 470.
  2. ^ a b c Gama Goat Contract Data by R.F. Keller, Assistant Comptroller General of the United States, Washington, D.C., October 6, 1970, p. 487.
  3. ^ Statement of Hassell B. Bell, Associate Director, Defense Division, Office of the Comptroller General of the United States, May 20, 1970, pp. 394-395.
  4. ^ "Dodge and Chevrolet CUCV". 7 July 2012. Retrieved 18 October 2016. 
  5. ^ Turnbull, Grant (30 September 2014). "End of an icon: the rise and fall of the Humvee". Retrieved 18 October 2016. 
  • SNL G874
  • Doyle, David (2003). Standard Catalog of U.S. Military Vehicles. Kraus Publications. pp. 102–104. ISBN 0-87349-508-X. 
  • Ware, Pat (2010). The World Encyclopedia of Military Vehicles. Lorenz Books. p. 228. ISBN 0-7548-2052-1. 

External links[edit]