page_title: M113 armored personnel carrier
section_title: Basic variants
hierarchical_section_title: M113 armored personnel carrier / Basic variants
context_page_description: The M113 is a fully tracked armored personnel carrier that was developed and produced by the Food Machinery Corp. The M113 was sent to United States Army Europe to replace the mechanized infantry's M59 APCs from 1961. The M113 was first used in combat in April 1962 after the United States provided the South Vietnamese Army with heavy weaponry such as the M113, under the Military Assistance Command, Vietnam program. Eventually, the M113 was the most widely used armored vehicle of the U.S. Army in the Vietnam War and was used to break through heavy thickets in the midst of the jungle to attack and overrun enemy positions. It was largely known as an "APC" or an "ACAV" by the allied forces.
  The M113 was the first aluminum hull combat vehicle to be put into mass production. Much lighter than earlier similar vehicles, its aluminum armor was designed to be thick enough to protect the crew and passengers against small arms fire, but light enough that the vehicle was air transportable and moderately amphibious.
  In the U.S.
context_section_description: M113
  Original version, powered by 209 hp (156 kW) Chrysler 75M V8 gasoline engine.
  M113A1
  Starting in 1964, the gasoline engine was replaced with a 215 hp (160 kW) 6V-53 Detroit Diesel engine, to take advantage of the better fuel economy and the reduced fire hazard of the diesel engine. The suffix A1 was used on all variants to denote a diesel engine, i.e. an M106A1 was an M106 mortar carrier equipped with a diesel engine.
  M113A2
  In 1979, further upgrades were introduced. Engine cooling was improved by switching the locations of the fan and radiator. Higher-strength torsion bars increased ground clearance, and shock absorbers reduced the effects of ground strikes. Armored fuel tanks were added externally on both sides of the rear ramp, freeing up 0.45 cubic metres (16 cu ft) of internal space. The weight of the M113A2 was increased to 11,740 kilograms (25,880 lb). Because the added weight affected its freeboard when afloat, it was no longer required to be amphibious. Four-tube smoke grenade launchers were also added. The suffix A2 is used on all variants to denote upgrade to A2 standard.
  M113A3
  In 1987, further improvements for "enhanced (battlefield) survival" were introduced. This included a yoke for steering instead of laterals, a more powerful engine (the turbocharged 6V-53T Detroit Diesel), external fuel tanks and internal spall liners for improved protection. The suffix A3 is used on all variants to denote upgrade to A3 standard.
  M113 armored cavalry assault vehicle (ACAV) variant
  The "armored cavalry assault vehicle" or "ACAV", was a concept and field modification pioneered by the ARVN in 1963 during the Vietnam War. The ARVN troops utilized the M113 armored personnel carrier as an infantry fighting vehicle, and more often than not, as a light tank by fighting mounted rather than as a "battle taxi" as dictated by U.S. Army doctrine.
  After it was found that the commander and cargo hatch positions were extremely exposed, and hence the commander and troops were vulnerable to enemy fire, South Vietnamese engineers thought out a simple and cheap remedy to this problem: Initially, field expedient shields and mounts were made from sunken ships, but this was soft metal and could be penetrated by small arms fire. Then armor plate from scrapped armored vehicles was used; this worked well, and by the end of 1964 all ARVN ACAVs were equipped with gun shields. For the U.S. Army, ACAV sets were produced industrially in Okinawa for the 12.7 millimetres (0.50 in) machine gun, and rear aft and starboard M60 machine gun positions. Finally, the ARVN's ACAV modifications were adopted by the U.S. Army in Vietnam, and by 1965 the full ACAV set was mass-produced in the U.S. The kit included shields and circular turret armor for the commander's M2 12.7 mm machine gun, and two additional 7.62 mm M60 machine guns, again with shields, fitted on either side of the top cargo hatch. This kit could be retrofitted to any M113. ACAV sets were sometimes fitted to the M106 mortar carrier, but the different rear hatch found on this vehicle required the left M60 machine gun to be fitted to the extreme rear instead of the side. Many kits were added in the field, but at least in the case of the 11th Armored Cavalry Regiment, the vehicles had their ACAV sets installed in the U.S. prior to their deployment to Vietnam in 1966 from Fort Meade, Maryland. Additional armor in the form of a mine protective kit under the hull was also frequently fitted.
caption: M113 ACAV in Vietnam, 1966
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