During World War II, the M3 proved to be a versatile workhorse, and eventually over more than 41,000 vehicles in no less than 70 versions were produced. Later, improved models of the M2 and M3 were designated M9 and M5. Production stopped in 1944, but the Half-Track remained in service until early 1950s. (source)

INTRODUCTION (from Roberts Armory)
A half-track is a vehicle that utilizes both tracks and wheels as running gear. The half-track was conceived by the Russians around 1914 but successfully developed by the Citroen Company in France. The U.S. Army purchased a license to develop half-tracks and experimented with half-track adapters. These were track units that could be retrofitted to existing vehicles. The mobility of the vehicle improved markedly when using these adapters. The scout car M3 was retrofitted with tracks culminating in the classical design as shown above. Half-tracks were built by White Motor Company, Diamond-T Motor Company, Autocar Company and International Harvester.

ENGINEERING CHARACTERISTICS

The M16 is the anti-aircraft version of the M3 troop carrier. 5 more pictures of the AAM16 courtesy of the A.F.C.V.M (French Association of Military Vehicles Collectors)

The basis of the half-track was a truck chassis and drive train. An armored box was placed in the back to provide protection for personnel and armament. This vehicle was equipped with a ditch roll which helped in traversing obstacles. Some vehicles were equipped with a winch in place of the ditch roll. Radiator louvers were used during battles to protect the radiator from small arms fire. The 4 speed transmission, combined with a 2 speed transfer case yielded 8 speeds forward with two in reverse. The levers to the right of the shift lever select high and low range and front wheel drive. The center seat is the jump seat, usually for the gunner. The track is constructed of two steel cables with rubber track molded around them. The rubber gives flexibility to the track while the cables are for reinforcement. The rear idler is used to adjust track tension. The power plant is a White 160 AX, 6 cylinder engine.

USE IN WORLD WAR II
The U.S. half-track was first used in the Philippines where several initial design problems arose. The suspension was modified for increased reliability, but one of the main criticisms, the lack of overhead armor, was never changed throughout the life of the vehicle since the added weight decreased mobility. After the surrender of Bataan, several half-tracks were utilized in the Japanese army. In North Africa the half-track was improved with heavier road wheel springs and heavier springs for the rear idler. During the battle of the Kasserine Pass, several half-tracks were captured and used by the Germans. At the time of the invasion of Sicily, the half-track had settled into its role as an armored infantry transport vehicle that was able to deliver infantry closer to the battle since they were less vulnerable to rifle fire. The vehicle would hold supplies and infantry field equipment, leaving the infantry unencumbered by heavy field packs. The half-track was highly mobile and could follow tanks quite easily, unlike trucks which were more at home on the road. The half-track was often criticized as too lightly armored, but this could partially be attributed to abuse of the vehicle. Some units used the half-track as an armored assault vehicle which was not its role by design. The M2 and M3 half-tracks, the machine gun/armored personnel carrier versions of the vehicle, were widely used in the European theater. The German SdKfz 251 half-track was similar to the American half-track. The 251 had better armor protection, but the U.S. half-track had superior mobility with more horsepower, a driven front axle and a ditch roll. Half-tracks were also used as gun motor carriers or gun carriages, the most common being the gun motor carriage (tank destroyer), the Howitzer motor carriage, the mortar motor carriage and the multiple gun anti-aircraft motor carriage. The tank destroyer version of the half-track was marginally successful and eventually was replaced by the Sherman chassis based tank destroyers such as the M10. The M16 quadmount version of the half-track proved very successful and became the standard light anti-aircraft armored vehicle. Over 30,000 vehicles were produced during the war. (source1, source2)

information courtesy of: A.F.C.V.M.,WWII Vehicles, 555th AAA AW Battalion
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A.F.C.V.M.-- WWII Vehicles -- 555th

read about the M16 at Roberts Armory
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