M3 half-track


The M3 half-track was an American armored personnel carrier half-track widely used by the Allies during World War II and in the Cold War. Derived from the M2 half-track car, the M3 was extensively produced, with about 15,000 standard M3s and more than 38,000 variant units manufactured.
The M3 was extensively modified with several dozen variant designs produced for different purposes. During World War II, the M3 and its variants were supplied to the U.S. Army and Marines, as well as British Commonwealth and Soviet Red Army forces, serving on all major fronts throughout the war. The M3 and its variants were produced by many manufacturers including Diamond T, White Motor Company and Autocar and were designed for a wide variety of uses, such as a self-propelled anti-aircraft weapon or self-propelled artillery. Although initially unpopular due to its lack of significant armor or a roof to protect the crew from shrapnel, it was used by most of the Allies during the war.
In the Cold War era, the vehicle was used by a variety of state and non-state operators in conflicts in South America, the Middle East, Africa, and Asia, remaining in service until as late as the mid-1990s. In Mexico they are still in use as of 2019.

Specifications

The M3 half-track was long, wide, high and weighed. The wheelbase was long. The suspension consists of a leaf spring for the two front wheels, while the rear treads had vertical volute springs. With a fuel capacity of 60 US gallons, the M3 could carry its crew and a squad of 12 soldiers before refueling, while protecting them from small arms with light armor. The vehicle was powered by a White 160AX, 386 in3, 6-cylinder gasoline engine, giving the vehicle a power-to-weight ratio of 15.8 hp/ton.

Design

The design, which used many commercial components to improve reliability and the rate of production, was standardized in 1940 and built by the Autocar Company, Diamond T Motor Company, and the White Motor Company. With a White 160AX engine, the M3 was driven through a manual constant-mesh transmission with four forward and one reverse gear, as well as a two-speed transfer case. The front suspension uses leaf springs, while the tracks use vertical volute springs. Braking was hydraulic assisted while steering was manual. Onboard electronics run on a 12-volt system. The vehicle uses two tracks made of molded rubber over steel cabling with metal track guides.
Infantry rifles were held in brackets behind the seats while ammunition and rations were generally stored underneath. In 1942, the vehicles were fitted with a small rack for land mines on the outside of the hull, just above the tracks. In combat, many squads found it necessary to stow additional rations, rucksacks and other crew stowage on the outside of the vehicle. Luggage racks were often added in the field, and later vehicles were fitted with rear-mounted racks for this purpose.
Early vehicles had a pintle mount, just behind the front seats, that mounted a.50-caliber M2 Browning machine gun. The later M3A1 adopted a raised, armored pulpit mount for the.50-caliber and additional.30-caliber machine guns mounted along the sides of the passenger compartment. Many M3s were later converted to M3A1s. The body was fully armored, with an adjustable armored shutter for the engine radiator and a bulletproof windscreen.

Development

The development of an armored half-track began with ordnance directive OCM 14188 to convert a M3 Scout Car into a half-track. The prototype was built at Rock Island Arsenal with help from White Motor Company and was designated the T7. It had the same chassis and engine as the M3, but had larger front wheels and a shorter front clip. The armor consisted of 1/4 inch of hardened armor plate and it was armed with two M1919 machine guns and one M2 Browning machine gun operated by a crew of eight. Tests at Aberdeen Proving Ground in 1938 demonstrated unsatisfactory performance due to the front-wheel drive. The T7 was converted back into a scout car and returned to the Army.
Throughout 1939 and 1940, the M2 half-track car was prototyped and developed by the Army at Aberdeen Proving Grounds. The M3 was developed as a larger version of the M2 equipped with two M1919 machine guns and an M2 Browning machine gun for combat usage. The M3 also added a rear door and five additional seats in the rear. The M3 was tested at Aberdeen Proving Grounds in the summer of 1941 and was accepted into service soon after.

Service history

In US service, it was intended that the M3 would be issued to armored infantry regiments. It was also quickly put into action with the Provisional Tank Group when the Japanese Army began their invasion of the Philippines. At first, there were multiple complaints due to several mechanical difficulties. These were rectified by the Ordnance Department after receiving field reports from the Philippines. The M3s first use in its intended role was during Operation Torch. Each armored division had 433 M2s or M3s, 200 in the armored regiments and 233 in the armored infantry regiment.
The half-tracks were initially unpopular and dubbed "Purple Heart boxes" by American troops. The chief complaints centered on the complete lack of overhead protection from Air burst artillery shells and that the armor was inadequate against machine gun fire. Omar Bradley quoted in his report about half-tracks that it was "a competent and dependable contrivance. Its bad name resulted from the inexperience of our troops who attempted to use it for too many things". Another major issue with the M3 was its fixed rear idler, which often broke on rough terrain. Commanders in North Africa bought parts to build spring-loaded rear idlers that could handle the rough terrain, which the Ordnance Department then approved as an official fix. In 1943, the M3 served in Sicily and Italy and received positive reports of it in action. It operated in Operation Overlord and served in Europe for the remainder of the war.
Total production of the M3 and its variants ran to nearly 54,000 vehicles. To supply the Allied nations, International Harvester produced several thousand of a very similar vehicle, the M5 half-track, for Lend-Lease.

Variants

Armored personnel carriers

Various attempts were made to mate the 40 mm Bofors L/50 gun to the M3 chassis. In most cases the weapon's recoil was too severe or the mounting too heavy, and the attempts were finally stopped with the adoption of the M19 MGMC on the M24 light tank chassis.