type: troop carrier vehicle.
Crew:3 men + 10 fighters.
Armament: a 50 M2 machine gun or a 30 M1919A4
Armor :
minimum 7 mm;
maximum 13mm
Dimensions:
length: 8.17 m;
width: 2.22m;
height 2.26 m.
Weight in combat order: 9 t.
Ground pressure: 0.79 kg/cm2.
Power to weight: 16.5 bhp.
Engine: White 160AX 6 cyl. in-line gasoline engine, developing 147 hp at 3,000 rpm.
Performance:
road speed 72 km/h:
road range: 312 km;
vertical obstacle 0.6 m;
ford 0.8 m;
slope: 60%.
Service time: introduced into the US Army in the summer of 1941. Also employed by France. Great Britain, the Netherlands and the Soviet Union Still in service with the Israel Defense Forces
The rapid transport of the infantry accompanying the armored vehicles, to enable them to enter into action at the same time as them, on vehicles capable of moving over all terrain, was taken into consideration by the Americans in the light of the experiments conducted in Germany by the recently reconstituted Wehrmacht. After a few experimental attempts, the manufacture was launched in 1939 of the M.2 and M.3 half-tracked vehicles, the use of which contributed to giving extreme mobility to the armored units of the Allies. The production of this type of vehicle reached figures allowing an ample endowment of the American troops and their British, French and Soviet allies. In addition, the chassis served as a support for many variants.
After the war, the half-tracks were used in very many
armies. They are still used effectively today, by the Israelis in particular.
In the United States, the first tests of semi-tracked vehicles for troop transport took place in 1939, probably when American experts were informed of the very wide distribution of this type of means within the German forces. It was decided to combine two vehicles already in service, the Scout Car M.3A1 (armored reconnaissance vehicle on 4 x 4 wheels) and the semi-tracked vehicle M.2 (truck equipped by Marmon-Herrington with a rear tracked).
From this fusion was born the Car half-track M.2, prototype of the half-tracked troop transports which were to know such diffusion during (and after) the Second World War.
Also in 1939, an elongated model (13 seats instead of 10) was studied and subsequently adopted under the name of M.3.
The order for mass production of the M.2 having been given in the meantime (Sept. 1940), the Autocar company produced 2,992 copies, and White Motor Co. 8,423 others, between 1940 and 1943.
Then came the M.2A1 version, on which was mounted to the right of the driver a firing circular for the 12.7 mm Browning heavy machine gun (the M.45 mounting often nicknamed "Pulpit-Pu clown"). From October 1943 to March 1944, 1,643 semi-tracks of this type were produced. And at the same time the order had been placed for the neighboring model
M.3 of which Autocar and Diamond T Motor Car Co. produced 12,499 units. These vehicles spawned 70 sub-versions, the most interesting of which are described below.
The technique
The chassis of these various half-tracks differed from that of a normal vehicle with two driving axles in that the rear axle was moved forward as far as possible to constitute the driving end of the tracked train. The armored body was fixed on the chassis. It consisted of a frame to which protective panels of hardened sheet metal were bolted by round-head screws and self-tightening bolts. All these panels were 6 mm thick, only the one that replaced the windscreen and the sliding panels of the side doors, was 12.7 mm thick. The floor plates were made of aluminum or non-slip steel and bolted to the frame or on hinges for those which served as inspection hatches. The armor protected the occupants of the vehicle from rifle and
machine gun bullets and shrapnel. The top section of each side panel could be folded down around hinges and held in the up position by a vertical latch attached to the body of the panel. The unbreakable glass of the windscreen was divided into two panels and its protective shield, hinged on the upper part, was normally held horizontally by means of three locks. However, before putting it in the "closed" position, the glass panels had to be removed. Firing tapes had been provided in the front and side walls of the front compartment.
The front roller served to prevent the front of the vehicle from sinking into the ground in rough terrain and to facilitate movement in the brush. It consisted of a cylindrical drum equipped with spring dampers.
The engine and the radiator were also protected by steel sheets, the second having four protective flaps that the it could be closed by remote control from the right of the driving position. The hood consisted of two double panels hinged together. To shelter the occupants of the vehicle from the weather, there was a hood supported by three arches. The sapper tools were stowed under the side doors, an ax on the right side, a shovel and a pickaxe on the left. On later models there was a 20 liter nurse on either side of the bonnet.
Inside the M.3 there was room for 13 men, 3 in the driving position and 5 on each side of the body. The two self-sealing tanks, with a capacity of 120 liters each, were mounted laterally just after the driving position. There was also a pivot mount for the 7.62mm machine gun in the front post, behind the center seat, if the vehicle was not equipped with the machine gun "desk", as in the case of the M.3A1 , improved version, produced in more than 2,852 copies between October 1943 and March 1944 by White, Autocar and Diamond T.; some M.3A1s were fitted with a winch instead of the front roller.
The driving controls were of the conventional type. In addition, when the vehicle was equipped - as was generally the case on the latest models - with a 4,530 kg winch, there was a winch clutch lever, a reduction gear and a power take-off.
Note that, for the first production models, the headlights were mounted directly on the mudguards, as they were on the Scout-Car. Subsequently, they were
smaller and placed on the sides of the radiator to improve protection.
The engine was a 6-cylinder White 160 AX, without speed regulator. the recommended speed should therefore not exceed 72 km/h. It could reach 88.5 km/h, but only on a motorable road.
The transmission consisted of a single-plate dry clutch, a 4-speed always-mesh gear box forward gears and one reverse gear, with reducer. The drive shafts were equipped with cardan and telescopic joints. The front axle was reserved for the steering, with semi-axles equipped with homokinetic joints.
The rear axle included 4 rubberized support rollers (diameter of 305 mm, width of 105 mm), integral by suspension joints consisting of spring shock absorbers. Each caterpillar, made of endless steel ribbon covered with rubber and approximately 32 cm wide, ran at its upper part on two metal rollers and remained taut under the effect of a suspended and adjustable tension pulley.
The front tires were initially mounted on off-the-shelf disc wheels, then on military-type wheels, with a rim fixed by 18 bolts.
The brakes were hydraulic , with vacuum brake booster and disc parking brake. The steering wheel was on the left. As armament, the standard M.3A2 had a 12.7 mm M2HB machine gun, two 7.62 caliber model M1919A4 (all Brownings), a 60 mm M9 or M9A1 anti-tank rocket launcher, an MM3 automatic carbine, twelve Garand M.1 rifles, with an endowment of three hundred and thirty 12.7mm cartridges, two thousand 7.62s, six M6 anti-tank rockets, twenty-four Ml mines, forty-eight hand grenades and one hundred and eighty rounds for the automatic rifle.
Derivatives
The first variant, intended mainly for export, was manufactured by International H.C. for the British army, under the name of M.5, or M.5A1 if it was equipped with the "desk". As differences, we noted the International engine of 143 HP instead of 147, the welded body forming a homogeneous shielding, the rounded edges at the rear and the flattened mudguards and no longer enveloping. The axles were of the “banjo” bridge type, under I.H.C. Following these modifications, the mass of the vehicle increased by approximately 560 kg.
From May 1941 to 1945, the United States produced 45,044 half-tracked vehicles, including experimental self-propelled or homologated carriers artillery or mortars, multi-purpose self-propelled, etc., a total of 37,164 transport vehicles and 7,880 semi-tracked self-propelled.
In fact, after having been designed as armored vehicles of transporting personnel and equipment as part of the great armor
dated, the M2/3 soon proved capable of receiving heavy weapons.
The first cannon to have been mounted on an M.3 was the 75 mm M1897/A4 on an M3 mount, an achievement of Major (at the time) Robert J. Icks, one of the greatest specialists in this field. Intended for command units of tank destroyers, it was manufactured in large series from 1941 and engaged in the Philippines where it proved to be a formidable destroyer of Japanese armor.
Another self-propelled project was carried out , with mixed success, by mounting a 75mm mounting piece to the chassis. Quite successful, on the other hand, was the adaptation on half-tracked vehicle of multiple parts of D.C.A.; thus the M.15 armed with a light cannon of 37 mm and two machine guns of 12.7 which was manufactured in 680 specimens; as for the very popular M.16, it was armed with four 12.7 mm tubes on a Maxson carriage. It was the best of all the adaptations of these half-tracked transport vehicles.