WW2 american Halftrack transport car M2 and M3, derived from the M3 Scout Car. 
TANKS ENCYCLOPEDIA
The online tank museum

 M2/M3 Half Track Car

Armored transport (1940-45)
USA - about 56,500 built

Genesis: The T7 and Kégresse track systems

French car-maker Citröen had already produced half-track cars, developed by engineer Adolphe Kégresse. They were modified Rolls-Royce and Panhard derivatives for the Tsar, made just before WW1. Citröen made a famous worldwide trip, the "Paris-Pékin", also known as the "Yellow Cruise", using such half-track cars. Between 1921 and 1937, the French army adopted them as well, as did the Polish army. Other countries built them under licence. The US Army bought several Citröen-Kégresse vehicles for evaluation in the late twenties, and developed their own system, still retaining the original flexible belt track. The first prototype, the T7, was the forerunner of a famous lineage, spanning 70 versions and a production of 41,000 vehicles during WW2 alone. The T7 was ordered by the US Ordnance department, which was looking for a prime mover and reconnaissance vehicle. It was developed by the White company in order to extensively test and improve the Kégresse track system. They mounted it on a custom chassis, with the body and parts from their M3 Scout Car, already in production. The T9 Half-Track truck, another prototype which was deemed too heavy, gave its Timken rear bogie assembly to the T7, and the lighter vehicle appeared successful on trials. But, being under-powered, the T7 was equipped with a more powerful car engine, eventually giving the T14 final prototype, which was the blueprint for the M2 Half Track Car.

Characteristics: A derivative of the M3 Scout Car

The M3 Scout Car was another successful product of the White Motor Company of Cleveland. It was devised as the main armored scout car of the US Army, after a request from the US Army Ordnance department. Its main feature was a four wheel drive, four-speed manual constant-mesh (non-synchromesh) transmission. Its hull was armored (mostly on the front), and it had vacuum-assisted power brakes. Assembly was made by bolting. After an initial pre-series of 64 machines in 1939 for the 7th Cavalry Brigade, an improved M3A1 version was designed for mass production. Nearly 21,000 were built until 1944. It gave many elements to the M2 Half Track, giving a strong family tree resemblance to the three armored vehicles (along with the M3 Half-Track) It also helped standardization, and thus benefiting cheap production and easy maintenance. The entire hull, brakes, transmission, forward axle and wheels, machine guns fixations, and even the bumper unditching roller, were copied to the M2. Although longer, many believed that the M2 was basically a Half Track version of the M3 Scout Car. Ground clearance was 11.2 inches (28.4 cm). The White 160AX was a 6 cylinder, 4 cycle, in-line gasoline engine, with a net horsepower of 147@3000 rpm, and a 325 ft*lb@1200rpm torque. Standard fuel capacity of 60 gallons (230 l). Max speed on road was 45 mph (72 km/h). Turning diameter was 18 m (59 ft), max vertical obstacle 30 cm (1 ft) and fording depth 81 cm (2.67 ft). The front axle had semi-elliptic longitudinal leaf springs, with steel ventilated discs. The rear one had vertical volute spring, one per bogie. The rear suspension had 4 roadwheels mounted on the boogie, with 18-tooth front drive sprockets, and adjustable fixed idlers at the rear. The track was of the center guide band type, 12 inches (30.4 cm) wide, with a 4 inch (10 cm) pitch, 58 pitches in all. The total ground contact length was 46.75 inches (1.18 meters). The front wheels could be engaged for cross-country travel.

Main production and M2A1

In 1941, the first units were equipped with this armored transport, some being based in the Philippines. 11,415 M2 Half-Tracks were produced by White motor co. and Autocar Co., a few of them being improved M2A1s. Throughout the war many variants appeared, some 2085 such M2-based vehicles being produced. They all had the "short hull" in common, along with relatively weak armor on the sides, stronger rolled face-hardened steel plates at the front, folded protective panels with loopholes for the drivers protection around the driving compartment, with ammunition stowage accessible from the inside or through external side panels. The headlights were mounted on the fenders, but this proved fatal on gun-equipped versions. There was a roomy open trolley equipped with retractable seats, munitions cases, spare parts. Two types of machines guns could be fitted, a heavy Browning 50 cal. M2HB (12.7 mm) and up to three cal.30 M1919 A4 (7.62 mm) machine-guns, with flexible skate mounts. These were later replaced with pintle mounts. The main cal.50 (12.7 mm) was mounted forward, just over the assistant driver's seat. It had an anti-aircraft and anti-personal 360° M49 ring mount. This provided the M2 with excellent firepower. Their main problem was the weakness of the immovable trolley upper side panels, which were not always able to stop MG 34 and MG 42 bullets. Provision was 700 rounds for the cal.50 (12.7 mm), and 7750 for the others. Depending on the version, additional storage racks were added to carry extra bogie wheels, iron cables or extra ammunition and fuel cases. Nearly all, from the beginning, included the frontal unditching roller, shovel and pickaxe, and fixations for fuel cans. A towing device at the rear allowed them to tow the standard M2/M3 howitzer and other light guns. Later vehicles had smaller, detachable headlights on either side of the hood, and optional anti-ditching roller or a 10,000lb (4500 kg) capacity winch. The M2A1 differed by the machine-gun mounts, and 1643 machines were built, with another 1266 later converted.

Versions of the M2 Half Track

With eleven main versions and many sub-versions, the M2 was a testbed for many configurations, despite not being armored enough for front-line operations. These changes concerned, first and foremost, adding infantry support armament to the vehicle, added firepower, and adaptations for specific tasks. The first M2 model was equipped with a single, forward cal.30 (7.62 mm) machine-gun. As it was soon found insufficient, a forward M2HB cal.50 (12.7 mm) on a skate rail mount, derived from the M32 truck, quickly became the trademark of the M2. Other sockets for skate mounts were placed, for up to three additional cal.30 (7.62 mm) machine-guns. The M2A1 introduced the M49 mount for the main caliber and pintle mounts for the secondary machine-guns. The M9 (M2E5) was the Lend-Lease version produced by the Harverster Co., with a longer hull and rear access doors, and somewhat different internal configuration. The M9A1 was a sub-version introducing the improved gun mounts of the M2A1. There were also two self-propelled artillery versions, the mortar one being the M4 and M4A1s, with a 81 mm (3.2 in) M1 mortar fixed inside the crew compartment. The M2 w/ M3 37 mm (1.46 in) was equipped an antitank gun fitted with a protective shield, forward mounted. AA versions included the T1E1 to T1E3 prototypes, with Bendix and Maxon mounts, or a Martin turret and partial hard-top. The T28 CGMC had a single M1A2 AA 37 mm (1.46 in) autocannon, which was thoroughly tested and gave birth to the M3-based T28E1. There was also the T10, featuring a Hispano-Suiza HS.404 20 mm (0.79 in) cannon, which was later used for the T10A1 on the M3 chassis. All these AA experimental versions lead to the successful M3 AA conversions.

M3 Half Track

The M2 was initially conceived as an artillery tractor, with only space for the gun crew. Thus the M3 was created in late 1940, with a longer body, in order to accommodate a full platoon of thirteen riflemen and their equipment. The access was performed through the back door, and the galley part of the hull didn't incorporate an ammunition hold. It was simplified for mass production, but the wheelbase and other general characteristics remains unchanged. The M3 was produced by the Autocar Company, Diamond T Motor Company and the White Company until the end of the war. It was, at first, fitted with the reliable White 160 Ax 386 cu in (3660 cc) engine, a gasoline six cylinder with a compression ratio of 6:3:1 and a power to weight ratio of 15.8 hp/ton. But a more powerful array of IHC engines became available, and many later versions were remotorized until the end of the war. First gun mount was a pintle for a cal.50 (12.7 mm) M2 heavy machine gun, and two other pintle mounts on the inner hull sides. This early arrangement was replaced by the "pulpit mount" M49 for the cal.50 (12.7 mm), as well an an extra aerial pintle mount for a third cal.30 (7.62 mm), and vehicles thus armed were named M3A1. Many complaints rose about the lack of protection offered by the armored panels, as these half-tracks were infamously dubbed "Purple Heart Boxes" (this decoration was offered to all servicemen wounded by the enemy, often posthumously). It was apparent that machine gun fire could pierce its armor, and the lack of roof protection was critical in the face of shrapnell and air-burst shells. Over 41,000 M3s were built, plus 2000 M5s produced by International Harverster Co for Lend-Lease, with a IHC RED 450B engine, modified drive train, electrical and fuel systems.

M3 variants

Like the M2, the M3 was adapted for many purposes. Besides the regular M3 and M3A1, and the late (never produced) M3A2, there were two specific variants for Lend-Lease. The M5 was provided to Great Britain, USSR, Canada and France, with sub-versions M5A1, M9 and M9A1 differing by some equipment, fittings (inspired by the M2), radio access and rear doors. All were regular troop transports. The two main specific variants of the war were gun carriers and anti-aircraft models.

The self propelled guns variants were the T12/M3 and T12/M3A1 HMC, equipped with the M1897 A5 75 mm (2.95 in) howitzer and its gun carriage, with a special-purpose shield in later versions. This gun stock was exhausted and new variants appeared, the T12 GMC equipped with a 75 mm (2..95 in) long barrel or 105 mm (4.13 in) for the USMC,. The T48 and T30 GMC were built for the US army, equipped with, respectively, the 57 mm (2.24 in) M1 gun (US adaptation of the British QF 6-pounder antitank gun) and 75 mm (2.95 in) M1A1 howitzer. The T19 was equipped with the M2A1 105 mm (4.13 in) howitzer. The T19 also had mortar version, equipped with the 81 mm (3.19 in), also known as the M21 MMC.

Anti-aircraft versions were highly successful, developed upon M2 special versions and experiments. The M13 MGMC was the first one, with the M14 sub-version, fitted with a Maxson M33 double mount for two cal.50 (12.7 mm) M2HBs and 5000 rounds in store, with removable side panels. The M14 was based on the M5 chassis, for Lend-Lease, and was provided to Britain. The M16 MGMC was probably the best known and most prolific, with its new Maxson quadmount M45D, sporting four modified 50 caliber (12.7 mm) M2HB machine-guns. The M16A1 had fixed armored panels and the M16A2 had minor modifications and the M45F improved quadmount. The M17 was based on the M5, and exclusively provided to Soviet Union. The T28E1 was a special purpose version equipped with a single 37 mm (1.46 in) cannon M1A2, assisted by two cal.30 (7.62 mm) M2WC machine-guns. Its sub-versions, the M15 and M15A1, had minor modifications. There were also several prototypes fitted with the 40 mm (1.57 in) Bofors canon, but the recoil was so strong that only one was built. The Australian M15 "special" was the only Bofors version successful enough to see mass conversions. All were used in the South Pacific.

The M2 and M3 in combat

The M2 was adopted by the US Army and Marines, and was found in all theaters of war, North Africa, Europe and the Pacific. It proved reliable and versatile, and was fielded by British and Commonweatlh forces under Lend-Lease, as well as by many reconstructed Allied forces (Free French, Polish, etc.). The International Harvester Company made an additional 3500 M9s (an export version of the M2), from which 800 (along with some M2s) were allocated to the Soviet forces. At the end of the war, many surplus Lend-Lease models were sold to South American countries. Some retained their models, with many modifications, until 2009. In all, the M2 was known to have been used by twenty countries, including Czechoslovakia, Chile, France, Greece, Portugal, Brazil, Poland, Israel, Mexico, Nicaragua, Belgium, Netherlands, Cambodia, South Vietnam, Laos, Argentina, and Lebanon. Israel was given many half-tracks and greatly modified them, spanning the Mk.A to D, culminating with the TCM-20,the last modified version. They are still in service today.
Specs.

M2

M3

Dimensions 5.96 x 2.20 x 2.26 m (19.55x7.22x7.41 ft) 6.18 x 2.22 x 2.26 m (20.27x7.28x7.41 ft)
Total weight, battle ready 9 tons 9.3 tons
Crew 2+7 passengers 3+10 passengers
Propulsion White 160 AX petrol, 147 bhp White 160AX/IHC RED 450, 147/160 bhp
Speed 40 mph (63 km/h) road
25 mph (43 km/h) off-road
45 mph (72 km/h) road
28 mph (47 km/h) off-road
Range 320 km (at cruise speed -50 km/h) 382 km (175 mi)
Armament Main Browning M2 cal.50
Secondary 2 cal.30 M1919
Main: Browning M2 cal.50
Secondary 2 cal.30 M1919
Armor From 6 to 12 mm (0.24-0.47 in) From 6 to 12 mm (0.24-0.47 in)
Total production 13,500 43,000
M2
A rare picture of a M2 Half-Track of the early production, somewhere in North Africa.



Links
The M2 Half-Track on Wikipedia
General characteristics and some pictures
Interesting gallery of many M2 and M3 variants
Half Track M2 early

Pre-series M2 with a single cal.30 (7.62 mm) machine-gun on a central pedestal mount. This was the original gun tractor, with just enough room for the gun crew and large ammunition holds. These were used primarily for carrying M1927 pack howitzers to the battlefield. Here is a model used by the USMC in the Philippines, December 1941.

Half Track M2

A M2 with the original skate mount in Algeria, November 1942.

Half Track M2A1

M2A1 with the M48 gun mount and cal.30 (7.62 mm) pintle mounts. France, June 1944.

Half Track M3 italy 1944

Early production M3 with canvas, Italy, 1944.

M5 of the 8th army

A British M5 (the Lend-Lease version built by International Harvester) of the VIIIth Army, Tunisia, January 1943.

FFF M5

Half Track M5 of the Free French First Army, southern France, August 1944.

M3 75 mm HMC

M3 75 mm (2.95 in) HMC equipped with the famous "pack howitzer", Palermo, Sicily, 1944. M3 T12 75 mm GMC

The T12 was the main gun motor carriage derivative of the M3, equipped with a 75 mm (2.95 in) or 105 mm (4.13 in) gun, mostly used by the USMC. Initially T1s2 were equipped with M1897A4 75 mm (2.95 in) guns, an American version of the French famous "canon de 75". When the stocks were exhausted, they turned to more modern guns. Over 2200 GMCs were built prior to April 1943, but only 842 seem to have seen service. The M1897 had an indirect fire range of 9,200 yds (8,400 m), and provision was 59 rounds, either AP M72 (Armor Piercing), APC M61 (Armor Piercing Capped) or the high-explosive antipersonal HE M48. This illustration depicts a 1st US Army GMC stationed in Sicily, 1943.

M3 T12 75 mm GMC

M3 75 mm (2.95 in) GMC in North Africa, US 1st Division, Tunisia, June 1943. The medium velocity of this gun made it unsuitable against most Panzers in 1943. Its AP projectiles were able to pierce only 7.1 to 8.1 mm of armor at 500 yd (460 m). Most of them were used for artillery support. GMCs were also used by the USMC in the Pacific theater, with better success against Japanese tanks. They saw action at Peleliu, Tarawa, Saipan and Okinawa, were they replaced tanks in infantry support.

M3 T12 75 mm GMC

T12 GMC in British service, Eight Army, Tunisia, May 1943.

M3 47 mm GMC

Captured T48 GMC, equipped with the M1 57 mm (2.24 in) antitank gun. It was an American-built version of the Ordinance QF 6-pounder of the British army, used throughout the war.

M3 T48 57 mm GMC

The T48 GMC was a tank hunter, one of the most successful conversions of the M3 Half Track. It was put in production in December 1942, and 962 saw service, while 281 M3A1s were also converted. Each of them was fitted with the high velocity M1 57 mm (2.24 in) antitank gun, with a provision of 99 AT rounds and 22 HEs.

M3 T48 GMC

A T48 GMC in service with Patton's army, Operation Cobra, Normandy, July 1944.

T19 HMC

A regular T19 Howitzer Motor Carriage, based on the M3 chassis, and equipped in a very similar fashion that the former 75 mm (2.95 in) HMC it just replaced. With its long barrel and heavier high explosive shells, it was well suited to add firepower where it was needed. The T19 105 mm (4.13 in) HMC was not a high production vehicle, around 400 were operated in all. But the punishing fire of the howitzer, mounted in the most cost-effective solution yet, made a potent combination.

T21E1 MMC

The M4 MMC was a new concept, entirely refurbished to operate a single regular ordinance 81 mm (3.19 in) mortar. It was accepted in service in October 1940 and 572 were built. Later on, the evolved version came, as the M4A1, which allowed the mortar to fire from the vehicle. It was put in production in December 1942 and 600 were built. They were respectively based on the M2 and M2A1, but then the Ordnance Department decided to exploit the M3 chassis, which came with the M21. The mortar was now forward firing, with a reinforced basis which allowed wide angle fire. But, moreover, there was now a defensive cal.50 (12.7 mm) placed at the rear. Only 110 were built, in early 1944. The T21E1 was an experimental new version. It was superseded by a 107 mm (4.21 in) MMC version.

M13 MGMC

The M13 (and subversion M14) were the first successful AA adaptations of the M3 Half Track, using the Maxson M33 twin mount, operating two M2HB cal.50 (12.7 mm) heavy machine guns, with very good results against low-flying aircraft. Side panels were foldable, to allow a better arc of fire. All the internal compartment was refurbished. They were accepted in January 1943, and 1103 half-tracks were built as M13s, and later, 628 converted into quad-mount M16s.

M16 MGMC

The "quad-mount" or "quad 50" version, is probably the best-known and most produced of these AA variants based on the M3. Based on a new M50 mounting, it had excellent capabilities against low-flying aircraft, and quickly gained the nicknames of "meat chopper" and "Krautmower". This mount allowed fast moving, high rate of fire of the highly reliable 50 cal (12.7 mm) heavy machine guns, most of the time with the new side panels folded. It was accepted in service in May 1943 and no less than 2877 were built, plus 628 converted from M13 stocks, and 109 from twin 20 mm (0.79 in) GMCs. They served in Tunisia, Italy, France and Germany, but also in the Pacific.
ALL TANKS OF THE MONTH
April tank of the month: The T34/76 April 2012
May tank of the month: The M3  Halftrack May 2012
June tank of the month: The Panzer III June 2012
July tank of the month: The Cruiser VI Crusader July 2012
August tank of the month: The Char B1 bis August 2012
September tank of the month: The T26 September 2012
April tank of the month: The M3 Lee/Grant October 2012
November tank of the month: The Panzer IV November 2012
December tank of the month: The Mathilda infantry tank December 2012
January tank of the month: The Type 97 Chi Ha January 2013
February tank of the month: The Russian KV-1 February 2013
March tank of the month: The M4 Sherman March 2013
April 2013 tank of the month: The Merkava MBT April 2013
Sd.Kfz.250  Hanomag May 2013
June tank of the month: The Panzer III June 2013
July tank of the month: The T34/85 July 2013
August tank of the month: M4 Sherman Part 2 August 2013
September tank of the month: The Panther September 2013
October tank of the month: The Renault FT October 2013
November tank of the month: The Churchill November 2013
December tank of the month: The IS-2 December 2013
Chitsmas tank of the month: The Tiger January 2014
February tank of the month: The February 2014
March tank of the month: The AMX-13 March 2014
December tank of the month: The Centurion April 2014
May tank of the month: The T54/55 May 2014
June tank of the month: The Leopard I June 2014
July tank of the month: The M48 Patton July 2014
August tank of the month: The T-72 August 2014
September tank of the month: The AMX-30 September 2014
October tank of the month: The Chieftain MBT October 2014
November tank of the month: The M60 Patton November 2014
December tank of the month: The T-64 December 2014
January tank of the month: The M1 Abrams January 2015
February tank of the month: The STUG-III February 2015
March tank of the month: The AMX-56 Leclerc March 2015
April Fish: The Asad Babil MBT April Fish
April tank of the month: Chinese Type 96 PLA MBT April 2015
May tank of the month: The Cruiser VII Cromwell May 2015
June tank of the month: The Leopard 2 - When the Leopard 1 was out in 1965, it was praised already as the best MBT on the continent. But with the growing soviet threat and avatars of the costly MBT-70 project, West Germany decided to embark on a new generation MBT program armed with a 120 mm and brand new armour package. The Leopard 2A4 was once more adopted by nearly all Europe and beyond. Later KMW inaugurated the up-armoured 2A5, then the up-gunned 2A6, comforting the position of the Leopard 2 as one of the world's leading MBT. June 2015
July tank of the month: The M113. July 2015