M75 (APC)

Infobox Weapon
name=M75


caption=An M75 APC at the Brussels army museum.
origin=United States
type=Armoured personnel carrier
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number=1,729
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weight=42,000 lb (18,800 kg)
length=204 inches (5.2 m)
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width=112 inches (2.5 m)
height=108.5 inches (2.8 m)
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vehicle_range=115 miles (185 km)
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speed=44 mph (71 km/h)
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The M75 is a U.S. armoured personnel carrier that was produced between December 1952 and February 1954, and saw service in the Korean War. It was replaced in U.S. service by the smaller, cheaper, amphibious M59. The M75's were given as military aid to Belgium where they were used until the early 1980s. 1,729 M75's were built before production was halted.

Development

Towards the end of World War II a tracked, fully enclosed armoured personnel carrier was developed under the designation M44 (T16) based on the M18 tank destroyer. The M44 was extremely large (51,000 lb combat weight), carrying 24 infantry as well as a driver, bow gunner and vehicle commander. It was evaluated at Fort Knox and Aberdeen Proving Ground after the end of the war but ultimately the army rejected the M44 as being too large, at the time their tactical doctrine required infantry squads of ten men. As a result only a handful of M44s were built, seeing service in a number of auxiliary roles.

On 21 September 1945 a set of requirements were laid down for a squad sized armored personnel carrier, based on the chassis of the T43 cargo carrier. On 26 September 1946 the development of the armoured utility vehicle T18 was approved with the International Harvester Corporation (IHC) contracted to produce four prototypes.

The original mockup featured two remote controlled .50 calibre machine guns, that could be aimed remotely by either the commander or either of two gunners, having a total crew of 14.

The first prototype T18 dropped one the assistant driver but retained the remote controlled machine guns. The T18E1 pilot was unarmed and had a high cupola for the commander, this is sometimes referred to a pilot number 4. The T18E2 replaced the commanders cuppola with a T122 machine gun mount that could be fitted with a .30 or .50 calibre machine gun.

Though the original T18E1 prototype was unarmed, the high cuppola was replaced with a variety of machine gun mounts, before the M13 cupola with a .50 calibre machine gun was evaluated.

The prototypes were originally powered by a six cylinder AO-895-2 Continental air cooled engine, which exhausted through the hull side grills. This was later replaced with the AO-895-4, which exhausted through a pipe mounted horizontally across the front of the vehicle.

After acceptance testing the T18E1 was ordered into production in 1952 as the M75. Although the vehicle was developed by the IHC, an order for 1,000 were placed with IHC and for 730 at the Food Machinery and Chemical Corporation. Numerous changes were made during the production run to reduce cost and complexity. The number of shock absorbers was halved from four per side to two, and an auxiliary generator/heater was deleted. The two 75 gallon rubber fuel tanks were replaced by a single 150 gallon metal one.

The M75 shared many chassis/suspension components with the M41 light tank, also powered by a Continental air-cooled engine. It had a cross-drive transmission (permitting pivoting, etc.) but was steered through two vertical handles, simulating the laterals of earlier vehicles controlled by track clutching/breaking.

The approximate cost of the vehicle was 72,000 US dollars which contributed to the early halting of production. The high profile (height) of the vehicle was also a negative factor. Additionally the engine air cooling vents were considered to be vulnerable to small arms fire. However, the reliability of its drive system was far superior to that of its M59 replacement.

Description

The M75 has a welded steel hull, which varies in thickness from convert|1|in|cm|1|abbr=on|lk=on to convert|1.5|in|cm|1|abbr=on inch with a line of sight thickness on the front hull of between convert|1.6|in|cm|0|abbr=on and convert|2|in|cm|0|abbr=on. Fully loaded, the vehicle weighed approximately convert|42000|lb|kg|0|abbr=on|lk=on.

The M75 has an almost identical layout to later U.S. armoured personnel carriers: the driver sits in the front left of the hull, with the air-cooled six cylinder horizontally opposed Continental AO-895-4 petrol engine to his right. The driver is provided with an M19 infra-red night vision periscope in later models and four M17 periscopes. Behind the driver and engine in the center of the vehicle sits the commander who is provided with six vision blocks around his hatch. The commander has a cupola which was normally fitted with an M2 machine gun, for which 1,800 rounds were carried in the vehicle. with the infantry behind him in a large compartment. Additionally an M20 Super Bazooka was carried along with 10 rockets, and a M3 submachine gun with 180 rounds of ammunition.

The engine developed a maximum of around convert|295|hp|kW|0|lk=on at 2,660 rpm giving the vehicle a top speed of convert|44|mph|km/h|0|abbr=on|lk=on. The vehicle carried convert|150|usgal|L|0|lk=on of petrol, giving it a road range of around convert|115|mi|km|0|lk=on. It has five road wheels and three return rollers on each side.

pecifications

* Fording depth: 48 inches (1.2 m) / 76 inches with fording kit
* Vertical obstacle: 18 inches
* Trench: 66 inches
* Gradient: 60 percent
* Suspension: Torsion bar

References

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