Medium Tank T6

The Medium Tank T6 was the prototype for the Medium Tank M4 Sherman, the most important American tank of the Second World War.

The fighting in Western Europe in 1940 made it clear that the new Medium Tank M2, with its 37mm main gun and machine gun turrets, was already obsolete. The US military responded with two related development programmes.

The first was based on the experimental Medium Tank T5E2, which had carried a 75mm Pack Howitzer M1A1 in the right of the main hull. The T5E2 had performed well in tests, and was thus adopted as the basis of the Medium Tank M3/ Lee/ Grant/. The official requirements for the M3 were issued on 13 June 1940, and development proceeded at great speed. The basic design was completed by 1 February 1941, the pilot tank could move under its own power by 13 March and the tank was in production by the end of the summer of 1941, one year after the specification was issued.

The M3 was always seen as an interim design, to fill the gap before a new 75mm turret could be designed. This was the focus of the second development programme. The Armored Force issued the design characteristics of the new tank on 31 August 1940, but work was then largely put on hold while the US design team at Aberdeen worked on the M3. In February 1941, after completing the M3, work then moved onto the M4.

The basic outline of the design was agreed at a meeting at Aberdeen on 18 April 1941. The new tank was to use the lower hull, engine, power train and suspension of the M3. The engine compartment would be enlarged so it could take the upcoming Wright G100 or G200 engines as well as the R975 engine of the M3. The upper hull would be new, and could be cast or welded (the riveted production of the original M3 was abandoned).

The most important difference was in armament. The 75mm gun would be moved from the hull to a new turret. In order to carry the larger gun, the turret ring was increased to 69 inches, and moved onto the centre line of the tank (from its position on the left of the M3). The turret was designed from the start to be able to carry different combinations of guns. Five were originally considered - one 75mm gun and one .30in MG, one 105mm howitzer and one .30in MG, two 37mm guns and one .30in MG, one British 6-pounder and one .30in and finally three .50in MG in an anti-aircraft configuration. Of these the two first would enter production. The 75mm gun version would use a gyrostabilizer for elevation.

The original design for the turret also included a machine gun cupola, similar to the one used on the M3, but this doesn’t appear to have been installed on the prototype, although it did appear on the earlier wooden mock-up.

Work on the prototype Medium Tank T6 was carried out at Aberdeen, and it was completed by 2 September 1941. The T6 used a cast upper hull, with side doors in the sponsons. The T6 was armed with a short 75mm gun M2, which needed two counterweights to operate properly with the elevation gyrostabilizer (designed to work with the longer 75mm gun T8 (M3)). The T6 carried two radios, an SCR 506 voice and code radio in the front right of the hull and an SCR 508 voice radio in the turret bustle. The turret mountings could also take a British Number 19 radio, a sign that the M4 was designed with British use in mind.

The T6 was inspected on 2 September, and the decision was made to eliminate the machine gun cupola from the turret and the side doors. On 5 September the Ordnance Committee recommended that the T6 should be standardised as the Medium Tank M4. This recommendation was approved in October.

Work on production pilots began in November. Right from the start the M4 was to be produced in multiple versions, in order to speed up production. On 11 December 1941 those with welded hulls were given the designation M4 and those with a cast upper hull the designation M4A1. The M4A1 was the first to enter production, probably because of the work done on the similar T6. It was followed into production by the M4A2, which combined the welded hull of the M4 with a General Motors power plant. The M4 was thus the third of the series to enter production.

Stats
Production:
Hull Length: 222in
Hull Width: 107in
Height: 115in
Crew: 5
Weight: 60,058lb
Engine: Wright Continental R975 EC2 9 cylinder air cooled radial engine
Hp: 340hp at 2,400rpm
Max Speed: 21mph sustained, 24mph max
Max Range: 120 miles cruising range, roads
Armament: 75mm Gun M2 and .30in MG in turret, .30in MG in turret cupola, three .30in MG in hull front

Armour

Armour

Front

Side

Rear

Top/ Bottom

Turret

3.0in

2.0in

2.0in

1.0in

Superstructure

 

 

 

 

Hull

2.0in

1.5in

1.5in

1.0in

Gun shield

3.0in

 

 

 

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How to cite this article: Rickard, J (1 September 2016), Medium Tank T6 , http://www.historyofwar.org/articles/weapons_medium_tank_T6.html

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