Medium Tank M4A1/ Sherman II

The Medium Tank M4A1/ Sherman II was the second version of the Medium Tank M4 to be standardized but the first to enter production. It combined a cast upper hull and a Wright radial engine, and was used by US and UK forces.

The M4 was developed to replace the obsolete Medium Tank M2 and the interim Medium Tank M3, which carried its main 75mm gun in the right of the superstructure. Work on the prototype Medium Tank T6, which had a cast hull, was completed by September 1941, and the type was accepted for production. On 11 December 1941 two versions were given designations - the M4 with a welded hull and the M4A1 with a cast hull.

M4A1 Sherman in Luxemburg
M4A1 Sherman
in Luxemburg

The M4A1 entered production at the Lima Locomotive Works in February 1942, on a British contract. The first machine to be completed had the same cast hull as the T6, with holes for the side doors, and was given a British War Department number, although it was used for tests in the US. The second machine had the new M4A1 cast upper hull, with the side doors eliminated, and was shipped to Britain. Production of the M4A1 ended at Lima in September 1943

The Pressed Steel Car Company began production of the M4A1 in March 1942, and completed its last M4A1 in December 1943.

Finally the Pacific Car and Foundry Company produced a production pilot in May 1942 before beginning full production. Production ended in November 1943.

In total the three factories built 6,281 M4A1s armed with the 75mm gun. 

Between August 1944 and May 1945 2,259 early M4A1s were refurbished, bringing them close to the most modern specifications (see below for details of changes made during the production run). These tanks were then sent to the combat zone.

The Pressed Steel Car Company then began production of the M4A1(76), and completed 3,426 of this model between January 1944 and the end of the war.

The M4A1 used a cast upper hull, with the side doors of the T6 removed to strengthen the hull. On the T6 the driver had his own roof hatch but the assistance driver was meant to use the side doors, so on the M4A1 a second roof hatch was installed. Both roof hatches had periscopes. Periscopes were also added to the split hatch on the turret (for the commander) and on the turret roof (for the loader).

It was powered by the Wright-Continental R975 air cooled radial engine, and had the same engine deck as the M4. This included a flat armour plate mounted 3in above the rear deck to protect the engine air intake (just behind the turret).

The first tanks to be completed had two fixed bow machine guns, a feature that had been eliminated from the official design in favour of a single ball mounted gun. They also used the original Vertical Volute Spring Suspension bogies from the M3, with the return roller directly above the centre of the bogie. The M4A1 used a welded lower hull, and early production vehicles had the three piece differential covering at the front.

The turret had a powered traverse mechanism. The Oilgear hydraulic system was preferred, but Logansport hydraulic and Westinghouse electric systems were also used in order to speed up production.

Production tanks had a 2in thick rotor shield in front of the 75mm mount, designed to prevent small arms fire from damaged the rotor and jamming it in place (a similar feature was added on many M3s). As on the M3 extra ventilation was needed, and three armoured ventilators were installed. One was mounted on the turret roof, one on the top of the right sponson just behind the turret and one on the front of the right sponson. This third ventilator couldn't be used on command tanks, as the space was needed for the antenna for the SCR 506 radio.

During the production run of the M4A1 a series of changes were introduced. The two fixed bow machine guns were replaced with a single machine gun in a ball mount. An anti-aircraft gun could be mounted on a rotating ring on the turret hatch. At first this was a .50in gun, but between September 1942 and April 1943 a .30in gun was used instead. Late production vehicles used the one piece differential cover. Heavy duty suspension bogies were introduced in the summer of 1942. These had stronger volute springs, and the return wheel moved from the top of the central structure onto its own arm.

Early production vehicles had a periscope type gun sight, but this could easily be knocked out of alignment, and it was replaced by a telescopic sight mounted to the right of the gun.

Of the 6,281 M1A1s that were built with a 75mm gun, 942 went to the UK, where they served as the Sherman II, and most of the rest were used by the United States.

Stats M4A1 (Early Production)
Production:
Hull Length: 230in
Hull Width: 103in
Height: 108in
Crew: 5
Weight: 66,800lb combat loaded
Engine: Continental R975 C1, 9 cylinder air cooled radial
Hp: 350hp at 2,400rpm
Max Speed: 21mph sustained, 24mph max
Max Range: 120 miles cruising range, roads
Armament: 75mm Gun M3 and 0.30in MG in turret, 0.5in MG in AA mount on turret, 0.3in MG in bow mount

Armour

Armour

Front

Side

Rear

Top

Turret

3.0in

2.0in

2.0in

1.0in

Hull

2.0in

1.5in

1.5in

0.75in

Gun Shield

3.0in

 

 

 

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How to cite this article: Rickard, J (16 September 2016), Medium Tank M4A1/ Sherman II , http://www.historyofwar.org/articles/weapons_medium_tank_M4A1_sherman_II.html

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