Medium Tank M3A3

The Medium Tank M3A3 was the main production version of the M3 to use a welded hull in place of the original riveted hull.

Work on a welded hull began with the successful production of a welded turret. This was followed by a welded hull, which was combined with a cast turret to produce the M3A2. Other than the welded hull this was similar to early M3s, with side doors on the hull and a Wright Continental engine. The M3A2 entered production at the Baldwin Locomotive Works, but only twelve were built in January-March 1942 before work moved onto the M3A3.

The biggest potential bottleneck in tank production was the engines. The M3, M3A1 and M3A2 all used the Wright Continental R975 air cooled radial engine, which was also in heavy demand in the aircraft industry. Several companies were asked to produce alternative engines, amongst them General Motors. They responded with the Model 6046 12-cylinder liquid cooled engine. This was made from two GM 6-71 six cylinder diesel truck engines, mounted on opposite sides of the new engine. Each engine retained its own clutch, so the tank could be driven on one engine if required. The power from the two engines fed a collector gear, which was then linked to the normal M3 transmission. The new engine was rated at 375hp at 2,100rpm, making it more powerful than the Wright Continental engine.

The new engine was also larger than the radial engine, giving the M3A3 (and later GM powered Shermans) their main identification feature. The rear armour was extended down to the level of the top of the tracks, and the rear plate sloped outwards by 10 degrees. Just below was a deflector plate, which was intended to divert the exhaust gases away from the ground and reduce dust.

The new engine was tested in Medium Tank M3 No.28, and the new engine was approved for use in October 1941. The new engine was more fuel efficient than the radial engine, so the amount of fuel carried could be reduced without affecting range. The M3A3 was also noticeably faster than the M3.

At first the designation M3A3 was allocated to all M3s powered by the GM engine, including those with welded and riveted hulls. This was than changed so that the M3A3 covered tanks with the GM engine and welded hulls, while GM powered tanks with riveted hulls became the M3A5.

The two diesel powered models were produced at the Baldwin Locomotive Works between January 1942 and December 1942. During that period 322 M3A3s and 591 M3A5s were built. During the production run the side doors were welded shut to increase strength and three extra ventilators were installed (the same changes were made to the M3 and M3A1).  

Production: 322
Hull Length: 222in with M2 gun, 241in with M3 gun
Hull Width: 107in
Height: 123in
Crew: 6 or 7
Weight: 63,000lb combat loaded
Engine: General Motors 6046 12 cylinder twin inline liquid cooled
Hp: 375hp at 2,100rpm
Max Speed: 25mph sustained, 30mph max
Max Range: 150 miles cruising range, roads
Armament: 75mm Gun M2 or M3 in front right of hull, 37mm Gun M5 or M6 in turret; three .30in machine guns - one in turret cupola, one coaxial in turret, one in hull front






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How to cite this article: Rickard, J (24 June 2016), Medium Tank M3A3 ,

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