T20 medium tank

Series of armored fighting vehicles designed by the United States

The Medium Tank T20, Medium Tank T22 and Medium Tank T23 were prototype medium tanks, developed by the United States Army during World War II. They were designed as successors to the M4 Sherman. The standard main weapon for production versions of these designs was to be the 76 mm M1. In July 1943, on the basis that the 75 mm armed M4 was becoming obsolete, the US Army Ordnance Department requested that the 76 mm gunned T23E3 and T20E3 go into production the M27 and M27B1. However, the request was rejected and neither design was ever mass produced. The Army did not consider it necessary to interrupt M4 production for a vehicle for which they did not perceive a requirement and the introduction of the 76 mm gun to the tank force was opposed by the Armored Ground Force. Successive evolution of the basic design culminated in the M26 Pershing.

Almost immediately after the M4 Sherman was standardized, the US Ordnance Department started work on a successor. The Ordnance Department had already been working on a heavily armored infantry tank design for the British, using M4 parts. The new project was started on the 25 May 1942, it was originally designated M4X. The specification was 32 short tons, "automatic" 75mm gun, of armor and a top speed of
After a wooden mockup produced by Fisher, Ordnance (in agreement with Armored Force Board) set out three pilot models to be built with different combinations of armament but interchangeable turrets. All would use the Ford GAN V 8 engine driving Hydra matic transmission through a torque converter. The T20 would have the 76mm gun, the T20E1 the automatic 75mm and the T20E2 a 3 inch gun. T20 and T20E1 would be fitted with horizontal volute spring suspension (HVSS) but the T20E2 would have had torsion bar suspension. Starting with the T20, the Ordnance Department initially developed three series of improved medium tank prototypes, the T20, T22, and T23. The main differences between the T20, T22 and T23 lay in the choice of transmission. The T20 used a torque converter fluid drive, the T22 a 5 speed mechanical drive similar to the M4 drive, and the T23 used an electric drive. All moved the transmission to the rear of the vehicle eliminating the need for a driveshaft running the length of the vehicle. The driveshaft used in the M3 and M4 vehicles forced the turret to be mounted higher increasing the vehicle height.

With standardization of the M27 rejected, the Ordnance Department continued designing improved tanks, this time armed with 90 mm guns. The immediate result of this line of development was the T25 series – essentially a slightly larger version of the T23 – and then the bigger, better protected T26. The T26 further evolved into the T26E3, and was ultimately standardized as the M26 Pershing and accepted into service in 1944.