T20 Medium Tank - Design and Development

Design and Development

Almost immediately after the M4 Sherman was standardized, the US Ordnance Department started work on a successor. The Ordnance had already been working on heavily armored infantry tank design using M4 parts for the British. The new project was started on the 25 May 1942, it was originally designated M4X. 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 & M4 vehicles forced the turret to be mounted higher increasing the vehicle height.

Within each different prototype series, a variety of different suspension and armament configurations were tried out, for example, the T20 had an early version of the HVSS suspension later employed on the M4 Sherman, whereas the T20E3 had torsion bar suspension.