M27 Medium Tank

The M27 medium tank was born out of the T20 program. After the M4 series of tanks went into production, consideration immediately turned to its successor. The US Army Ordnance Department was given the go-ahead to start work on an improved medium tank in May 1942.

Broad outlines called for a 32-ton tank armed with an automatic 75mm gun with HVSS suspension and capable of a speed of 25mph.

The T20 was developed first, but transmission problems led to the tank being cancelled and the best ideas transferred to the T22. This was essentially a T20 with the five-speed transmission from the M4 Sherman. The solutions proved unsatisfactory and this led to the project being cancelled as well.

At the same time as the T22 was authorized, work began on the T23. It was essentially a T20 fitted with the tried and tested vertical volute suspension (VVSS) as used on the M4 Sherman, and an electric transmission from General Electric. It was initially to have 75mm automatic, 3-inch and 76mm gun versions, but the 75mm automatic and 3-inch versions were cancelled before prototypes were built. In its final form, the T23 has a turret fitted with an all-round vision cupola for the commander and a rotating hatch for the loader. The hull has a new single-piece, flat plate at a 47-degree angle.

Many of these design improvements were incorporated into late-production M4 Sherman tanks which had a 47-degree hull front and mounted the T23 turret with minor changes. A limited procurement order of 250 T23 medium tanks were ordered and were produced between November 1943 and December 1944 by Detroit Arsenal. These were to be standardized as the M27 medium tank when production started in earnest.