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The T57 120mm gun tank was designed in an attempt to produce a tank that was lighter than the Heavy Tank T34 or 120mm gun combat tank M103, taking advantage of an oscillating turret to reduce weight.
The T57 had a number of advanced features. The turret and gun were the most radical. It used a 120mm gun in a rigid mount, so there was no recoil mechanism. Instead the low profile turret would oscillate. The smaller lower part was fixed to the turret ring, and would remain static. The larger upper part was free to rock backwards, and there was a sizable gap between the hull and the bustle to prevent it hitting hit the hull. The gun had to be modified to operate without the recoil forces, which were normally used to open the breechblock, so a hydraulic system had to be developed instead.
The 120mm gun used on the T57 was rigidly mounted to the turret. There were no elevation controls for the gun itself. Instead the entire upper part of the turret would move to elevate the gun.
The oscillating turret was intended to allow a heavy gun to be carried on a relatively light vehicle. The Heavy Tank T34 carried a 120mm gun at a combat weight of 143,600lb. The 120mm gun combat tank M103 carried a lighter gun at a combat weight of 125,000lb. The T57 had a combat weight of 120,000lb, so the weight savings were fairly trivial.
The T57 used an automatic loader, which could carry eight rounds of fixed ammo in a rotary drum, which carried out the complete loading process as well as removing the previous cartridge case.
The T57 only needed a four man crew - the driver, gunner, commander and loader. Normally the loader's job was to place the correct shells in the rotary drum for the auto-loader. The tank could only carry 18 rounds.
Work on the T57 didn’t get terribly far. Two turrets were produced, and one was installed on a T43E1 (M103) chassis, but the entire programme was cancelled on 17 January 1957 before the tests began. The turrets were both scrapped and the T43E1 chassis returned to storage.
Stats
Length with gun: 449.3in
Hull Length: 275.3in
Hull Width: 143in
Height: 104.5in
Crew: 4
Weight: 120,000lb combat loaded
Engine: 810hp Continental AV-1790 12 cylinder V-12 engine
Max Speed: 22mph
Max Range: 80 miles road range
Armament: One 120mm Gun T179 and coaxial .30in gun in turret, .50in MG on turret hatch
Armour
| Armour | Front |
Side |
Rear |
Top/ Bottom |
Turret |
127mm |
137mm |
51mm |
38mm |
Hull |
114-127mm |
44-51mm |
25-38mm |
25mm |