The T69 was a prototype American medium tank with an oscillating turret mounting a 90mm cannon with an eight-round drum autoloader.

[1] In the early 1950s, the United States Military began a design program to develop tanks that would replace those currently in service.

These tanks, however, were still very similar to vehicles of World War II era and did not make use of newer technologies that had begun to appear.

Further studies by the Rheem Manufacturing Company found that it would be possible to pair the T139 90mm gun with an autoloader if the equipment was mounted in an oscillating turret.

The upper part, or 'body', carries the gun moving up and down on a set of trunnions providing vertical traverse.

Turrets of this design allowed the use of autoloader mechanisms as the gun was fixed in place, meaning the loader did not have to be re-aligned with the breach after every shot.

The hull of the tank was made up of two parts: The front half was a long rounded casting of steel homogeneous armor, it was 4 inches (101.6 mm) thick and angled at 60 degrees, while the rear was welded steel armor plate.

This body was attached to a fully cast collar by trunnions, forming the fulcrum point of elevation and depression.

If needed, the entire turret roof had the ability to raise up via hydraulic systems and could rise to almost a full 90 degrees.

This allowed full access to the interior of the turret, easy removal of the gun and loading system, and quick ammunition resupply.

On each side of the turret, positioned just above the fulcrum point were the 'Frog's Eyes', the armored housings for the lenses of the stereoscopic rangefinder, as in other tanks of its day.

This meant that the vertically sliding breach slid up towards the turret roof instead of down towards the floor, avoiding collision with the loading mechanism.

Once fired, the empty shell was then passed along a chute to an ejection port in the turret bustle that automatically opened upon recoil of the gun.

Once the shell was clear, the port automatically closed when the gun returns to battery (recovers from recoil).

It was found, however, there was little clearance between the autoloading assembly and the turret ring for the loader to have access to this row of four extra rounds.

The tests were dogged by a high rate of component failure which prevented in-depth study of the automatic loading system and operation of the oscillating turret.

The one prototype produced is now preserved in the U.S. Army Armor & Cavalry Collection, Fort Moore, Georgia.