Oscillating turret

An oscillating turret is a form of turret for armoured fighting vehicles, both tanks and armoured cars. The turret is unusual in being made of two hinged parts. Elevation of the gun relies on the upper part of the turret moving relative to the lower part.

Oscillating turrets have only rarely been used. Their only widespread use was on two French designs: the AMX-13 light tank and the Panhard EBR armoured car; the Austrian SK-105 Kürassier uses a turret developed from the AMX-13.

The turret consists of upper and lower parts, joined by a trunnion. The gap between these two parts is covered by a distinctively visible rubber or canvas bellows.

The gun itself is fixed to the upper part of the turret. Elevation of the gun is achieved by tilting the entire upper part of the turret. Traverse is achieved conventionally, by rotating the turret.

There are three major advantages: high gun placement, smaller turret size and simpler fitment of an autoloader. High gun placement allows for better depression angles, reduces the exposed part of the tank when using hull down positions, and reduces the vertical gap between line of sights and line of the gun. The fact that fully elevated gun does not cross the turret ring allows to reduce turret ring diameter hence width of the vehicles hull and/or mounting the more powerful gun. Autoloader mechanism is simpler and works more reliably when the gun is not moving relative to it.

The initial claimed advantage of oscillating turrets was that of reducing the turret size for a large main battle tank gun. In the 1950s, tanks were rapidly growing more heavily armed, larger and heavier. Western armed forces were trying to catch up with the increasingly formidable Soviet tanks, such as the T-55. Weight was the main problem, particularly where this then required extra engine power and stronger transmission. As the thickest armour is generally on the turret, reducing turret size appeared to be a worthwhile goal.

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