Abstract: A drive mechanism for revolving the turret of a searchlight assembly. The turret is rotated in an oscillating manner over an arc of less than 360.degree.. It is particularly characterized by smooth reversal allowing the driving of a high inertia turret without rapid motor overload and failure as characterized by other prior art methods of driving such mechanisms. A partial cylindrical track is concentrically disposed about the axis of rotation and attached to the turret. In the preferred embodiment, a link chain is welded along the bottom of the track, being folded back on the ends in a tear-drop shape. A drive sprocket on a swing arm is held into engagement with the chain and driven by a constant speed motor. The sprocket alternately drives along the inside of the chain and the outside of the chain smoothly traversing between the positions around the tear-drop ends to cause a smooth deceleration and acceleration.