Abstract: The present invention relates to variable output transmissions which utilize mechanical square wave generators. The square wave generator comprises a plurality of relatively rotatable driver gears mounted on a first common shaft, and a plurality of driven gears mounted to the bevel gears of a differential, the differential carrier and pinion thereof being fixedly mounted on a second common shaft. The driven and driver gear meshingly engage, the rotation of the driver gears imparting a relative pattern of rotation to the driven gears to cause the differential carrier and the second shaft to rotate with an angular velocity determined by the relative angle of mounting the driver gears. The output angular velocity of the generators is applied to the output shaft of the transmission such that by varying the relative angle of mounting the driver gears the output of the transmission may be varied.