An improved drive system for machines incorporating air bearings is disclosed. The drive system eliminates backlash, introduces no vibrations or noise into the moving structures, requires no lubrication and excells in being compact and simple. The drive system essentially includes a stationary bar mounted in one axis of motion of the machine, a wedge member mounted for drivingly engaging the bar on one side, a preloader mounted for operatively engaging the bar on the opposite side, and a pair of springs urging the preloader to urge the wedge member into driving engagement with the bar. The drive system is coupled to a positioning servo system, which provides control of the drive system's position and speed. Preferably, the wedge angle of the wedge member is from about 15. degree. to about 30. degree.