Abstract: A hydro-mechanically operated reciprocating spindle for a machine tool is disclosed in the environment of a vertical gear shaper. The spindle comprises a piston which is slidable in a cylinder and which carries a cutting tool at its bottom end. The spindle-piston has two faces of different area to which hydraulic fluid under pressure is directed, the larger area face being used to drive the spindle downwardly in the cutting stroke, and the smaller area face being used to drive the spindle upwardly in the return stroke. Further, the spindle-piston has an axial bore which receives a vertically reciprocable valve. The valve is reciprocated by linkages driven by a rotating shaft, and the arrangement is such as to drive the valve downwardly and thus to move the spindle downwardly at a controlled velocity and under a controlled hydraulic force, and then as the valve is moved upwardly the spindle is moved upwardly on the return stroke at preferably a higher velocity.