Abstract: A machine for grinding the metering edge contours on edges of axially extending grooves of a power steering valve input-shaft by means of a cylindrical grinding wheel, the machine being constructed to hold and rotate the input-shaft and to increase and decrease cyclically the distance between the axis of the input-shaft and the grinding wheel several times during the revolution of the input-shaft to grind metering edge contours to produce symmetrical sets of clockwise and anticlockwise metering edge contours. The input-shaft is centrelessly supported by means of surfaces tangentially contacting the outside diameter of the input-shaft. Two such surfaces are axially displaced on either side of the ends of the grooves in the input-shaft and are arranged one on each side of the grinding wheel on that side of the input shaft adjacent the grinding wheel.