Abstract: A hydraulic power steering rotary valve of generally conventional construction characterized in that the on-center characteristics of the valve are governed by an arrangement of rolling elements and pairs of notched elements arranged to produce a detent action between the input shaft and the sleeve or driven member. One notched element of each pair is fixed to a carrier which is connected to the sleeve or driven member by a securing device. During assembly, the carrier is free to move under the influence of springs acting on the notched elements and thereby take up a position such that after completion of assembly the notched elements and rolling elements are precisely in the correct position to provide the required detent action.