Abstract: The invention relates to a hydraulic motor having a plurality of cubic capacities, and provided with individual cubic-capacity selectors associated with at least some of its cylinders, each selector being provided with a control member. According to the invention, the control member coupled to each of said individual selectors can be activated only in that range of positions of the cylinder associated with said individual selector which corresponds to the axis of said cylinder being in alignment with the crest of one of the undulations, and to positions that are angularly adjacent to the position in which said alignment is obtained. An application of the invention is to making a motor that is mechanically strong.