Abstract: A step-by-step controlled servomechanism of the type comprising a drive element movable provided with a plurality of receiver ports, and a fixed distributor to supply said receiver ports and having a number of transmitter ports capable of being connected, in pairs, respectively to the low pressure and to the high pressure, a fixed manifold having a plurality of manifold ports capable of communicating with the chamber of the drive element, all the receiver ports being capable of being made to open in succession into one of said manifold ports, selecting means capable of connecting, in succession by permutation and simultaneously, at least one pair of transmitter ports to the high pressure and to the low pressure, respectively, and at least one manifold port to the chamber of the drive element.

Abstract: Step by step controlled servomechanism of the cylinder-type comprising a drive element movable in a case which it divides into two chambers and provided with a plurality of receiver ports, a distributor adapted to be put in communication with the high pressure and the low pressure and to supply said receiver ports, wherein said distributor is fixed and provided with a number of supply or transmitter ports at least equal to three but independent of the number of receiver ports, the transmitter ports being capable of being connected by permutation, in succession and in pairs, respectively to the low pressure and to the high pressure, the distance between the receiver ports and their length, on the one hand, the distance between the transmitter ports and their length, on the other hand, being such that, by the step by step displacement in one direction of the drive element, on one hand, it is possible to bring each time at least one receiver port between the two transmitter ports of a pair in such position that