Abstract: Disclosed is a hydraulic servomechanism wherein the motion of a driven element is synchronized with the motion of a command element by detecting any phase difference between the movement of the driven element and that of the command element, controlling the flow rate of a hydraulic fluid being fed to the driven element with a directional and flow control valve in proportion to the detected amount of phase difference and also controlling the flow rate of the hydraulic fluid being fed to the hydraulic servomechanism with a pressure compensation valve in proportion to the variation in the load exerted on the driven element.

Abstract: An electric-hydraulic pulse motor having an improved rotary guide valve means is provided. In the rotary guide valve, a valve member for controlling the supply of fluid to the hydraulic motor is adapted to be shifted for performing the controlling function by the effect of pressurized fluid. The valve member is supported on a valve shaft or a signal input shaft which is to be actuated by a conventional electric pulse motor or the like so that the valve member rotates with one of the two shafts but is allowed to be shifted transversely thereto to either of two eccentric positions by the effect of the pressurized fluid. Control for shifting the valve member is obtained by arranging the two shafts so that the relative movement between the two shafts controls the pressurized fluid so as to move the valve member to the desired one of the eccentric positions.