Abstract: This directional valve comprises a closing element (1) rotatively mounted in a fixed sleeve (5) disposed in a body (2) with interposition of an annular element (4) between the closing element and the sleeve. Means are provided for locking the annular element against rotation in normal use and for permitting the driving of the annular element by the closing element in the event of a seizing of the closing element in the annular element. These locking means comprise a device (12) having a push member (13) mounted laterally on the body at one end of the closing element (1) and extending in a direction perpendicular to the closing element (1), resilient means (15) being provided for biasing the push member against a rocker (30) inside the body, the thrust of which is applied to locking balls (21) which project from recesses (24) provided in an end of the annular element (4).

Abstract: The servovalve has in combination:(a) a rotary torque motor (1) having a limited angular movement;(b) a hydraulic distributor (2) capable of supplying fluid to the actuator and comprising a rotary shaft (10) coaxially connected to the torque motor (1);(c) a detector (3) of the angular position of the shaft (10) coaxial with said shaft, so that the motor (1), the distributor (2) and the detector (3) have their rotating parts (7, 10, 3a) coaxial and connected to rotate together; and(d) an adder (4) associated with an electronic amplifier (5) connected to the torque motor (1) and capable of receiving a given control voltage (E), the output of the detector (3) being connected to the input of the adder (4).This arrangement permits giving the same rotating movement to all the moving parts of the servovalve and consequently has the advantage of eliminating the play and friction which have an adverse effect on the precision and reliability of prior mechanisms.