Valve used to control the movement and locking of the actuator in both directions by realising the controlled descent of the load that does not escape dragged by its own weight, as the valve does not allow any cavitation of the actuator. It is insensitive to backpressure and is therefore used where normal overcenters do not function properly at load control, and allows the pressure set by the system to be used to operate several actuators in series. This type of valve differs in the position of the connections.