The present invention relates to a hydraulic self-closing two-way valve of the type including a housing forming a valve seat and a locking body cooperating with the valve seat and connected to and actuated by an actuating piston which is loaded by pressurized fluid and is displaced in a recess provided in a cover connected to a control block in which the valve is inserted. 
Such valves are formed as built-in valves and are accomodated in control blocks in accordance with a lay-out plan PD 81 010/9.84 of the assignee. 
In order to provide a self-closing or automatically-closing valve arrangement an additional means is required, which is provided on the actuating piston cooperating with the locking body of the valve; that additional means in the switch-off position of the control valve, in which the control pressure is blocked up to the built-in valve, causes the closing of the locking body of the valve. 
In the valves of the foregoing type, the actuating piston is accomodated in the cover and is connected, in the opening direction of the locking body, with that body in a locking fashion by means of coupling elements.  Due to the connection of the coupling elements the cover is comparatively large.  Therefore specific designs have been required for self-closing two-way seat-type valves, which has been quite expensive.