This valve has been designed for use with two cylinders in sequence for reversible plough to obtain the automatic alignment of load and its overturning. Operating instructions: first the alignment cylinder B starts lining up the load. Once it reaches the end of stroke, the overturning cylinder A starts the rotation. Upon the completion of this the alignment cylinder B takes the plough back into its working position. It is possible to interrupt the overturning cycle at any point and retake the plough to the working position.