Valve with a spool for the control of the start and of the stop of a hydraulic motor in which an oblong spool is mobile within an oblong seat obtained in a body, the movement of the spool being controllable in two opposite directions of movement by means of control means, the spool being housed within an intermediate portion of the seat in which the intermediate portion has a section size essentially equal to the section size of the spool, the spool being equipped with at least one intermediate portion with respect to a first end and to a second end with a section size smaller than the section size of the intermediate portion of the seat giving rise to the formation of an interstice intended for the reciprocal connection of at least one first duct and a second duct.