Abstract: A hydrostatic clutch, includes coaxial driving and driven rotative members, so that when in the clutched condition rotative power is transferred from the driving to driven member. The clutch includes a plurality of pistons bearing upon an inclined cam, and move in a reciprocating motion when the cam which is coupled to either the driven or driving shaft, rotates. A second cam also driven by the driven or driving members, is adopted to be disposed with respect to the mobile member which drives it, into two positions offset by 180.degree.. The second cam acting upon a suction valve controlling the intake of hydraulic fluid, via opposing springs. At least one double stage or delivery valve is carried by the same mobile driving or driven member. A fixed casing is connected to the mobile member carrying the delivery valve or valves, through a rotating seal. The fixed casing is connected via a plurality of hydraulic channels to various hydraulic fluid regulation member.