Clutch with piston modulating valve

A multi-disc hydraulically operated friction clutch, comprising:

• a housing;
• sets of driving and driven discs alternatingly mounted in said housing for engagement and disengagement;
• a central shaft operatively connected with one of said sets of said discs, while the other said set is operatively connected with said housing;
• a plunger axially movable in said housing;
• a pressure disc mounted in said housing for operative interaction with said sets of discs;
• intermediate spring means normally urging said pressure disc from said plunger;
• hydraulic power means adapted to supply pressurized working fluid beneath said plunger and to displace it axially against the effort of said intermediate spring means, for said plunger to displace said pressure disc, so that the latter should compress said sets of discs to effect engagement of the clutch;
• controllable valve means positioned in through-going openings in said plunger adjacent to the periphery thereof and adapted for cooperation with said pressure disc, on the one hand, and with said housing, on the other hand, upon axial displacement of said plunger and said pressure disc;
• said valve means normally closing said openings in said plunger with the clutch disengaged and with the plunger moving through an idle stroke and opening said openings for draining of the working fluid therethrough in accordance with a characteristic predetermined by the shape of said valve means, in proportion with the relative displacement of said plunger and said pressure disc, so that the closer said plunger and said pressure disc are brought together, the greater is the degree to which the state of the valve means and the flow capacity thereof is altered:
• resilient return means connected with said plunger for returning same into the initial position thereof upon discontinuation of the action thereupon of said hydraulic power means at disengagement of the clutch.