Fluid pressure clutch

A clutch mechanism for rotatably coupling a pair of shafts comprising:

• first and second frictional engaging means each rotatively fixed, respectively, to one of said shafts;
• fluid pressure means for establishing frictional connection between said first and second frictional engaging means, said fluid pressure means comprising pressure chamber means and fluid pressure source means for admitting fluid under pressure to said chamber means;
• rotary valve means comprising a first and a second valve component rotatable relative to each other and each rotatively coupled, respectively, with one of said shafts;
• said rotary valve means being arranged so that at at least one relative angular position between said first and said second valve components, the flow cross-section defined through said rotary valve means is at a minimum value so that fluid pressure medium admitted to said chamber means by said fluid pressure source means can assume a level prohibiting slippage between said first and second frictional engaging means only when said valve components assume a certain relative angular position and when said pair of shafts are set in a defined relative angular position due to the defined relative angular position of said valve components.