Abstract: A clutch arrangement for rapid disengagement of two elements in a transmission system when a chosen torque is exceeded. The first element is a conical shaft end that carries a corresponding sleeve which, in turn, carries externally at its ends two mutually separated ball bearings with a force transmission ring disposed therebetween. The second element, an annular force transmission body, surrounds and is carried by the ball bearings and includes a pressurisable hydraulic chamber which, when pressurised, causes a reduction in the inner surface diameter of the body so that the body is brought into force transmitting engagement with the outer surface of the ring. The sleeve carries a dogging element which is adapted to act on an element carried by the body for depressurising the hydraulic chamber upon relative rotation between the body and the sleeve such that, when the chosen torque is exceeded resulting in the relative rotation, the chamber is depressurised, and the ring and the body pass free from each other.

Abstract: A coupling arrangement for coupling a driving unit (1) to a driven unit (2) includes a combination of a shear coupling (7) which acts between the units and which fails immediately an overload occurs, and a brake coupling (13) which is adapted to become active between the units (1, 2) when the shear coupling (7) fails.