Friction coupling with fluid operated diaphragm

Claim 1

A friction coupling comprising: two co-axial relatively movable members having opposing coupling surfaces disposed one inside the other, the outer one of said members having a plurality of recesses in the form of channels parallel to the axes of said members in its coupling surface and also annular hydraulic fluid inlet means on its inner surface communicating with said recesses; annular hydrulic fluid supply means fixedly disposed externally of and coaxially with respect to said outer member and simultaneously communicating with said inlet means via circumferentially spaced through bores in said outer mEmber; a thin intermediate part in the form of a thin cylinder located between the opposing coupling surfaces of said members and having a plurality of protuberances each fitting into one of said recesses without completely filling it; and sealing means located between the intermediate part and said coupling surface of said outer member to form a sealed expansible chamber therebetween, said sealing means including sealing rings disposed in annular grooves formed in the inner surface of the outer member, which groves are so located that the sealing rings bear on the cylindrical intermediate part near its ends, and the depth of which grooves is such that the sealing rings remain compressed against the intermediate part when inward deformation of the intermediate part is a maximum.