Torsionally resilient coupling

In a torsionally resilient coupling comprising two concentric members each exhibiting co-operating grooves forming block cavities, a plurality of solid cylindrical blocks of resilient material accommodated within said cavities for transmitting torsional forces applied to one of said concentric members to the other concentric member, and end plates defining the axial extent of said cavities and preventing axial deformation of said blocks of resilient material at each end on loading thereof;

• the improvement wherein each of said grooves is defined by a central section which extends along an arc of a circle and whose entire surface is in contact at all times with the associated solid cylindrical block of resilient material, said central section developing at each end thereof into a straight flank extending tangentially relative to said circle and at an angle to a diametrical plane of said circle, said blocks each having a diameter dimensioned such that said blocks contact said flanks only under torque load conditions, said blocks being subjected only to radial deformation under said torque conditions due to being equal in length to that of the cavity into which their diameter is a light driving fit, and wherein said angle of each said tangential flank is such as to provide the desired torsional deflection and coupling stiffness, a relatively small angle providing a low torsional deflection and high stiffness, and a larger angle providing a higher torsional deflection and lower stiffness.