Abstract: A rotary device, for example in the form of a gear wheel, comprises a hub (2) and an outer element (4) carrying teeth (28). The outer element (4) is provided with resilient fingers (20) which frictionally engage cam surfaces (38) provided on the hub (2). Relative rotation between the hub (2) and the outer element (4) is resisted by deflection of the fingers (20). Relative rotation between the hub (2) and the outer element (4) is limited by engagement between projections (32) and recesses (34). A combination of torsional spring force created by the flexible fingers together with friction between the fingers (20) and the cam surfaces (38) and between the recesses (46) and the projections (32) provide a damping effect which serves to limit the transmission of torsional vibrations between the hub (2) and the outer element (4).

Abstract: A valve control mechanism is disclosed which permits either or both of (a) axial displacement of the camshaft of an internal combustion engine, and (b) phasing of the camshaft (and hence of the valve operation)—i.e. an advance/retard function. The mechanism preferably includes a piston housed within a cylinder, this arrangement itself being mounted within a front end camshaft pulley. The piston is under hydraulic control, preferably governed by a microprocessor. A mechanical coupling between the piston and the camshaft translates the axial movement of the piston into one or both of axial displacement of the camshaft and relative advancement/retardation of its rotation.