RING CAM AND FLUID-WORKING MACHINE INCLUDING RING CAM

摘要

A fluid-working machine comprising a ring cam (1), at least one piston (11) defining a working chamber, and at least one valve (19, 21) associated with the or each working chamber for connecting the working chamber alternately to low and high pressure manifolds(23, 25) in phased relationship to cycles of working chamber volume. The ring cam has a wave-like cam working surface for operative engagement with the at least one piston. The waves of the wave-like cam surface each having a leading face (70) and a trailing face (72) and discontinuities (4), such as apertures (4) to retain bolts (3), are located in the working surface on whichever of the leading face and the trailing face the at least one piston does least work during normal operation resulting from the flow of fluid into and out of the working chamber in phased relationship to cycles of working chamber volume. As a result, there is reduced wear on cam following elements, such as piston rollers (9).