Valve crosshead assembly with wear-reducing contact pad

摘要

In accordance with preferred embodiments of the invention, a disc-shaped contact pad of ceramic material is disposed within a recess formed in the top surface of a metal valve crosshead. The pad is held in the recess by a retainer that clips onto the crosshead. The retainer is designed to maintain only a light pressure on only a narrow shoulder of the pad to keep it seated, and does not, itself, experience any dynamic loading. Furthermore, by the provision of a circumferential clearance between the pad and both the wall of the crosshead recess and the retainer, the need for precision machining of the ceramic material can be avoided. Additionally, a reduction of frictional sliding forces imposed on the crosshead, and in turn upon the valves, by the rocker lever is achieved by the ceramic pad, so that resultant frictional side loading is not imposed on adjacent valve components to a significant extent.