Valve actuating apparatus for minimizing the need for lash adjustment

摘要

A cam unit and a follower at the upper end of the valve stem are configured so that the surfaces between which lash is measured are for all intents and purposes removed or segregated from the surfaces used for effecting valve movement. The modified interaction between the cam and the surface the cam bears against compensates for reduction in valve lash. The segregation is achieved by employing a button having a reduced area engaged by the ramp portions of the cam unit, the ramp portions having a width at least as great as that of the button. In one embodiment, the button is softer than the ramps. Provision is also made for dimensionally correlating the working surface of the cam and follower with the amount of load needed at any given moment to open or close the valve.