Lash adjuster for valve actuator

摘要

A lash adjuster (A) in a valve actuator includes a lifter body (11) having an end plate (12) having its top surface in contact with a cam (1) and formed with a threaded hole (15) in its bottom surface. An adjuster screw (16) is inserted in the threaded hole (15) with its external thread (16a) in engagement with the internal thread (15a) of the threaded hole (15). An elastic member (17) is mounted in the threaded hole (15) over the adjuster screw (16) to bias the adjuster screw (16) axially downward. Both of the threads (15a,16a) have a sawtooth-shaped section with its pressure flank having a greater flank angle than its clearance flank. One of the pressure flanks is formed with a satin-finished rugged surface which is covered by a hard film which is non-reactive with a low-friction oil. With this arrangement, even after the threads have become worn, the friction coefficient between the thread surfaces is kept substantially constant.