Patent ID: 7013855

Claim:
A lash adjuster adapted to be mounted in a valve actuator including cams, said lash adjuster comprising a lifter body adapted to be axially slidably mounted between one of said cams and a stem of a valve, said lifter body including an end plate having in its bottom surface a threaded hole having a closed top and formed with an internal thread on its inner wall, an adjuster screw having an external thread on its outer periphery and inserted in said threaded hole of said lifter body with said external thread engaging said internal thread, and an elastic member mounted in said threaded hole between said closed top and said adjuster screw for biasing said adjuster screw axially downwardly, said internal thread of said lifter body having a first pressure flank and a first clearance flank, said external thread of said adjuster screw having a second pressure flank and a second clearance flank, said first and second pressure flanks being arranged to be pressed against each other while said adjuster screw is being biased axially upwardly, said first and second pressure flanks having a greater flank angle than said first and second clearance flanks, respectively, one of said first and second pressure flanks being formed with a satin finished rugged surface covered with a hard film which has a substantially uniform thickness and is non-reactive with a low-friction oil.