Patent ID: 8181615

Claim:
A lash adjuster for a swing arm type valve gear comprising a cylindrical body having a closed bottom end and fitted in a fitting hole formed in a cylinder head, an adjusting screw mounted in said body, said adjusting screw being formed, at a top end thereof, with a spherical pivot portion protruding in a protruding direction from a top end of said body, said pivot portion pivotably supporting one end of a swing arm, and a return spring mounted in said body and biasing said adjusting screw in the protruding direction from said body, wherein said body is formed with an internal thread on an inner circumferential face thereof, wherein an external thread meshing with said internal thread is formed on an outer circumferential face of said adjusting screw, and wherein said external and internal threads have a serration-shaped section so that a flank angle of a pressure flank thereof, which receives axial pushing load applied on the adjusting screw, is larger than a flank angle of a clearance flank thereof, wherein, between the bottom faces of said body and said adjusting screw, a perforated disc-shaped friction member is provided to contact the bottom face of the adjusting screw and to prevent the adjusting screw from rotating and moving in the protruding direction by a pressing force of said return spring, and wherein an engagement hole is formed in a top portion of said adjusting screw that protrudes from said body so that a turning tool can be engaged in the engagement hole.