Patent ID: 8393987

Claim:
A chain tensioner comprising: a cylindrical cylinder having open and closed ends; a cylindrical plunger axially slidably inserted in said cylinder; a return spring biasing said plunger in a protruding direction from said cylinder, said plunger having an open end inserted in said cylinder and a closed end and formed with an internal thread on the inner circumference; and a screw rod having an external thread that is in threaded engagement with said internal thread of the plunger; wherein a portion of said screw rod protruding from said plunger abuts a rod seat provided in said cylinder; wherein said external thread on the outer circumference of said screw rod is formed by rolling; wherein a cylindrical intermediate portion having an outer diameter smaller than the diameter of the root of said external thread is provided on a portion of said screw rod protruding from said plunger; wherein a contact surface to be brought into contact with the rod seat is provided on the axial end face of said intermediate portion; and wherein said contact surface is a forged contact surface.