Patent ID: 7654924

Claim:
An auto-tensioner comprising: a housing having an open end and a closed bottom at another end; a cylindrical plunger having an opening that faces said closed bottom of said housing and slidably inserted in said housing with one end thereof protruding from said housing; a ring-shaped seal member mounted between an inner periphery of said housing and an outer periphery of said plunger for hermetically sealing oil in said housing; a screw rod mounted in said plunger so as to be coaxial with said plunger, said screw rod being a separate member from said plunger; a nut member mounted in said plunger so as to be coaxial with said plunger, said nut member being a separate member from said plunger, and said nut member being in threaded engagement with said screw rod; a return spring mounted between said nut member and said plunger and biasing said nut member and said plunger in a direction axially away from each other such that said nut member is biased toward said closed bottom of said housing and said plunger is biased away from said closed bottom of said housing; and a spring mounted between said screw rod and said closed bottom of said housing and biasing said screw rod in a direction away from said closed bottom of said housing.