Patent ID: 8888623

Claim:
An auto-tensioner comprising: a cylinder having an open front end and a rear end wall; a plunger axially slidably inserted in said cylinder, said plunger having a closed front end protruding from said cylinder and an open rear end which is located in said cylinder, said plunger having an internal thread on an inner periphery thereof; a screw rod having an external thread formed on an outer periphery thereof and inserted in said plunger with said external thread of said screw rod in threaded engagement with said internal thread of said plunger, said screw rod having a rear end protruding from said open rear end of said plunger; a seat member axially slidably mounted in said cylinder between said screw rod and said rear end wall of said cylinder so as to be in abutment with said rear end of said screw rod, said seat member being rotationally fixed to said cylinder; a return spring having one end thereof supported by said screw rod and biasing said plunger outwardly of the cylinder, whereby said closed front end of said plunger presses a chain or a belt; an elastic member mounted between said seat member and said rear end wall of said cylinder so as to be compressible in an axial direction of the cylinder, thereby supporting and biasing said seat member in the axial direction of the cylinder toward the open front end of the cylinder; and a holder holding said elastic member in a compressed state, wherein said elastic member has an axial rear end surface facing said rear end wall of said cylinder, wherein said seat member has an axial front end, and wherein said holder comprises: a bottom portion supporting said axial rear end surface of said elastic member; side pieces extending axially from an outer edge of said bottom portion toward said seat member; and engaging pieces extending radially inwardly from distal ends of said side pieces, respectively, and engaging said axial front end of said seat member, thereby restricting the movement of said seat member.