Abstract: A belt tension adjusting device has a stationary fulcrum shaft, an arm pivotally supported on the fulcrum shaft through a slide bearing formed of a synthetic resin, a tension pulley mounted on the arm at one end thereof for tensioning a belt, and a damper having a piston rod abutting the arm on the other end thereof. The tension pulley is pressed against the belt by pivoting the arm under the force of the piston rod, thereby adjusting the tension of the belt. The inner peripheral surface of said slide bearing, which is in slide contact with said fulcrum shaft, is formed so as to have a surface roughness RA of not more than 6.3 &mgr;m. The slide bearing is formed of a resin composition comprising 65-85 vol % of a thermoplastic polyimide resin, an aromatic polyether ketone resin or a mixture of the resins, and 15-35 vol % of a tetrafluoroethylene resin.

Abstract: A belt tension adjusting device is provided which even if the slide bearing is heated to a high temperature by heat of an automotive engine, it is less likely to get worn and the fulcrum shaft will not seize. The belt tension adjusting device has a stationary fulcrum shaft, an arm pivotally supported on the fulcrum shaft through a slide bearing formed of a synthetic resin, a tension pulley mounted on the arm at one end thereof for tensioning a belt, and a damper having a piston rod abutting the arm on the other end thereof. The tension pulley is pressed against the belt by pivoting the arm under the force of the piston rod, thereby adjusting the tension of the belt. The inner peripheral surface of said slide bearing, which is in slide contact with said fulcrum shaft, is formed so as to have a surface roughness RA of not more than 6.3 &mgr;m.