Abstract: A belt tension adjusting device having a fixed member, a support shaft extending vertically from the fixed member and a pulley arm having a boss formed with a boss. The support shaft is received in the bore to rotatably support the pulley arm. A damper mechanism is mounted between the support shaft and the boss for damping a pivoting motion of the pulley arm. A pulley is mounted on the pulley arm. A tension adjusting spring is coupled to the pulley arm for biasing the pulley to impart tension to a belt. A bearing is provided for receiving radial loads produced when the pulley arm pivots. Part of the bearing is located in part outside the boss.

Abstract: A belt tension adjusting device having a pulley arm having a bore formed with threads, a fixed member and a support shaft extending upwardly from the fixed member into the bore in the pulley arm. A bolt made of a synthetic resin is axially movably mounted on the support shaft and held in thread engagement with the threads formed on the bore. An elastic member is mounted in the bore between the bolt and the support shaft or a member integrally mounted on the support shaft for biasing the bolt in an axial direction. A coil spring is mounted on the pulley arm and having one end thereof in engagement with the pulley arm and the other end with the fixed member.