Spannrad für Zugmittel

摘要

This invention concerns a device for putting a tension element under tension, preferably a chain, consisting of a traction wheel, preferably a sprocket (1) mounted to rotate on a hollow axle (3). A hollow piston element (5, 6) is arranged within a hollow axle (3) which is sprung against the hollow axis (3) by means of a spring element, preferably a coil spring (12). The piston element (5, 6) is arranged in a piston chamber (4) wherein the longitudinal axis of the piston element (5, 6) is arranged perpendicular to the traction wheel axis. Preferably motor oil is provided in the cavity (7) of the hollow piston element (6) to hydraulically dampen the piston element (6). So that the enlargement of the radial extension of the spring element (12) can occur independently of the radial extension of the cavity (7), it is proposed that the piston element (5, 6) comprise an external piston (5) which is sprung against the hollow axis by the spring element and an external piston (6) which is arranged concentric to the external piston (5); the internal piston (6) is provided on the face side with a stop (11) for the hollow axle (3).