Helical synchronous belt drives are superior to conventional synchronous belt drives in terms of transmission and noise, however side tracking in helical drives is more problematic than in conventional drives due to the helical shape of the tooth trace. Helical synchronous belt runs on the pulley, while side tracking is occurred with offset, which is a difference in the axial direction between the belt on the driving pulley, and that on the driven Pulley, when the belt undergoes torque during operation. Therefore, the flange is generally fitted on the pulley to prevent the belt from running off the pulley. By using the flanged pulley, the side face of the belt is considered to result in wear because the belt is forced against the pulley flange. In the present study, the behavior of helical synchronous belt in the axial direction under torque was investigated when a flange was fitted to the driving or driven pulley. It was found that offset could be reduced by fitting a flange to the driving pulley alone, and that the quantity which pressed the belt to the flange could be reduced by fitting a flange to the driven pulley alone.
