Transmission Error due to Resonance in Synchronous Belt Drive With Eccentric Pulley

In synchronous belt drives, it is generally difficult to eliminate pulley eccentricity, because the pulley teeth and shaft hole are produced separately. This eccentricity affects the accuracy of rotation transmission, so that the belt tension changes during a single rotation of the pulley. This in turn affects the occurrence of resonance in the spans. In the present study, the transmission error in a synchronous belt drive with an eccentric pulley in the absence of a transmitted load was experimentally investigated for the case in which the spans undergo first-mode transverse vibration due to resonance. The transmission error was found to have a component with a period equal to the displacement of the span, in addition to a component with a period of half the displacement of the span. During a single rotation of the pulley, the magnitude of the transmission error increased, and its frequency decreased, with decreasing belt tension. The transmission error exhibited the large value when two frequency conditions were satisfied: one was that the meshing frequency was within the range of span frequency variations due to the eccentricity, and the other was that the minimum frequency of the span was close to an integer multiple of the rotation frequency of the pulley. Even if both of these conditions occurred, if the range of span frequency variations due to the eccentricity was larger than 13 Hz, the transmission error could be eliminated by adjusting the belt tension so that the average frequency of the span corresponded to the meshing frequency.