Timing belt drive - Operating characteristics

The quality of the description and prediction of the behavior of mechanical systems obviously relies on precise knowledge of the components and on close observation of the physical phenomena developed during operation. The previous dossier emphasized the description of the components of a toothed belt drive. The present dossier deals with the observation of behavior in the most classic cases of use and the characterization of a belt.

The toothed belt drive is based on the meshing of "flexible" teeth on a deformable belt core with supposedly rigid pulley teeth. In practice, however, a number of factors influence the way this meshing is achieved, and actual operation differs from that theoretically envisaged. In particular, the synchronism of motion transmission is not perfectly ensured, and small fluctuations around an average occur: a transmission error is introduced. During meshing and, more generally, during operation, the elements are excited by mechanical stresses: they begin to vibrate and produce an acoustic emission. What's more, as the torques to be transmitted become greater, the conditions of equilibrium during meshing are no longer ensured: tooth jump occurs. Last but not least, meshing transmission also gives rise to slippage at the interface between elements, and consequent dissipation of mechanical energy: the transmission efficiency needs to be determined, as does the operating temperature.

Determining the characteristic quantities of a toothed belt takes into account the nature of the belt's constituents and its use: specific methods must be introduced to measure these quantities. Moreover, during operation, these parameters change and the belt itself deteriorates: the most common degradations are listed here.