Toothed-belt drive

A toothed belt drive consists of a belt that drives a number of rotating pulleys and accessory elements such as tensioners and winders. From a global point of view, the presence of active teeth on the belt, which mesh with the teeth on the pulleys, ensures an average transmission known as synchronous. But if we look a little more closely at the angular movement on the receiving pulleys, and in particular at all the variations in resisting torques, angular deviations of the pulleys from their theoretical positions appear – This is known as transmission error – and synchronism is not guaranteed.

Already in quasi-static operation, internal forces and preloads condition the loads applied to the teeth during operation, along the arcs of the belt winding on the pulleys. In motion, however, variations in excitation, either of motion or of force, lead to dynamic responses and consequent variations in force, which affect service life, transmission error and noise.

Definitions. Geometry" folders and "Operating characteristics". have shown that timing belts are very rigorously defined, technological progress is noticeable and the apprehension of using a rubber or polymer-based component is fading. On the other hand, applications are becoming better defined, particularly with regard to conditions of use, and computing resources are becoming increasingly well-suited to numerical simulations which, in part, free us from constraining experimental conditions.

The aim of this dossier is to present the various calculation steps currently possible, and to give application engineers the means to build a documented argument when designing toothed belt drives. First, we summarize simple or global pre-sizing methods. We then present quasi-static load distributions between the teeth that transmit the forces. The effect of transmission parameters is discussed. In the [BM 5 688] file, an approach to dynamic effects is proposed.