This International Standard specifies the principal characteristics of synchronous endless belts and pulleys for use in synchronous belt drives¹⁾ for mechanical power transmission and where positive indexing or synchronization may be required.

The principal belt and pulley characteristics include:

• nominal belt tooth dimensions;
• belt tooth pitch spacing;
• belt length and width dimensions;
• belt length-measurement specifications;
• pulley groove dimensions and tolerances;
• pulley diameter and width dimensions and tolerances;
• pulley quality specification.

1) Synchronous belt drives have been known by various titles in the past: for example, timing belt drives, positive belt drives, gear belt drives.