Belt drive

The belt drive is a non-positive-locking power transmission device that uses friction to transfer force between the belt and belt pulley. The belt used can be a V-belt, a flat belt, or a toothed belt for positive-locking belt drives.
See Fig. 1 Belt drive

Belt drives are not used for control purposes but to transfer torque. They used to be used in conjunction with internal combustion engines to transmit relatively large torques from the crankshaft to several ancillary assemblies with a relatively low loss of energy and minimal maintenance requirements (in the form of re-tensioning). The belt drive was therefore a frequently used drive element due to the ease with which the required pump speed could be adapted to fixed drive speeds and the elasticity of the belt. Today, it no longer plays a major role in centrifugal pump engineering (also see Closed-loop control). and is only used to adapt power for waste water pumps. See Fig. 6 waste water pumps.