Gears are called positive gears and belt drives are called negative drives. Explain in detail.
The negative drive is an informal expression to describe 'friction drive'. The belt drive is based on friction between the disc and the belt, however positive drive is based on movements without slipping.
Not all belt drive system are 'negative drive'. We also have a positive drive belt system, in this special case, the belt doesn't slip over the driving disc but it rolls over teeth.