A v-belt is a flexible and efficient power transmission device capable of transferring power from one shaft to another. It is known for its trapezoidal shape that wedges securely into the sheaves of a shaft. The unique shape of V-belts helps them fit tightly and snugly into the grooves of a sheave, giving them additional surface contact and increased stability.

When there is belt tension, vertical forces perpendicular to the top of a V-belt push its walls against the grooves of the sheave. As the forces increase, the belt wedges tightly into the sheave grooves, which increases the friction between the surfaces of the belt and the sheave walls. The ever-growing connection allows for a higher torque to be transmitted, while the increased friction minimizes the loss of power through slippage.

The multiple frictional forces allow a drive to transmit higher loads. The performance of a V-belt is determined by how tightly it fits into the groove of the sheave when placed under higher tension.