The most common systems for transmitting power from a drive to a driven shaft are V belt, gear, and chain drives. But V belt drive systems, also called friction drives (because power is transmitted as a result of the V belt’s adherence to the pulley) are an economical option for industrial, automotive, commercial, agricultural, and home appliance applications.

The most common systems for transmitting power from a drive to a driven shaft are V belt, gear, and chain drives. But V belt drive systems, also called friction drives (because power is transmitted as a result of the V belt’s adherence to the pulley) are an economical option for industrial, automotive, commercial, agricultural, and home appliance applications. V belt drives are also easy to install, require no lubrication, and dampen shock load.

Pulleys with more tracks pull more load

Here’s the catch: Standard friction drives can both slip and creep, resulting in inexact velocity ratios or degraded timing precision between input and output shafts. For this reason, it is important to select a V belt appropriate for the application at hand.

V belt makeup

V belt drives are one of the earliest power transmission systems and were widely used during the Industrial Revolution. Then, flat belts conveyed power over large distances and were made from leather. Later, demands for more powerful machinery, and the growth of large markets such as the automobile industry spurred new belt designs. V belts, with a trapezoidal or V shape, made of rubber, neoprene, and urethane synthetic materials, replaced flat belts. Now, the increased overall surface material of modern V belts adheres to pulley grooves through friction force, to reduce the tension required to transmit torque. The top part of the V belt, called the tension or insulation section, contains fiber cords for increased strength as it carries the load of traction force. It helps hold tension members in place and acts as a binder for greater adhesion between cords and other sections. In this manner, heat build-up is reduced, extending V belt life. Prestretched tension-member cords (polyester, aramide, steel, fiberglass) also minimize stretch.

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