V-Belt Construction

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An entire v-belt can be regarded as a composite material composed of different types of rubber and reinforcements. In its usual application, a v-belt is subjected to combined tensile and compressive stresses. The top side of a v-belt is subjected to a tensile force directed longitudinally, while the bottom side is compressed due to the compression against the grooves and bending as a belt segment passes the pulley. Moreover, a different type of material is also needed at the surface of the belt. Ideal material for the surface must have a high coefficient of friction and increased wear resistance.


V-belts are generally composed of the following parts.

Fabric Cover: This part of the v-belt has higher abrasion and contamination resistance. The cover protects the internals of the v-belt from harmful external effects such as a chemical attack, corrosion, and temperature. The materials used for covers are patented by different manufacturers. An example of these materials is aramid or Kevlar fiber.

Tension Cord or Member: Tension cords are embedded into the rubber compound creating a composite structure. The tension cord or member is the main power transmitting component. The cords are positioned at the pitch diameter of the belt cross-section to increase its tensile strength. The tension cord is usually made of polyester, steel, or aramid fibers. In some v-belt constructions, the tension cord is bonded into the core by an adhesion rubber.

Elastomer Core: The elastomer core holds the components together and gives the v-belt its trapezium cross-section. This is usually made from an elastomer with good shock resistance, high flexural strength, and excellent temperature stability. Common elastomers used are neoprene, EPDM, and polyurethane. In some designs, the elastomer core is divided into two sections separated by the tension cord. Above the tension cord is the top cushion rubber while below is the compression rubber. These two sections are made from different types of rubber because of the distinct type of stresses experienced.