Attività

What is a V-Belt?

A Wrapped Type V- Belt Machine is a flexible machine element used to transmit power between a set of grooved pulleys or sheaves. They are characterized as belts having a trapezium cross-section. V-belts are the most widely used belt drives since their geometry causes them to wedge tightly into the groove as the tension is increased. As the belt wedges into the groove, friction between the surface of the belt is increased, allowing high torques to be transmitted. The increased friction minimizes the loss of power through slippage.

Overview of Belt Drives

Before going deeper into v-belts, it is important to know an overview of belt drives. Belt drives are machine elements that are used to transmit power between two or more rotating shafts, usually with parallel axes of rotation. The belts are looped over pulleys attached to the driver and follower shafts. These pulleys are placed at a certain distance to create an initial tension on the belt. When in operation, the friction causes the belt to grip onto the pulley. The rotation of the driver pulley increases the tension on one side of the belt creating a tight side. This tight side applies a tangential force to the follower pulley. Torque is then applied to the driven shaft. Opposite the tight side is the slack side where the belt experiences less tension.

There are many types of belt drives used today. The earliest type of belt drive uses a flat belt made from leather or fabric. Flat belts operate satisfactorily in low-power applications such as farm equipment, mining, and logging. At higher loads and speeds, they tend to slip on the surface of the pulleys and climb out of the pulley. Another early type of belt drive is a rope drive made from cotton or hemp. Rope drives are used on two pulleys with a V-shaped groove. This solved the problem of climbing out of the pulley enabling belt drives to be used over large distances. Later, this was developed into round beltswhich are made from elastomeric materials such as rubber, nylon, or urethane. The development of these elastomeric materials also brought the progress of belt drive technology. Belts such as v-belts, ribbed belts, multi-groove belts, and timing beltswere made to solve the problems of previous belt drives.

V-Belt Construction

An entire Classic V-belt Machine 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.

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