Introduction:
Belt drives are used to transmit power from one shaft to another shaft i.e. from driver to driven.
Mechanism of Belt drives:
Pulleys are mounted on the shafts for transmitting power. Belt is mounted on the pulleys without slip. Motion is then given to the driving pulley by using prime mover (like motor). Driving Pulley rotates and motion is transferred to driven pulley by belt. Belt tension is the important quantity which assures transmission without slip. Number of times belt tension is adjustable to maintain constant velocity ratio.
Following three types of sections are observed in the belt:
1. Inner face - in compression.
2. Outer face - in tension.
3. Neutral section line.
This parameters will decide the effective radius of pulley.
Types of Belt:
Basically, belts are of four types.
1. Flat Belt:
Belt with rectangular in cross-section is known as flat belt. These belts are used on slightly crowned pulleys. These belts are having joint with no upper limit for center distance between two shafts.
2. Round Belt/Rope:
Rope drives are preferred for long center distance between shafts. The most important advantage is the low cost of rope/round belt. They are of circular cross-section with joint. Also there is no upper limit for distance between two centers of rope drive. Size range of rope diameter is 3 to 20 mm. Grooved pulleys are required for round belt drive.
3. Vee Belt:
Belt with trapezoidal section is known as V- belt. The grooved pulley of a V- belt is made deeper to take advantage of wedge action. They transmit more power without slip as compared to flat belt. The height of trapezoidal cross-section is ranging between 8 to 19 mm. They are used for limited center distance because their weight/unit length is more and hence belt deflects.
4. Timing belt:
Timing belts are need toothed wheels c sprockets. They are used for achieving positive belt drive. But the center distance between two pulleys is limited when timing belts are used.
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