Chains and Belts: Power Transmission Explained

Chains

Drawbacks of Chains

A drawback of chains is the production of vibrations during operation.

Chain Rollers

Chains consist of inner and outer plates. Pins connect these plates. The outer plates are thicker than the inner plates, with larger holes. Rollers rotate freely on the pins, minimizing friction between the chain and the sprockets.

Chain Cassettes

Cassettes are similar to rollers but without the rolling action. They are more economical and suitable for short chains with light loads.

Chain Blocks

Block chains are designed for heavy loads. They consist of outer plates, pins, and solid blocks between consecutive links.

Chain Links

Links are angled plates that serve as both outer and inner plates. The advantage is the adjustability of chain length by removing individual links.

Chains require proper tension. During operation, the section between the drive and driven sprockets should be taut, while the return side should be slightly loose. Tension is adjusted by moving one of the sprockets. Once the movable sprocket reaches its limit, two links should be removed from the chain.

For longer distances, tension is maintained using idler sprockets, which can be internal or external.

Advantages of Chains

• Minimal load on the axles.
• Compact size.
• Even wear distribution on sprockets.
• Easy to cut and join.

Disadvantages of Chains

• Can be noisy.
• Require maintenance and lubrication.

Belts

Belts transmit power between typically parallel shafts where precise transmission ratios aren't critical. Elastic slip between the belt and pulleys causes variations in the transmission ratio, depending on torque and speed.

Advantages of Belts

• Can connect shafts over long distances.
• Relatively smooth, quiet operation.
• Low initial cost.

Disadvantages of Belts

• Large exterior dimensions.
• Inconsistent transmission ratio due to elastic slip.
• Relatively short lifespan.

Elastic Slip

Slippage occurs because the belt stretches under tension on the driving side. This stretching happens as the belt passes over the pulleys.

Flat Belts

Flat belts have a rectangular profile. Traditionally made of leather or textiles, they are now commonly made of synthetic rubber, sometimes reinforced with steel or engineered plastic.

Round Belts

Round belts are inexpensive, easy to install, and suitable for long lengths.

V-Belts

V-belts are the most common type. Made as a single piece, they eliminate the need for joining.

Hexagonal Belts

Hexagonal or double-V belts have a dual trapezoidal profile. They are used when the belt passes over multiple internal and external pulleys.

Ribbed Belts

Ribbed belts are like multiple V-belts joined together. They are used for high power transmission while minimizing bending losses.

Toothed Belts

Like chains, toothed belts ensure synchronization between pulleys and eliminate elastic slip.

Belt Tension

Proper tension is crucial to prevent slippage.

Belt Maintenance

Regular inspection is necessary, with frequency depending on the machine and operating conditions.