Chain Drive - Chains Versus Belts

Chains Versus Belts

Roller chain and sprockets is a very efficient method of power transmission compared to belts, with far less frictional loss.

Although chains can be made stronger than belts, their greater mass increases drive train inertia.

Drive chains are most often made of metal, while belts are often rubber, plastic, or other substances. Drive belts can slip unless they have teeth) which means that the output side may not rotate at a precise speed, and some work gets lost to the friction of the belt against its rollers. Teeth on toothed drive belts generally wear faster than links on chains, but wear on rubber or plastic belts and their teeth is often easier to observe.

Conventional roller chain drives suffer the potential for vibration, as the effective radius of action in a chain and sprocket combination constantly changes during revolution. If the chain moves at constant speed, then the shafts must accelerate and decelerate constantly. If a drive sprocket rotates at constant RPM, then the chain (and probably the driven sprocket) must accelerate and decelerate constantly. This is usually not an issue with many drive systems, however most motorcycles are fitted with a rubber bushed rear wheel hub to virtually eliminate this vibration issue. Toothed belt drives are designed to avoid this issue by operating at a constant pitch radius.

Chains are often narrower than belts, and this can make it easier to shift them to larger or smaller gears in order to vary the gear ratio. Multi-speed bicycles with derailleurs make use of this. Also, the more positive meshing of a chain can make it easier to build gears that can increase or shrink in diameter, again altering the gear ratio.

Both can be used to move objects by attaching pockets, buckets, or frames to them; chains are often used to move things vertically by holding them in frames, as in industrial toasters, while belts are good at moving things horizontally in the form of conveyor belts. It is not unusual for the systems to be used in combination; for example the rollers that drive conveyor belts are themselves often driven by drive chains.

Drive shafts are another common method used to move mechanical power around that is sometimes evaluated in comparison to chain drive; in particular shaft drive versus chain drive is a key design decision for most motorcycles. Drive shafts tend to be tougher and more reliable than chain drive, but the bevel gears have far more friction than a chain. For this reason virtually all high performance motorcycles use chain drive, with shaft driven arrangements generally used for non-sporting machines. Toothed belt drives are used for some motorcycles.