SEED Guides Component Selection - Chain Drives < >

When choosing an appropriate transmission system, chain drives should be considered for suitability along with gears and pulley systems. Despite having features in common with other types of transmission, chain drives have significant differences also. A comparison of some of the salient characteristics of the various transmission systems is helpful, at the preliminary design selection stage, when considering whether a chain drive is the most suitable for an application.

Chain drives may be likened to pulley drives since both forms of transmission system link driving and driven shafts together causing rotation in the same direction. In the case of timing belts the resemblance is even closer since they, like chain systems, operate synchronously. Chains, though, are inherently stronger than pulley belts because they are normally made from steel rather than a rubber / nylon composite and so can support larger tensions and thus transmit greater power. Also, because links may be added or removed, it means that the need for standard chain length sizes is avoided - as is the case with pulleys. In addition, since chains do not require tension on the slack side it considerably reduces loads on bearings.

Chain drives do not enable quite as compact an arrangement to be achieved as gears, since sprockets do not engage directly together. However, chains are more flexible because they can operate with a large range of centre distances between drive and driven shafts and they more efficiently support the turning force by distributing it onto more teeth than gears. Chain drives are also more tolerant to shaft misalignment and centre location variations and are generally less expensive than gear drives.