Power transmission in machinery often employs either flexible belts or rigid chains. A belt system uses a continuous loop of flexible material stretched between pulleys to transfer rotational motion. This contrasts with a chain system, which uses interlinked rigid elements engaged with toothed sprockets. A bicycle offers a familiar example of chain-driven power transmission, while many automotive engines utilize belts to drive accessories like alternators and water pumps.
Choosing the appropriate method is critical for optimal performance, efficiency, and longevity. Historically, belts predate chains and continue to be favored for their quieter operation and simpler maintenance. Chains, developed later, offer higher power transmission capacity and maintain a precise speed ratio due to their non-slip nature, essential in applications requiring synchronization. The specific requirements of an application dictate the best choice.