In an industrial facility, motors and turbines use energy to produce rotational mechanical motion. In order to harness this motion to perform useful work, there must be a way to transmit it to other components and machines. Three common methods of accomplishing this include gear drives, chain drives, and belt drives.
Gears
Gears are rolling cylinders, or cones, that have teeth on their contact surfaces. The teeth of two or more gears mate together to transmit power positively from one shaft to another. They can be used to change the direction of rotation of a power transmission system, or they may be used to increase or decrease the speed of the driven shaft, thus decreasing or increasing the torque.
Gearboxes, gear sets, and gear trains are all terms that describe a collection of gears and supporting components used to transmit power from a rotating source to another device or devices in a machine. The gears can be used to change the speed, torque, and direction of the rotational power, or simply transmit it over a distance in a 1 to 1 ratio.
Chain Drives
Chain drives consist of an endless series of chain links, which mesh with toothed sprockets. Chain drives are used to transmit power from one component to another. Specifically, they transfer speed and torque through the use of a linked chain and sprockets. Chain drives are well suited for this task because the sprocket teeth and chain setup results in a positive speed ratio and the ability to transfer a large amount of torque within a compact space.
Standard roller chains are made up of evenly spaced, repeating inner and outer roller links. Each inner link is made up of two link plates, two bushings, and two rollers. The outer links are composed of two link plates and two pins, which are usually riveted and rotate freely in the link plate holes. The outer link pins pass through the hollow inner link bushings, allowing the two types of links to join together.
As the chain moves around a sprocket, the rollers will rotate around the bushing, allowing the links to bend and wrap around the sprocket. Because the rollers rotate against the bushing and not the sprocket, the chain and sprocket teeth experience much less wear, extending the lifespan of the components.
Belt Drives
Belt drives are used to transmit power from a pulley to one or more other pulleys, and are popular due to their cost effectiveness and relative simplicity. Belt drives for power transmission are classified as frictional drives since the belt transmits power via friction between the belt and the driving and driven pulleys.
Selection
When selecting a mechanical transmission system, several considerations must be taken into account to ensure proper operation, long service life, and low maintenance requirements. Environmental factors, such as exposure to certain liquids, operating temperatures, contamination, and weather conditions must be weighed. System requirements are also crucial to selecting the appropriate system, including RPM, horsepower requirement, distances, space limitations, and load conditions.