Conveyor sprockets (mill sprockets, engineering class sprockets, engineered sprockets) are used in conjunction with conveyor chains or conveyor belts. They are toothed gears or profiled wheels that mesh with a conveyor chain or belt to transmit rotary motion. Single, double, triple, quadruple and quintuple conveyor sprockets are commonly available. Dimensional specifications for conveyor sprockets include number of teeth, bore diameter, hub diameter, outside diameter, length-through bore and weight. Material selection is dependent on power-transmission and speed, environmental factors such as operating temperature and exposure to corrosive elements, and considerations such as noise generation. All-plastic hubs are relatively quiet, but suitable only for light to medium duty applications. Conveyor sprockets with hubs made of steel, stainless steel, or hardened steel are also available.
Conveyor sprockets use four types of standard hubs and two types of specialty hubs. Standard hubs are designated as Type A, Type B, Type C, and Type D. Specialty hubs have either tapered bushings or a shear-pin design. Type A devices are hubless conveyor sprockets that are designed for attachment via interference press or adhesive attachment. With Type B devices, the hub projects from only one side of the conveyor sprocket. By contrast, Type C hubs project from both sides of the sprocket. Type D products have a detachable bolt-on hub that is suitable for frequent sprocket changes or maintenance. With regard to specialty hubs, tapered bushings are tightened down on to the shaft like a collet to minimize shaft marring. Shear pin hubs provide protection against system jamming or overload. Torque is carried by shear pin, which is necked to shear when safe load is exceeded.
Metric conveyor sprockets are categorized according to ISO Standard 606 from the International Standards Organization (ISO). The number given correlates to pitch in 1/16" increments, but is expressed in millimeters (mm). For example, an ISO 12 sprocket has a 19.05 pitch and mates with a 3/4” chain. Choices for ISO pitch include ISO 04 (6.35 mm), ISO 06 (9.525 mm), ISO 08 (12.70 mm), ISO 10 (15.875), ISO 12 (19.05 mm), ISO 16 (25.40 mm), ISO 20 (31.75 mm), ISO 24 (38.10 mm), ISO 28 (44.45 mm), ISO 32 (50.80 mm), ISO 36 (57.15 mm), ISO 40 (63.50 mm). Miniature, subminiature, and conveyor sprockets larger than 63.50 mm are also available.