The Hub refers to the core of the sprocket. Each is designed for a specific need depending on the design of your drive or conveyor system.
Type A – has no hub and must be mounted on a flange, hub, or other device to hold it in place Type B – has a hub extension on only one side and is generally made on small or medium size sprockets.
Type C – has hub extensions on both sides and is generally found on large diameter sprockets
Teeth – The number of teeth on a sprocket is determined by chain pitch and size. Larger sprockets have more teeth and generally will last longer than smaller sprockets because the wearing action is distributed over a larger area. Double pitch sprockets, which have two teeth per chain pitch, also have a longer life because only half the teeth engage with the chain per revolution. An odd number of teeth will engage with the chain every other revolution basically doubling the life of the sprocket. An even number of teeth periodically advances one tooth to acquire the same result.
Bore Diameter – The bore has to be large enough to fit the shaft and at the same time maintain sufficient hub wall thickness for proper strength.
Length Thru Bore – or hub thickness must accommodate a keyway long enough to handle the shear stress from the shaft.
Pitch Diameter – This is the diameter of the pitch circle that passes through the center of the pin as the chain engages with the sprocket.
Outside Diameter – This is the measurement from the tip of one sprocket tooth directly across to the tip of that tooth.
Bottom Diameter – This is the diameter measured from the seating curve at the bottom of one sprocket tooth space directly across to the seating curve at the bottom of the corresponding tooth space.
Caliper Diameter – Sprockets with an odd number of teeth, this is measured from the seating curve at the bottom of one sprocket tooth space across to the seating curve at the bottom of the sprocket tooth space nearly opposite.
To order sprockets, request a quote, or request information, please submit a Quote Request, and a Bearing & Transmission Supply representative will contact you. For immediate help, call us at 800-621-0237.