Sprockets Made Easy

by Mildred Cahulogan.

Do you always feel intimidated whenever you look for Sprockets? Do you always feel that the information written about Sprockets are just for Engineers or too complicated to understand? In that case let us help you how you can understand sprocket in layman’s term.

First let’s define what Sprockets are.

What are Sprockets?

A toothed wheel engaging with a conveyor or power chain. Used in bicycles, motorcycles, tracked vehicles, cars and other machinery to transmit rotary motion between two shafts.

The simplest common example of how Sprockets work can be found in the bicycle. Where the pedal carries a large sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the rear wheel.

 

Uses and Applications

Sprockets have a very popular application in the bicycle sector, automobile applications, motorcycles, tracked vehicles and other machinery. They are used also as farm implements in a seed-cum-fertilizer drill.

Parts of a Sprocket

 

Number of Teeth is the total count of the number of teeth around the sprockets. To determine the number of teeth you can simply count the number of teeth.

Pitch Diameter, is an imaginary circle which is traced by the center of the chain pins when the sprocket rotates. To calculate the pitch diameter is the ratio of pitch diameter between sprockets can be used to calculate the gear ratio, or simply the ratio of the number of teeth is used for this calculations.

Pitch the amount of pitch diameter in inches per tooth.  Common pitches are 0.25”, known as #25, and 0.375” (#35).

Outside Diameter (OD) always larger than the pitch diameter but smaller than the chain clearance diameter.

 

Sprockets are characterized by type, which indicates hub style:

Hub (indicates the core of the sprocket)

Hub (indicates the core of the sprocket)

    • Type A sprockets are flat and have no hub.They are usually mounted on flanges or hubs of the device they are driving through a series of holes that are plain or tapered.

     

    • Type B sprockets have a hub on one side, allowing the sprocket to be fitted closely to the machinery on which it is mounted. This eliminates a large overhung load on the bearings of the equipment.

     

     

    • Type C sprockets are extended on both sides of the plate and usually used on the driven sprocket where the pitch diameter is larger and where there is more weight to support on the shaft. Larger loads should have larger hubs.

     

    • Type D sprockets use a type A sprocket mounted on a solid or split hub. The sprocket is split and bolted to the hub for easy removal. Speed ratio can be changed by without having to remove bearings and other equipment.

     

    Most Common Types of Sprockets

 

A Plate Sprockets:

Type A Steel Sprockets, are flat and have no hub. Usually mounted on flanges or hubs of the device they are driving through a series of holes that are plain or tapered Machine cut, single strand range from No.25 through 240.

 

 

B Type Sprockets

Type B Steel Sprockets, have a hub on one side, allowing the sprocket to be fitted closely to the machinery on which it is mounted. This eliminates a large overhung load on the bearings of the equipment Machine cut, single strand range from No. 25 through No. 240.

 

 

Double Sprockets

Similar to standard sprockets except there are half the number of teeth. They are used with small roller double pitch chain to accommodate longer distances between rollers. Double strand steel sprockets stocked in No. 35 through No. 200 for re-boring. Many sizes standard with hardened teeth

 

QD (Quick Disconnect) Sprockets

Are used where higher working loads and high clamp loading on the shaft is desirable. They are flanged and use anchor bolts around the circumference. Sprockets with tapered bushings are easy to install and remove, provide clamp force, and align the sprocket. Single strand steel sprockets – No 40 through No 160

 

Sprocket Terminology

Teeth:  The number of actual teeth on the sprocket.

Hub Type:  Indicates the core of the sprocket.

Sprocket Outside Diameter: The measurement from sprocket tooth peak to sprocket tooth peak on the opposite side.

Maximum Bore Diameter: Maximum bore size a sprocket can be machined without compromising structural integrity. Associated with B and C style sprockets.

Length Through Bore (LTB): The inside hub diameter and the length to which it was machined. The length must be able to accommodate the proper sized keyway to withstand shear and torque stress.