Sprockets

A sprocket is a very popular and common gear or wheel that comes with a metal teeth which meshes perfectly with a chain or track. The term pitch is used to refer to the distance between two sprockets.

Sprockets today are made in a variety of sizes. Sprockets are available in metric and also in English measurements. Sprockets do not allow gears to slip away and are specifically applied in cases where chains get engaged by gears or wheels and also in cases of motors producing rotational motions. Sprockets are essentially part of the chain drives. It is important in a chain drive that the sprocket should match with the type of chain used. Interestingly, though Sprockets look like gears but it differs in few ways from Gears:

Sprockets usually have more engaging teeth than the gears that has one or two.
In sprockets, there is no slippage of teeth. Whereas in gears, the teeth often touch and slip against each other.
There is also a variation in terms of the shape of teeth.

Types of Sprockets
Sprockets are available in a variety of styles and types. This page would highlight some of the more popular types and the classifications.
Manufacturers of sprockets in America have adopted 4 types of specific sprocket making styles as a typical American Standard. They are the following:

Type A – This is a Flat sprocket that has no hub extension on either side.
Type B – A Sprocket that has a hub extension on one side.
Type C – Sprockets that have hub extension on both the sides.
Type D – Sprockets that comes with a detachable bolt on a hub connected to a plate.

Multiple Strand Sprockets
These are another set of classification for Sprocket gears obviously based on the number of strands. Examples are:

Quick Detachable (QD) Sprocket - In this type a tapered bushing is typically bolted into the bore that is machined in the sprocket. A tight grip is provided as the bushing is inserted into the sprocket, which compresses onto the shaft.

Taper bushed Sprocket (TB) - Taper bushed sprocket (TB) is an interchangeable bushed sprocket, it gives a positive grip on the driven shaft.

Split Type Sprocket - Split Type Sprocket is a good alternative for solid type, this allows quick installation without in any way hampering the shaft and alignment.

Shear Pin Sprocket - Here a hub of the type shear pin is typically bolted to a sprocket. As sprocket torque rating increases the shear device gets the sprocket disengaged from drive.

Sprockets Based on Locking Principle to the Shaft
Based on this type of classification there can be three types of sprockets:

Bored and Keyed Sprockets - In this type, the sprockets should be mounted onto a shaft with an identical keyway to perfectly fit the sprocket.
Pilot Bore Sprockets - Pilot Bore Sprockets are available to the end users to re bore them to their own specification and need.

Application of Sprockets
There are many uses of Sprockets, some of them are highlighted below.

Farm implements - As used in a seed-cum-fertilizer drill.
Automobile applications - In two wheeler scooters, sprocket is typically a wheel that has metal teeth. The chain rides upon it. Sprockets are imperative for a smooth mobility of two wheelers.
Bicycles - A very popular application in the bicycle sector. Typically in a bicycle there are two sets of sprockets. The front sprocket and the rear sprocket. Often they are also known as the Driving sprocket and the driven sprocket. The following image clearly shows the working of sprockets in a bicycle.
Films - Sprockets find extensive are used in the film transport mechanisms of movie projectors and movie cameras. In this case, the sprocket wheels engage film perforations in the film stock.