Buy sprockets online now at Cromwell.co.uk. We stock Simplex, Duplex and Triplex sprocket types in a range of sizes and bore types to suit your needs. Choose sprockets from reliable brands, like Dunlop BTL®, Challenge Power Transmission® and Medway®.

What are sprockets?

Also known as a sprocket wheel or chain wheel, a sprocket looks similar to a cog from the top with profiled edges or teeth around the edge. Typically made from cast iron or steel for strength; they're designed to work in conjunction with a chain and are allocated a chain reference number to identify which chain type their design corresponds to.

Why buy sprockets?

Where gears aren't suitable, a sprocket is a good alternative to deliver rotary motion using a chain and dual shaft mechanism.

When are sprockets used?

Sprockets form an important part of machines and vehicles which depend on rotary motion, like bicycles, conveyor belts, and farming machinery.

Sprocket types

Sprockets are available in three basic types, simplex, duplex, and triplex. They use this naming convention to identify the form of the sprocket and the number of teeth. Simplex has a single layer of teeth, duplex, a double layer, and triplex a triple layer. All types have corresponding chains which use the same naming convention.

Once you understand the different sprocket types, the next step is to look at sprocket bore types:

Bored and keyed sprockets   -   This type of sprocket is pre-bored with a keyway already cut. It must be mounted onto a shaft of the same size and with a similar keyway shape.

Pilot bore sprockets   -   These sprockets already have a pilot bore which can be resized to suit the shaft size. They're fitted to the shaft using a bushing to ensure a secure fitting.

Tapered bush sprockets   -   Sometimes called a taper lock sprocket, these components are fitted to a shaft using a taper bush to lock it into place.

Considerations when choosing sprockets

Bore type - choosing the bore type you require is a good starting point when looking to purchase a sprocket. Take a look at our guide above to help you identify the best type for you.

Chain reference number - this is a quick go-to to help you identify the compatible chain for the sprocket without having to measure the height of and distance between the teeth.

Taper bush number - similar to the chain reference number, the taper bush number will help you to identify the correct tapered lock bush size for your sprocket and shaft.


What's the difference between chain drives and belt drives?

While they perform a similar task, chain drives (a chain and sprocket system) drive at a lower speed with a high torque range when compared to belt drives, which are almost entirely the opposite.

How does a sprocket work?

Sprockets operate in pairs. Once mounted on a shaft, a chain is attached around each sprocket to connect the two and is held in place by the sprocket teeth. This creates a chain drive, where one sprocket must be the leader or driver while the other maintains the chain rotation and follows the lead sprocket.

Motion from the shaft will activate the chain drive which will relay power to the system and be responsible for the changes in speed and torque.