GearBoxGears and sprockets; sprockets and gears… We use them every day in dozens of applications without even thinking about them, let alone thinking about what the differences are.

If you have ever wondered what the difference between a sprocket and a gear is, now’s your chance to find out.

Both sprockets and gears are grooved wheels that operate within a machine, but their functions are rather different. Gears are generally toothed wheels that connect with the teeth on other gears to transmit movement to another part. Sprockets use their teeth to interact with and move one (sometimes more) flexible component, like a bicycle chain or a conveyor belt.

The basic principle is similar

Gears tend to interact with other gears to transmit power (often the component to be moved is larger than one gear alone can move) to the “end-user”, as it were. Sprockets interact directly with the end-user by moving it along. Sprockets can work alone, but gears need to form a network to control the amount of power transmitted to the moving part.

It’s all in the teeth

The biggest physical difference between a sprocket and a gear can be seen in the teeth. In bike chain sprockets, for example, the teeth have to be shaped so that they fit perfectly into the indentations, holes or slots in the object they are intended to move.

Gears interact with one another, so the design of the teeth can be varied. The teeth may be on the inner side of the wheel, for example, if this saves a bit of space.
More sensitive to damage

Sprockets are also more affected by damage. Think about the two sprockets that move and guide that bicycle chain. If one or two of the teeth are broken or damaged, there’s much more chance of the chain coming loose or slipping to the side. If a gear loses a tooth or two, a small amount of power may be lost, but the gears will continue to turn and work.

Uses for sprockets

Sprockets aren’t just found supporting bike chains, they also do their thing in bulldozer and tank tracks, as well as in film projectors. The sprockets in all of these machines rotate to move a flexible belt of some kind – a bike chain or a conveyor belt – and the many moving parts of these belts means more wear and tear on the belt itself and the sprockets. This is why sprockets tend to be placed on the outside of the machine so that they can be fixed or replaced with ease.

Uses for gears
Gears tend to be placed more deeply inside machines – transferring power from a car engine to the drivetrain, or moving the hands on a clock or watch. Gears are more resistant to damage and are more efficient than sprockets (which is not to say that sprockets don’t perform well where they are used!), so engineers and developers prefer to use gears. A good example of this is when car designers started to use rigid drivetrains and gears to move cars along – previously, many cars were using chain drives, but the last chain-driven cars were made in the 1960s.

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