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What Is a Cam Sprocket?

C.B. Fox
C.B. Fox

The cam sprocket is attached to one end of the camshaft in a combustion engine. This sprocket, along with the timing belt and the crankshaft sprocket, is responsible for maintaining the timing between the crankshaft and the camshaft. It is similar to a pulley or gear, though unlike a pulley, it has ridges along the outside, and unlike a gear, it does not come into direct contact with another sprocket.

Having teeth along the outside allows the cam sprocket to link into a chain with links that are the same size as the sprocket's teeth. The chain runs along the outside of the sprocket and connects to another sprocket, the crankshaft sprocket, which is usually located near the cam sprocket. Connected by the chain, these two sprockets are able to turn at the same pace even though they do not touch. In most vehicles, the sprocket is twice the diameter of the crankshaft sprocket, which means that for every two revolutions of the crankshaft sprocket, the cam sprocket only rotates once.

A cam sprocket is attached to a camshaft in a combustible engine to help maintain timing.
A cam sprocket is attached to a camshaft in a combustible engine to help maintain timing.

The axel of the cam sprocket is connected to the camshaft. As the sprocket turns around, it causes the camshaft to rotate as well. This rotation is timed so that the valves on the camshaft open and close in time to the rotation of the crankshaft, where linear energy is converted into rotational energy. The proper timing between the camshaft and the crankshaft allows the engine to run properly.

Any piece of machinery that uses an internal combustion engine can use a cam sprocket to help control the timing of the engine components. These devices have been in use since the 3rd century before the Common Era (B.C.E). In ancient Greece, they were used in various machines, including weaponry and toys. In modern times, these devices can be found in vehicles, including cars and trucks.

Made of a strong, study metal such as aluminum, a cam sprocket is able to function for a long time without wearing down. Though these pieces are sturdy, they often need to be replaced in cars and trucks between every 60,000 and 100,000 miles. Usually, the timing chain is replaced at the same time as the two sprockets. The eventual wear on the sprocket occurs because the timing chain can loosen over time. The process of replacing these components can be difficult and time consuming and is usually done by a trained mechanic.

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    • A cam sprocket is attached to a camshaft in a combustible engine to help maintain timing.
      By: Rob Byron
      A cam sprocket is attached to a camshaft in a combustible engine to help maintain timing.