timing belt

Everything you need to know about timing belt or chain

Two engine components are interconnected with a timing belt, which is also known as a timing chain, or cambelt. The part synchronizes the rotation of an engine crankshaft and camshaft in order to open and close the engine’s valve at the proper timing to ensure unobstructed combustion. Now you can see the essence of a timing belt in the engine combustion process since the valve opens and closes for the intake of air/fuel mixture and escape of exhaust gas

The model of a vehicle determines whether a timing belt or chain is used. the chain might be used instead of a drive belt, but they still serve the same purpose. The reason why the timing belt is widely used is that it’s lighter and quieter ever since it was introduced in the 1960s. However, modern engines now work with timing chains as they can serve for a long period of time.

timing belt

Today we’ll be looking at the definition, functions, parts, diagram, types, and working principle of a timing belt. I’ll also explain the construction and design as well as the symptoms of a bad-timing belt.


Timing Belt Definition

A timing belt is a component used in an internal combustion engine to synchronise the movement of the crankshaft and camshafts. It is designed with a precise hard tooth that interlocks with the cogwheel of a crankshaft and the two camshafts. Because of the accurate teeth of a drive belt, the intake and exhaust valves open and close in time with the pistons.

The construction and design of a timing belt is typically a rubber with high tensile fibres. The entire belt is constructed in sturdy material such as moulded polyurethane, neoprene or welded urethane of various levels. the tooth may be non-standard or metric pitches. A pitch is the distance between the centres of two adjacent on the timing belt.

Rubbers degrade with higher temperatures and then come into contact with oil. Timing belt lifespan is reduced in hot and oil-leaky engines. Though newer and more expensive belts are made of temperature-resistant materials such as “highly saturated nitrile”. Also, water or antifreeze can greatly affect the life of the reinforcing cords, making the need for special precautions for off-road applications. This is why most engines are highly in the seal.

Older timing belts usually experience a high rate of wear due to their trapezoid-shaped teeth. Well, most manufacturers employ newer techniques by making the teeth curve which makes it quieter and lasts longer.

Functions of Timing Belts

Below are the functions of timing belts or chains in automotive engines:

  • The timing belt allows the achievement of the combustion process as the control of the piston and valves relies on it.
  • It connects the crankshaft and the camshaft together to control the valve operation.
  • The timing belt ensures precise synchronised opening and closing of the engine’s valves.
  • Some other engine components such as water pump, injection pump, and oil pump.
  • The timing belt uses the same combustion mechanical energy to control the valve. This means no external source is included.
  • Another function of a timing belt or chain is that it prevents the piston from striking the valves on a critical level.

A timing belt is just a single device but connects different parts such as the camshaft sprocket, timing belt idler pulley, upper balance shaft sprocket, water pump pulley, timing belt tensional roller, balance idler roller, lower balance shaft sprocket, camshaft belt drive gear, balance belt drive gear, and balance belt tensioner roller.

The timing belt diagram below gives more detail:

timing belt components

Types of Timing Belt

There is a lot to be considered when stating the types of timing belts as they can be determined by the following explained below:

  • Pitch selection
  • Pulley selection
  • Pulley drawing
  • Belt selecting
  • Shaft selecting
  • Design assembly
  • Metric Dimensions Timing Belt
  • Trapezoidal tooth shape with metric dimension.
  • Round tooth shape with metric dimension.

Imperial Dimensions Timing Belts


All these must be considered before listing the types of timing belts but most vehicle manufacturers have a standard design for a specific model of vehicle. but you can watch the below video to learn more about the timing belt or chain types.

Working principle

timing belt side view

timing belts do their work in a precise and timely manner. It is the reason why the engine’s combustion process is possible even though the power to rotate the crankshaft. it then synchronizes the camshafts which allow the valve to open and close so that the intake of air and fuel can enter the combustion chamber. The exhaust valve is also controlled by this rotation so that the exhaust can escape. this process is done in harmony.

As the camshaft and crankshaft work in coordination, crankshafts are designed to operate at half the speed of the camshaft. For instance, two turns of the crankshaft result in a turn of the camshaft. The timing belt requires tension to properly operate, which is why the timing belt tensional is designed.

Modern vehicles use automatic timing belt tensioners that do not require adjustment. The older vehicles would always need adjustment from time to time as the belt becomes loose. A loose timing belt will force the timing out of range, which is why the problem should be avoided. Timing is so important that if one movement escapes, it can affect the efficiency of the engine leading to loss of power, misfires etc.

Related Article:

Watch the video to understand the workings of the timing belt or chain better:


In conclusion, timing belts are rubber components with tension that help the rotation of a variety of components in an engine. The work is precise, as the valve makes use of it in such a manner. It connects the crankshaft and camshaft together; the crankshaft receives power from the piston which is attached to a connecting rod. In this article, we saw the functions, working, and types of timing belts or chains. I hope you enjoyed the reading, if so, kindly comment, share and recommend this site to other technical students. Thanks!


2 responses to “Everything you need to know about timing belt or chain”

  1. Great post! As a student, it’s really helpful to understand the concept of timing belts and their functions. The diagram you provided is easy to follow and helps me visualize how it works. Thank you for sharing this informative post!

  2. Great post! I learned a lot about timing belts and their importance in an engine’s performance. The diagram and working explanation were very helpful in understanding how it all fits together. Thanks for sharing this informative post!

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