Everything you need to know about timing belt or chain

Two engine components are interconnected with a timing belt, which is also known as 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 proper timing to ensure unobstructed combustion. Now you can see the essence of a timing belt in the engine combustion process, since valve open and close for the intake of air/fuel mixture and escape of exhaust gas.

The timing belt is made of rubber with hard teeth that key with the cogwheels of the crankshaft and the camshafts. The component sometimes powers the oil pump, water pump, and injection pump depending on the engine design. Timing belts are referred to a toothed belt or a drive belt designed with teeth on the inside surface. While a timing chain is a roller chain but the manufacturer use either of them to achieve the same purpose.

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The model of a vehicle determines either a timing belt or chain is used. the chain might be used instead of a drive belt, 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’s 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 symptoms of a bad timing belt.

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Timing Belt Definition

A timing belt is a component used in an internal combustion engine to synchronizes 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 level. the tooth may be non-standard or metric pitches. A pitch is a distance between the centres of two adjacent on the timing belt.

Rubbers degrade with higher temperatures, and when come to contact with oil. Timing belt lifespan is reduced in hot and oil leaky engines. Though newer and 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 chain 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.
  • Timing belt ensures precise synchronize 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.

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Timing belt diagram below gives more detail:

timing belt components

timing belt side view

Types of Timing Belt

There is a lot to be considered when stating the types of a timing belt as they can be determined by the following explain 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.

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Working principle

timing belts do their working in a precise and timing manner. It is the reason why the engines 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.

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As the camshaft and crankshaft work in coordination, crankshafts are designed to operate half the speed of the camshaft. For instance, two turns of the crankshaft result to a turn of the camshaft. The timing belt requires tension to properly operate, which is why timing belt tensional is design. 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 escape, it can affect the efficiency of the engine leading to loss of power, misfires etc.

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

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Symptoms of a bad or failing timing belt or chain

Below are the symptoms of a bad timing belt or chain that need replacement:

  • Engine power is decreased
  • Engine overheating
  • Trouble starting the engine
  • Vibrating or shaking of the engine
  • Oil leakage
  • Ticking noise from the engine
  • Engine light on
  • Engine misfiring
  • Squealing or rubbing noises from the belts.

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In conclusion, timing belts is a rubber component with tension that help the rotation of a variety of component in an engine. The work in a precisely, as the valve make use of it in such manner. It connects the crankshaft and camshaft together; the crankshaft receives power from the piston which attached to a connecting rod. In this article, we saw the functions, working, and types of timing belts or chains.

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