What is a Timing Chain? What Does It Do? and How its Different from Timing Belt

Timing chain is an integral part of an internal combustion engine ( IC engine). They work to deliver a synchronize rotation motion between engine crank shaft and engine camshaft.

This article is brief introduction of timing chain, what doe timing chain do and how its different from timing belt (timing chain vs timing belt) 

To Know about Timing Chain Cost, Replacement read our article on Timing Chain life, Cost and Replacement and To learn about timing chain kit or bad timing belt symptom read our article on What is Timing Chain Kit and Bad Timing Chain Symptoms

timing chain on car engine
Timing Chain on Internal Combustion Engine

What is a Timing Chain?

A timing chain is used to connect the crankshaft and camshaft with each other to monitor the engine timing. Engine timing refers to the upward and downward movement of the pistons and opening and closing of the fuel inlet and gasses exhaust valves. 

A timing chain is enclosed within the engine and it is lubricated with the engine oil inside the engine. 

Both crankshaft and camshaft usually have sprockets attached at their one end and a timing chain is wrapped across the sprockets to connect them with each other. 

Types of timing chains

There are different types of timing chains which are categorized according to their design. 

The types of timing chains are roller chains, bush chains and toothed chains. Roller chains are further categorized into single roller chain and double roller chain. 

Single roller chain is much like a chain of a bicycle whereas double roller chain have dual gears with a chain row on each gear. Roller chains are the most famous and widely used type of timing chains. 

Roller chains have higher strength, reduced friction, less wear and give better noise and vibration performance. Double roller chains are more durable, long lasting are ideal for performance applications. 

Bush chains are used in heavy and high speed diesel engines whereas toothed chains are not used for heavy duty engines and are also known as silent chains. 

There is also a fourth type of timing chain which is a combination of toothed chain and sleeve chain to enhance the power transmission performance of toothed chain. 

What Does a Timing Chain Do?

Proper combustion is extremely important for the normal and efficient working of an engine. 

Several other factors such as fuel quality, engine temperature and number of power strokes etc. play a vital role in the combustion phenomenon. 

But, the timely opening and closing of exhaust and inlet valves are of extreme importance in enriching the combustion quality. 

In an internal combustion engine, the power generated during the combustion stroke is received at the crankshaft which runs the camshaft. 

The purpose of camshaft is to operate the valves at the suitable rate and this is done by mechanical transmission. 

A timing chain serves this purpose and it is an engine’s component that is used to synchronize the motion of camshaft and crankshaft for the proper and timely opening and closing of the engine’s valves. 

The valves allow appropriate amount of fuel and exhaust gases to enter and leave the engine’s cylinders respectively to produce the required amount of combustion at a specific speed. 

In many vehicles, fuel pump, oil pump and distributor are indirectly being drive by the timing chain. Hence, a sloppy chain can affect the overall performance of the vehicle. 

Furthermore, a timing chain also serves the purpose of a damper i.e. it absorbs the vibrations of crankshaft before transmitting the power to camshaft.

Timing Belt vs Timing Chain

Timing chain at the same time are very much like timing belt when we consider their working. But are totally different when we consider their design, material, life and other aspects. 

So follow is a brief comparison or different between timing chain and timing belt (timing belt vs timing chain)

  • Timing belt and timing chain serve a similar purpose in an engine. But there are few factors that separate them as two different choices in the context of engine’s performance.
  • A timing belt is a toothed or grooved belt manufactured from high quality rubber that is enclosed within a protective cover and runs outside of the engine whereas a timing chain is made of metal that runs inside the engine and needs to be lubricated continuously.
  • Like timing chains, timing belts are also of different types depending upon the shape of their groove. Trapezoidal belts, curvilinear belts and modified curvilinear belts are the common types of timing belts.
  • The working life of a timing belt is comparatively lesser than that of a timing chain. A timing belt is usually replaced after 60,000 and 100,000 miles whereas a timing chain needs to be replaced after 80000 to 120000 miles. 
  • Timing chain has higher strength and enhanced wear resistance as compared to the timing belts due to its material. Furthermore, timing chain is not easily susceptible to the physical changes with the change in working temperature or pressure etc. as compared to timing belt. 
  • Timing chain is usually preferred in high mileage vehicles over timing belt due to its strength and longevity of its working life. Mostly, a timing chain will last the life equal to the life of the engine but in many cases it might need to be replaced. Furthermore, timing chain has comparatively lesser problems that develop it in over the time of its usage.
  • The timing chain has the ability to damp the vibrations being induced from the crankshaft and can be used in high power applications whereas timing belt can be efficiently used for low power applications.
  • One of the major advantages of timing chain is that it does not slip during the transmission of power from camshaft to crankshaft but timing belt slippage is a common problem in timing belt drive. 
  • An advantage of timing belt over timing chain is that it does not need to be continuously lubricated and it has a silent operation. On the other hand, if the timing chain is not being lubricated appropriately, it will wear out quickly. The operation of the timing chain is a bit noisier than that of timing belt. 
  • The timing chains are heavy as they are made of metals as compared to timing belt which in turn decreases the fuel efficiency of the engine that utilize timing chain.

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