Why do most tractors generally use diesel engines rather than petrol ones?

Petrol and diesel engines

Even those that are unfamiliar with automobiles and their workings know that engines for cars, bikes, tractors and other such vehicles generally run either on petrol or diesel. 

The working of both petrol and diesel engines differ since both these fuels work differently. The main difference between a petrol and diesel engine occurs in the way combustion occurs inside the engine

In a petrol engine, fuel is combined with air before being ignited with spark plugs. On the other hand, in a diesel engine, air is compressed beforehand and then fuel is injected to propel the car forward. 

While this is the technical difference between the two, there are also other differences with regards to torque, cost, fuel efficiency, as well as the pollution caused by the fuel. 

Costs

Diesel and petrol prices are constantly fluctuating. However, on an average, in India, diesel is generally cheaper than petrol, due to government subsidies on diesel. 

That being said, diesel cars are generally more expensive than cars that run on petrol, since a diesel engine costs more to be manufactured. 

Fuel and environment efficiency

Diesel is the preferable fuel in terms of the environment. While a lot of people believe that petrol is less polluting than diesel, this is actually incorrect. 

Studies have proven that diesel engines produce far fewer emissions than comparably-sized petrol engines. Furthermore, Diesel is aso much more fuel efficient, and can travel up to 33% more on the same amount of fuel in the tank. 

Torque

In simple terms, torque is the amount of force a rotating mechanism, such as an engine crankshaft, generates. The torque that is generated by the engine at low speeds is known as low-end torque, which is different from horsepower. 

While diesel and petrol engines may be comparable in terms of horsepower, they differ a lot in terms of low-end torque.  

A diesel engine generates more low-end torque than a petrol one, since diesel has greater compression resistance than petrol. 

Role of torque in tractors

While differences in cost, fuel efficiency and pollution are important when comparing diesel and petrol, the difference in low-end torque is the essential factor when it comes to heavy, load bearing vehicles. 

For example, a truck is supposed to carry heavy loads over all types of terrain. Similarly, a tractor is an extremely heavy vehicle meant to work in different types of fields. 

In order for trucks, tractors and other such heavy vehicles to work optimally, the amount of low-end torque generated by an engine needs to be high, for them to have maximum power. 

Use of diesel in tractors

It is clear that due to higher resistance to compression, diesel engines produce higher low-end torque than petrol ones. This high amount of torque is necessary for large, heavy, load bearing vehicles to function optimally. 

This is the reason that most tractors use diesel engines rather than petrol ones. In India, since prices of diesel are lower, this also makes sense from an economic perspective, since tractor users can get more work done at lesser costs by using a tractor with a diesel engine. 

Conclusion

Vehicle owners must make the choice between a petrol or diesel powered vehicle based on their needs, likes and dislikes. Overall, diesel is becoming more and more popular today since it costs less, has more fuel efficiency and is also more environmentally friendly. 

However, due to the higher costs of diesel cars, it is still not affordable for all. However, when it comes to heavy machines like tractors, diesel engines are the best option, because of the higher amounts of torque they generate, which helps these large vehicles function well. 

This is why, most tractors are powered by diesel rather than petrol. 

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