Question

why is disesel used as a fuel in heavy vehicle?

Answer 1

for a given power, they produce higher torque at low speeds, which is the primary requirement of aheavy engine. ii. Diesel engines employ higher compression ratios; so the peak pressures and temperatures reached are higher as compared to petrol engines, which in turn requires the engines to beheavy and robust.

Answer 2

Diesel engines produce better torque than petrol engines.

Now, why torque is required in heavy vehicles?

Torque is the rotational force transmitted to the crankshaft. In other words, higher rotational force helps in pulling heavy loads. The biggest haul trucks used in mining industries are equipped with V20 diesel engines to provide better torque to carry heavy loads with proper acceleration.

Diesel burns gradually due to its fuel property of being non-volatile, unlike petrol which is volatile. Gradual burning helps in transmitting better torque and get better fuel efficiency.

Stroke length of diesel engines are also higher than in petrol engines, even that helps in producing better torque.

The initial gear ratios of heavy vehicles are around 5:1 to 6:1 which is one of the reasons why trucks and heavy vehicles are able to produce high torque.