How does a Tractor Engine work? Different Types of Tractor Engines
Table of Contents
What is the Role of Tractor Engine?
Engine is the heart of any vehicle, and tractors are no different. A tractor engine generates power, which is transmitted to PTO and wheels through the transmission system. Thus, it offers power to the tractor to perform all kinds of tasks on and off the road.
Diesel is the most common type of fuel used in tractors. This is because they have a higher compression ratio, which results in better fuel efficiency. Also, diesel engines produce higher torque, which is the basic need of a tractor. Electric tractors are the newest in the Indian market. They lack an internal combustion (IC) engine as they have an electric motor and a battery to generate power for different tasks.
What are the Different Parts of a Tractor Engine?
A tractor engine runs to deliver high torque at a low speed. It is an internal combustion engine that generally runs on diesel. So, this engine compresses and burns fuel to generate mechanical motion power. A tractor engine has a complex structure and comprises several parts. Following is the list of key parts of a tractor engine:
Cylinder
A cylinder is an important component of the engine. It is a chamber where fuel combustion takes place to generate power. More cylinders mean more pistons to combust fuel, thus producing more power. The cylinder deals with all the pressure and heat produced after fuel combustion. This is why robust materials like cast iron are used to make cylinders. Also, it needs a cooling system to handle high temperatures and ensure efficient operations.
Piston
A cylinder houses a piston that has a reciprocating motion to compress the fuel-air mixture and cause combustion. A piston generates pressure forces via fuel combustion that is transmitted to rotate the crankshaft using a connecting rod. Its top is called a crown, while the sides are known as a skirt. A piston also must withstand high temperatures and pressure. Thus, it is constructed from cast iron or aluminium alloy. Piston rings provide the sealing between the piston and cylinder.
Camshaft
This rotating shaft operates the intake and exhaust valves throughout the engine cycle. The camshaft determines the specific duration and precise timing of the valve opening/closing. So, it ensures timely intake of air, combustion of fuel and removal of exhaust gases. The camshaft allows coordinated movement of valves, which is integral to the power output, efficiency and performance of the engine.
Crankshaft
A crankshaft is simply a rotating shaft that changes the reciprocating movement of the piston into rotational motion. The connecting rod transfers the power generated to the crankshaft. The rotational motion of the crankshaft moves the flywheel to move the tractor. The materials used to make a crankshaft are cast iron or forged steel. A crankshaft is an important element of the transmission system, as any design error can result in engine failure.
Fuel Injector
A fuel injector injects fuel when the compression stroke ends after atomizing fuel into fine droplets. In an IC engine, the air is forced into the cylinder during the intake stroke. This air is then compressed to extremely high pressure. The fuel is pressurized at high pressure to get atomized. At a specific injection time, a precise amount of fuel is injected into the chamber for optimum combustion. A fuel injector ensures a good quality fuel-air mixture that provides better engine efficiency and lower emissions.
Flywheel
This mechanical device consists of a heavy disc that can store rotational energy. It offers consistent power to the crankshaft and keeps the engine running. A flywheel operates can be considered a temporary reservoir of energy. Its primary purpose is to prevent speed fluctuations in the transmission system. It makes use of the conserved rotational energy to smoothen the power delivery from the tractor engine. Also, it maintains the angular momentum of the crankshaft during the non-power strokes.
How Does a Tractor Engine Work?
As mentioned before, a tractor uses an internal combustion engine. The main principle of all IC engines is the same: air mixed with fuel in the correct proportion creates an explosive mixture. This mixture, under extreme pressure, gets ignited and generates power to move the tractor.
The engine draws air into the cylinder. This air is compressed significantly, which increases its temperature to high levels. In the next step, fuel is injected into the cylinder. Fuel combusts immediately due to the high-temperature air. This creates an explosion to generate force to move the piston and drive the crankshaft. Lastly, the crankshaft transmits the power to the wheels.
A diesel engine works through the repetition of a cycle of four strokes or stages. In a single cycle, the piston moves from the top to the bottom two times. In other words, the crankshaft of the tractor rotates twice. The operation cycle of the 4-stroke tractor engine involves the following stages:
Intake Stroke
In the intake stroke, the inlet valve opens while its piston moves down the cylinder. So, the cylinder receives air from outside. As the piston moves to the bottom, the air is filled in the cylinder. At last, the inlet valve is closed.
Compression Stroke
First, the inlet valve is closed at this stage. Both inlet and outlet valves are closed in this stroke. As the piston moves up, the air mixture gets compressed in a tight space, which heats it to high temperatures. When the compression stroke ends, fuel is injected into the cylinder. The ignition occurs spontaneously when the fuel comes in contact with pressurized and high-temperature air.
Power Stroke
Both valves still remain closed in the power stroke. Due to ignition, extreme heat is generated inside the cylinder. The piston is pushed down due to the high pressure in the cylinder. This downward movement is known as a power stroke. The generated power is transmitted from the piston to the crankshaft with the help of the connecting rod. The crankshaft begins to rotate and transfers power to the wheels.
Exhaust Stroke
The piston travels upward in this stroke. The exhaust gases move out through the exhaust valve. As the burnt gases are eliminated from the tractor engine, the cylinder can receive fresh air, and the cycle continues.
Infographics – four strokes diesel engine
What are the Different Types of Tractor Engines?
The engine is the most crucial component of a tractor as it provides the power needed to perform different farm tasks. Based on how air is drawn into the engine, the tractor engine can be categorized into two types: Naturally Aspirated and Turbocharged. Go through the next section to know which engine type is suitable for your farming needs.
Naturally Aspirated Tractor Engine
In a naturally aspirated (NA) engine, cylinders receive air with the help of atmospheric pressure alone. It means there is no external mechanism or forced induction system to force air into the cylinder. For more power in an NA engine, a larger mix of fuel and air is combusted in the engine. Thus, the manufacturer increases the number of cylinders or their bore to increase the volume of the combustion chamber and derive extra power. This is why naturally aspirated tractor engines are likely to have a larger displacement.
As NA engines have fewer components, they are more reliable, durable and easier to maintain. Their manufacturing cost is also low because of their simple design and fewer parts. This means these tractors are cheaper than tractors with turbochargers. Linear power delivery and instant response make the driving experience more engaging.
However, NA engines offer a lower power density. This means that a bigger CC engine is required to produce the same power output as a turbocharged engine. Also, their emission level is higher than that of their turbocharged counterparts, particularly under heavy loads.
Turbocharged Tractor Engine
A turbocharged engine comes equipped with a turbocharger for force induction of extra compressed air into the engine. This turbocharger has two main components: compressor and turbine wheel. The exhaust gases emitted by the engine enter the inlet port of the turbocharger at high pressure. The turbine wheel spins because of this high-pressure air. This also makes the compressor wheel spin, which causes a vast amount of air to be drawn in and expelled via the exhaust port.
This compressed air travels through an intercooler to be injected into the cylinders. The role of the intercooler is to cool the air, which is heated due to hot exhaust gases. The turbocharged engines are powerful enough to produce the same or even more power output with a smaller capacity than NA engines. Even at lower RPMs, they offer more torque. Thus, the initial acceleration or pickup is excellent. As they use cleaner air, turbocharged engines are more refined and produce less noise.
More components mean higher manufacturing costs. Also, these engines are more complex and thus, their maintenance or repair is tough and expensive. There is also an issue of turbo lag, which causes a slight delay in the power delivery when the operator accelerates.
Hope you now understand how a tractor engine works. It will help you maintain and service your tractor. Also, you can now see which engine type is most suitable if you are looking to buy a new tractor. Tractorkarvan has listed a wide range of tractors with all of their key specifications, including the engine and fuel pump type. You can check these details to choose an ideal tractor that fits your farming needs and budget. Remember that a smooth-running engine is crucial for your tractor as it has a huge impact on its performance and fuel efficiency.
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