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Engine is the heart of any vehicle and farm tractors are no different. A tractor engine determines the overall performance of a tractor on the field. So, the need to maintain the working of tractor engine efficiently. You need to know all about a tractor engine, including engine parts, types, and working, among others. This article will explore the different types of tractor engines and how they work.
A tractor engine works to deliver high torque at slow speed. Like other vehicles, tractor are also made of various parts like tyres, chassis and engines. The engine is the most crucial part of a tractor. The tractor engine is made of parts like cylinder, piston, crankshaft, camshaft, fuel injector, and flywheel. Let us go through the list of the tractor engine parts.
A cylinder is the key component of the internal combustion (IC) engine. All engine functions occur inside the cylinder, including suction, compression, combustion and exhaust. It guides the piston.
The cylinder handles all the pressure and heat produced after fuel combustion. This is why cast steel and cast iron are used to make cylinders. Their design allows them to have high compressive strength. The engine cylinder needs cooling as it works under extreme pressure and high temperature.
A piston moves within the cylinder in a repetitive up-and-down linear motion. It uses the connecting rod to transfer mechanical energy to the engine crankshaft. A piston also must withstand high temperatures and pressure. It is made strong using cast iron or aluminium alloy. The sealing effect between the piston and cylinder is provided by piston rings.
The primary purpose of the crankshaft is to convert linear motion into rotary motion. The connecting rod transfers the thrust or power to the crankshaft. This power is further transferred to the flywheel to move the tractor.
The casting and forging process is used to make a crankshaft. The material used in this process is cast iron or alloy steel.
The camshaft operates poppet valves and fuel injectors in an engine. It is a timing device to control the opening/closing of the intake/exhaust valves. These valves manage the flow of air and exhaust gases by closing and opening in line with the crankshaft. In addition, it sets the valve overlap occurring on the exhaust stroke at the top dead centre. A camshaft is made of materials like billet steel and chilled iron castings.
An injector injects fuel when the compression stroke ends while atomizing fuel into droplets properly. During the IC engine working, the air is forced into the cylinder in the suction stroke. This air is then compressed to extremely high pressure raising its temperature to a value suitable for fuel ignition.
The fuel is converted into small droplets during the injection process. As continuous heat is transferred to the fuel, it begins to ignite.
A flywheel operates in the form of a temporary reservoir of energy. Its primary purpose is to reduce speed fluctuations. It resists changes in its rotational speed that assists in steadying the shaft rotation. The flywheel stores energy which is supplied when needed. It makes use of the conserved rotational energy for smoothening the power delivery from the tractor engine.
The tractor engine is the most crucial component of a tractor as it provides the power needed to perform different farm tasks. Farmers are often confused about what type of engine to buy. Go through the upcoming sections if you are wondering how many types of engines are available and make the correct purchasing decision.
In a naturally aspirated (NA) engine, the air is drawn at atmospheric pressure from outside to be pushed into the combustion chamber. There is no external mechanism for forcing air into the cylinder. As the amount of fuel and air increases, bigger explosions are created to generate more amount of power.
With an increase in the tractor’s speed, the airflow rate into the engine also rises. This generates the necessary power required at higher speeds.
Naturally aspirated tractor engines are likely to have a larger displacement because they lack extra power. These tractor engines increase the number of cylinders or their bore to increase the volume of the combustion chamber and derive extra power.
Naturally aspirated tractor engines are considered old-fashioned as these tractor engines have been around for decades. In addition, there is no lag in these engines during starting, and the operator gets a steady growth in power. They offer high power at higher RPMs and high torque at lower RPMs without any delay.
The union of a turbocharger and a diesel engine is a match made in heaven. These tractor engines force air into the cylinders with the help of a turbocharger. This process is also known as forced induction. The turbocharger uses the exhaust gases moving out of the cylinder and thus needs no power from the tractor engine.
An air compressor is rotated by an exhaust-powered turbine that increases the flow of air to the cylinders, which in turn burns fuel more efficiently. Along with improving combustion efficiency, a turbocharger also offers additional horsepower. Using an optimized fuel-burning process, it extracts as high power as possible from the burnt fuel.
Air is considered a limiting factor as how much fuel is burnt relies on the amount of air forced into cylinders. A turbocharger not only fills more air in the cylinder bore but also leads to disturbance in the cylinder. Such turbulence improves combustion to a great extent. Therefore, a diesel tractor engine becomes more powerful, uses less fuel and runs cleaner.
An IC engine uses fuel and air to operate. The combustion chamber receives fuel directly via the fuel injectors. It also sucks air from outside using the air intake hose. This simple process becomes complex in forced induction engines. The turbocharger has to be connected to both the exhaust and intake systems.
In addition, it increases temperatures to extreme levels due to high speeds. A turbo also demands an effective cooling and lubrication system, adding to the engine’s complexity. Thus, the complexity and maintenance costs of turbo tractor engines are higher than NA tractor engines.
NA tractor engines are considered more reliable as they receive fresh and clean new air every time. As turbo tractor engines utilize used air, it is slightly stressful for the engine. In addition, maintenance costs increase because of additional components. It is seen that the general life expectancy of NA engines is better than turbo tractor engines.
The turbo tractor engine generates more power; however, they lag in initial acceleration. Exhaust gases are used by turbos for power, for which they need to create these gases. When starting the tractor, there are no exhaust gases. Thus, there is a slight lag in getting the turbo boost. There is no such lag in NA tractor engines.
Turbo tractor engines are more fuel-efficient than NA tractor engines. It is mainly because these engines are generally smaller in size and thus weigh less and burn less fuel. In addition, a turbocharger turns exhaust gases into useful air for the engine. Due to the optimal fuel-burning process, fuel is not wasted, and thus, the tractor becomes more efficient.
The kind of tractor engine manufactured by companies is known as an internal combustion engine. It helps to convert the fuel’s heat energy into mechanical work after burning it inside the tractor engine. The primary principle of all internal combustion engines is the same: air mixed with fuel in the right proportion will create an explosive mixture.
Most Indian tractors run on diesel, as this fuel type offers a high compression ratio ranging between 14:1 and 25:1. A diesel engine has a higher compression ratio than a petrol engine, leading to better efficiency. Due to this high ratio, diesel engines come with the highest thermal efficiency for modern tractors. After drawing air into the chamber, the engine compresses and heats it to high levels.
In the next step, the combustion chamber receives fuel with the help of a fuel injector. The fuel droplets come in contact with hot compressed air, resulting in the expansion of combustion gases. The piston is pushed downward by these gases to turn the crankshaft of the tractor ultimately. The rotating crankshaft makes torque available to do mechanical work.
If you want to know diesel engine works on which cycle, this section is for you. The operation cycle of the four-stroke tractor engine involves the following activities:
In this stroke, the inlet valve of the tractor engine opens while its piston moves down the engine cylinder. The cylinder receives air from outside. As the piston hits the bottom, the air gets filled in the cylinder. At last, the inlet valve is closed.
Both inlet and outlet valves remain closed in this stroke. As the piston rises, the mixture gets compressed in a tight space. When the compression stroke ends, fuel is injected into the cylinder, and ignition occurs as the fuel comes in contact with high-pressure and temperature air.
Both valves are still 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.
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.
Diesel engines are the most common type of engine used in Indian tractors. These tractor diesel engines are highly reliable and fuel-efficient. They compress air within the combustion chamber, igniting the fuel with pressurized and high-temperature air. The piston is forced downwards by the explosion, producing energy that is sent to the transmission system. Tractor diesel engines can operate for a longer period than petrol tractor engines as they are highly fuel efficient.
If you seek an answer to ‘how does a petrol engine work’, you have arrived at the correct place. A petrol engine works on small fields, common in small tractors and lawnmowers. These tractor engines are generally lightweight and compact. This makes them perfect for small-scale farm applications. Petrol engines ignite a mixture of fuel and air in the combustion chamber to produce power. This power is then transferred to the transmission and hydraulic systems of the tractor to perform various farm tasks.
Petrol engines are relatively simple to operate and maintain, making them popular for homeowners and small-scale farmers. However, petrol engines have lower fuel efficiency than diesel engines, which can result in higher operating costs in the long run.
Electric tractor engines are the newest in the market. They have an electric motor and a battery to provide energy to the tractor. These tractors offer high efficiency and produce less noise. But this engine system is not widely used in India as these tractors are highly priced.
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