Almost all mechanically propelled farm machines are fitted with a diesel engine. The reason why we use engines is simple. An engine converts chemical energy into a more usable mechanical energy/force.
However, it’s not the engine that turns the wheels – it is in fact a complex gear arrangement known as the transmission which is powered by the engine. While a tractor and a car are quite different, the purpose of the engine is the same – think of it as the equivalent of a heart in a human or an animal. It is an essential component needed for all the functions to work.
Our hearts pump oxygenated blood around our body and help fuel our muscles, which in turn are responsible for movement. A tractor’s engine not only powers the transmission but also multiple other functions such as the PTO (power take-off) shaft and the hydraulic pump etc. It also creates electrical power for the heater, radio and other devices.
All engines create heat when running, therefore a fan and cooling pack is essential to cool the engine.
For decades, an internal combustion engine was the most efficient way of generating mechanical energy and still is in some instances.
In recent years, we’ve seen more and more electric battery-powered vehicles, but mainly cars, not farm machinery. Similar to a mobile phone, these electric vehicles have a battery that stores chemical energy. This is then converted into electrical energy and, using a motor, is then converted into mechanical energy in the form of a rotational force.
How an engine works
The trusted diesel engine has been around since the 19th century when a man named Rudolf Diesel invented an engine to run on diesel fuel.
Inside a diesel engine, pistons compress air to increase the temperature inside the cylinders. A component called the injector then injects a small amount of diesel into each of the cylinders which ignites/combusts at the point of contact with the high temperature.
This creates a controlled explosion known as the combustion process. At this point, chemical energy has been converted into mechanical energy. This causes the piston to move downwards, in turn transferring energy to the crankshaft and from there, through the powertrain. When the piston is pushed downwards, it simultaneously draws air into the cylinder to begin the process again at which point the engine is running.
The four stages of the combustion cycle.
After the combustion process, there are leftover gases known as exhaust gases. These gases are forced out of the cylinder as the piston is pushed up. Valves within the cylinder head control the inflow of fresh air and outflow of leftover exhaust gases. Each piston moves in sync with one other piston to create balance in the engine. The more the engine is revved, the faster the combustion cycle takes place. For the process to work, the timing is critical as it all takes place in milliseconds.
Horsepower
Different types of diesel engines will have varying size cylinders, pistons, compression ratios etc, all of which impacts how much power the engine produces. The higher the ratio and larger the cylinder/piston, the more power is generated.
A cutaway view of a typical diesel engine.
In agricultural tractors and loaders, the common number of cylinders is either four or six. We determine engine power using the term horsepower (hp).
Torque
The reason why diesel fuel is used over petrol in almost all agricultural vehicles is simply down to its efficiency. Diesel engines make good use of the fuel they burn and provide good torque. Torque is a twisting force – the larger the force, the more power the engine has.
In order to get more power out of an engine, we fit turbochargers. A turbocharger is a type of turbine – something used to move a lot of air very quickly. Pressure from the exhaust gases spins the turbocharger at a very high speed. Fresh air is then forced back into the engine.
Turbocharger
Since air is critical in an engines combustion cycle, the more air you can put in, the more power can be got out. That is where the turbocharger helps. The whistling sound sometimes heard near one of these engines is caused by the turbocharger, or ‘turbo’ for short.
A 136hp four-cylinder diesel engine fitted within a Claas telehandler.
Modern diesel engines are fitted with complex equipment to reduce the harmful exhaust gas emissions, leaving them less harmful to the atmosphere.
So when you hear an engine running in a car or tractor, remember that this is the process happening over and over again thousands of times per minute.
Finally, remember that engines can be dangerous when running. Not only do they contain a high number of moving parts, but they are noisy and extremely hot. Always avoid coming into contact with a running engine.
Almost all mechanically propelled farm machines are fitted with a diesel engine. The reason why we use engines is simple. An engine converts chemical energy into a more usable mechanical energy/force.
However, it’s not the engine that turns the wheels – it is in fact a complex gear arrangement known as the transmission which is powered by the engine. While a tractor and a car are quite different, the purpose of the engine is the same – think of it as the equivalent of a heart in a human or an animal. It is an essential component needed for all the functions to work.
Our hearts pump oxygenated blood around our body and help fuel our muscles, which in turn are responsible for movement. A tractor’s engine not only powers the transmission but also multiple other functions such as the PTO (power take-off) shaft and the hydraulic pump etc. It also creates electrical power for the heater, radio and other devices.
All engines create heat when running, therefore a fan and cooling pack is essential to cool the engine.
For decades, an internal combustion engine was the most efficient way of generating mechanical energy and still is in some instances.
In recent years, we’ve seen more and more electric battery-powered vehicles, but mainly cars, not farm machinery. Similar to a mobile phone, these electric vehicles have a battery that stores chemical energy. This is then converted into electrical energy and, using a motor, is then converted into mechanical energy in the form of a rotational force.
How an engine works
The trusted diesel engine has been around since the 19th century when a man named Rudolf Diesel invented an engine to run on diesel fuel.
Inside a diesel engine, pistons compress air to increase the temperature inside the cylinders. A component called the injector then injects a small amount of diesel into each of the cylinders which ignites/combusts at the point of contact with the high temperature.
This creates a controlled explosion known as the combustion process. At this point, chemical energy has been converted into mechanical energy. This causes the piston to move downwards, in turn transferring energy to the crankshaft and from there, through the powertrain. When the piston is pushed downwards, it simultaneously draws air into the cylinder to begin the process again at which point the engine is running.
The four stages of the combustion cycle.
After the combustion process, there are leftover gases known as exhaust gases. These gases are forced out of the cylinder as the piston is pushed up. Valves within the cylinder head control the inflow of fresh air and outflow of leftover exhaust gases. Each piston moves in sync with one other piston to create balance in the engine. The more the engine is revved, the faster the combustion cycle takes place. For the process to work, the timing is critical as it all takes place in milliseconds.
Horsepower
Different types of diesel engines will have varying size cylinders, pistons, compression ratios etc, all of which impacts how much power the engine produces. The higher the ratio and larger the cylinder/piston, the more power is generated.
A cutaway view of a typical diesel engine.
In agricultural tractors and loaders, the common number of cylinders is either four or six. We determine engine power using the term horsepower (hp).
Torque
The reason why diesel fuel is used over petrol in almost all agricultural vehicles is simply down to its efficiency. Diesel engines make good use of the fuel they burn and provide good torque. Torque is a twisting force – the larger the force, the more power the engine has.
In order to get more power out of an engine, we fit turbochargers. A turbocharger is a type of turbine – something used to move a lot of air very quickly. Pressure from the exhaust gases spins the turbocharger at a very high speed. Fresh air is then forced back into the engine.
Turbocharger
Since air is critical in an engines combustion cycle, the more air you can put in, the more power can be got out. That is where the turbocharger helps. The whistling sound sometimes heard near one of these engines is caused by the turbocharger, or ‘turbo’ for short.
A 136hp four-cylinder diesel engine fitted within a Claas telehandler.
Modern diesel engines are fitted with complex equipment to reduce the harmful exhaust gas emissions, leaving them less harmful to the atmosphere.
So when you hear an engine running in a car or tractor, remember that this is the process happening over and over again thousands of times per minute.
Finally, remember that engines can be dangerous when running. Not only do they contain a high number of moving parts, but they are noisy and extremely hot. Always avoid coming into contact with a running engine.
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