Tractors are the workhorses of modern agriculture and for good reason — they’re powerful, versatile and durable. The heart and soul of these legendary machines is of course the engine, and over time designers have replaced the unpredictable and dangerous steam engines with internal combustion engines that are far more powerful, efficient and reliable. But how do they work? Read on to find out!
Brief History of Tractor Engines
When tractors were first developed, they used enormous steam engines that were notoriously unreliable and difficult to maintain. These were phased out around the turn of the 20th century and replaced with internal combustion engines that were more compact yet still powerful and ran on a variety of fuels including kerosene, ethanol and gasoline. By the 1960s many of these engines were phased out in favor of more efficient internal combustion engines that ran on diesel and today, biodiesel.
How Tractor Engines Work
Diesel engines have become the predominant power behind modern tractors because they have the highest thermal efficiency of any internal or external combustion engine, thanks to their extremely high compression ratio. Unlike gasoline engines, the diesel engines in tractors use highly compressed hot air to ignite the fuel rather than spark plugs.
Once air is pulled into the combustion chamber, it is compressed to 580 pounds per square inch (PSI), which heats the air to a temperature of 1022 ËF (550ËC). At this point, fuel is injected into the combustion chamber using an injector that disperses the tiny droplets of fuel evenly throughout the chamber. These tiny droplets of diesel fuel then vaporize when they come in contact with the hot, compressed air, which causes a rapid expansion of combustion gases that drive the engine’s pistons downward, creating power that turns the crankshaft of the tractor.
Where the Power Goes
Tractor engines generate an enormous amount of power – anywhere from 18 to 575 horsepower or more. But that power does a lot more than simply move the tractor’s wheels. One of the reasons why tractor sales continue to climb around the world is that these machines are so versatile, thanks to their ability to transfer the power from their massive engines. This power can be harnessed to operate stationary equipment using PTO or power take off systems and it can even be used to supply hydraulic fluid and electric power to tractor attachments that are pulled behind or alongside the tractor like mowers, swathers, balers and plows.