How Does a Car Work?
We can look at a car as a complete system whose parts must work separately but also work in various combinations. This view allows us see a car as a complete package with a purpose – moving us around so we don’t have to walk or ride a bicycle. The car we drive is held together as a complete unit that takes in fuel (air and gasoline) produces energy by burning this fuel combination, converts the energy into mechanical motion to turn the wheels and eliminates the unused part of the fuel as exhaust.
In some ways a car is like the human body, in that both use fuel, convert the fuel to energy and change the energy into mechanical motion. We also eliminate unneeded parts of the fuel as waste. Both the car and the human body have numerous individual parts that work together in sub-systems. We might get a better understanding of this idea by looking at the separate parts of a car.
The engine is sort of like the “brain” of the car but it is also a factory that produces the energy needed to move the car. With gasoline, diesel fuel or another type of fuel the engine creates energy as power and heat. When the fuel is combined with the correct amount of air the spark plugs cause the fuel/air combination to ignite.
The force of a minor “explosion” in a cylinder of the engine is converted to mechanical energy in the movement of the piston and rod. This turns the crank, a rotary motion that is passed through the transmission to the wheels. The wheels turn in a different direction than the rotating crank so gears must change this to a forward-rotating motion. The wheels then contact the ground through the tires and the friction pulls or pushes the car forward.
A transmission has the basic task of transferring the rotation motion of the engine to the wheels at the proper speed. This allows for smoother operation – slow speeds for getting started and higher speeds for traveling long distances. The “side to side” rotation of the engine and transmission must be changed to a forward rotation, as mentioned earlier. This occurs after the transmission does its work. Gears at the axle convert the rotation so that the energy generated by the engine can be used to move us forward or backward.
While this summary gives us a good idea of how a car works to provide transportation, we might want to take a bit closer look at the engine. When gasoline or other fuel is combined with air in the right amount the mixture can be burned. We only need to provide a spark to set this small explosion off. But the mixture must be compressed within the cylinder to provide the right pressure. When the fuel mixture is ignited the power of the explosion (combustion) pushes the piston down, causing it to rotate the crankshaft. This motion is transferred to the wheels and our car does its job.