- Most cars operate on gasoline; gasoline is pumped into the gas tank at the gas station. When the car is started, there is an electric pump inside the gas tank that pumps the gas to the engine.
- The engine has four, five, six or eight cylinders. Some very expensive cars have 12-cylinder engines. The gas is distributed to each of the cylinders by the fuel injection system. The fuel injectors vaporize the gas, or turn it into a mist, and the spark plugs in the cylinder ignite the vaporized gas and cause it to explode. The car's ignition system tells the spark plugs when to explode at the correct time. The explosion pushes down a piston in the cylinder, causing the crankshaft to turn.
-
The engine crankshaft is connected to the transmission. The transmission has a series of gears. Most cars have four or five gears. If a car has an automatic transmission, the driver doesn't have to change the gears because the gears are changed automatically by a "brain" in the transmission.
With a manual transmission, the driver of the car changes the gears manually with a stick shift. Cars with manual transmission also have a clutch, which allows the driver to change gears smoothly without damaging the transmission. The transmission is connected to a differential or final drive. This is what makes the wheels turn. If the car is rear wheel drive, the transmission and differential are separate. The transmission is connected to the engine, which is then connected to the differential by a propeller shaft. If the car is front wheel drive the transmission and differential are combined together and called a transaxle, which is under the hood with the engine. - Brakes are used to slow and stop the car. The brake pedal inside the car is connected to a master cylinder in the engine compartment. When the brake pedal is pressed, the master cylinder sends brake fluid through the brake lines to brake calipers at each wheel. Each wheel has a brake rotor that turns around with the wheel. The calipers squeeze the brake lining onto brake rotors, which slows the car down.
- The electrical system performs many functions in a car. The battery and the alternator are the main parts of the electrical system. The alternator is connected to the engine with a belt, so when the engine is running the alternator is creating electricity, which is then stored in the battery. The battery is used to start the car. All of the car's electrical accessories run off of the battery, such as power windows and locks, radios and DVD players. The car's fuel pump, fuel injection system and ignition system also run off the car's electrical system.
