Automobile info

How a car works

This section describes the major interconnected systems that function together in the operation of a car. But first, it may be helpful to understand the basic way in which the typical car works.

Most cars made today have a front-mounted, petrol-burning engine; a manual or automatic transmission; and front-wheel drive. The typical engine is an internal-combustion engine, which works by burning a mixture of petrol and air inside closed cylinders. When you turn the car's ignition key, electricity from the battery causes the starting motor to crank the engine. Pistons move up and down inside the engine's cylinders. As the pistons move down, intake valves above the cylinders open, and fuel and air are sucked into the cylinders. The pistons then move back up the cylinders, compressing the fuel-air mixture. Electric sparks from the ignition system's spark plugs ignite the mixture, and the engine starts to run as the pistons move rapidly.

Expansion of the burning gases forces the pistons down, and these downstrokes provide the power that moves the car. The pistons' downstrokes turn the crankshaft. Power travels from the crankshaft to the transmission and, finally, to the front wheels. Burned gases escape as the exhaust valves above the cylinders open and the pistons move up, forcing the waste products out through the catalytic converter (if fitted), silencer, and exhaust pipe.