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LET'S EXPLORE How things work

How does a car engine work?

An internal combustion engineAn internal combustion engineMost cars are driven by engines fuelled by petrol or diesel. These engines are called internal combustion engines. The engine supplies power to turn the wheels. The driver can go faster by pressing the accelerator (or gas) pedal. This increases the flow of fuel to the engine. Gears allow the car to be driven at different speeds without the engine running too slowly or too quickly.

Petrol engine

An illustration of an internal combustion engineAn illustration of an internal combustion engineMovement of a piston inside a cylinderMovement of a piston inside a cylinderPetrol is drawn from the fuel tank into the engine and sprayed into its cylinders, mixing with air. The petrol-air mixture is ignited by spark plugs, setting off mini-explosions. The hot gases produced force pistons inside the cylinders down.

Four (or more) cylinders spark, one after the other, very quickly. The crankshaft, to which the pistons are attached, turns the up-and-down motion of the pistons into a turning motion. The crankshaft is connected to the wheels, and so the car is driven along.

A hybrid electric vehicle (HEV) combines an internal combustion engine with batteries that power an electric motor. When the batteries run down, the petrol or diesel engine switches on and recharges them.

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