You can feel your car's power steering in action any time you turn your steering wheel or make sharp turns. But how does it work? The secret is hydraulic power, which is distributed from the engine two ways:
The Pump: Your car's engine uses an old-fashioned belt and pulley system to move what's called the rotary-vane pump. This pump has retractable vanes, or fan-like rods, that spin inside a chamber. The vanes pull in hydraulic fluid (how much is determined by how fast you're going) at low pressure and force it back out at high pressure.
The Rotary Valve: This valve, which sits inside the cylinder head, has the very important job of moving fluid in and out of the combustion chamber of your car's engine. Inside the valve is a thin rod of metal, called a torsion bar, that connects at one end to the steering wheel and twists whenever you make sharp turns or make any other steering wheel movements.
In a nutshell: The pump and the rotary valve partner up to distribute hydraulic power to your steering based on how sharp you're turning and how fast you're going.