Power steering is a system that eases the amount of effort required to steer. With assistance from external power sources steering is much smoother with a significant drop in resistance. Power steering was designed in the 1920s but only started to see widespread use around the 1980s.
The following article explains how some of the components found in power steering systems work.
• The pump is powered by the car's engine using a belt and pulley system. The pump houses a set of retractable vanes that are contained and spin inside an oval chamber. When the vanes spin they draw in hydraulic fluid from the return line at a low pressure and force it towards the outlet section at higher pressure. The flow provided by the pump increases as the car’s engine working faster. The pump is designed to provide suitable flow when the engine is in neutral. As a result, the pump shifts more fluid than is needed when the engine is working at higher speeds. The pump has a built in pressure relief valve to control the pressure making sure it doesn’t build up too high, especially at high engine speeds when large amounts of fluid are being pumped through the system.
• The rotary valve is another important component. When the driver is driving in a straight line, the system shouldn't adjust and provide any assist. The rotary valve detects the force on the steering and works in unison with the torsion bar. The torsion bar is a narrow bar of metal that twists accordingly when torque is applied to it. The top of the bar is attached to the steering column and the bottom of the bar is attached to the pinion. This turns the wheels so the amount of torque in the torsion bar is equal to the amount of torque the driver is exerting to turn the wheels. As the driver uses more torque to turn the wheels, the torsion bar works harder. The input from the steering column forms the interior part of a spool valve assembly. It is also attached to the top end of the torsion bar. The bottom end of the torsion bar is connected to the outside part of the spool valve. The torsion bar also controls the output of the steering gear, connected to either the pinion gear or the worm gear dependent on what kind of steering the car has fitted.