Power Steering

Older systems use a belt-driven hydraulic pump and fluid; most modern cars use electric power steering. The assistance is usually stronger at low speeds for parking and lighter at high speeds. Hydraulic systems need a specific fluid; some use automatic transmission fluid, others a special power steering fluid. Mixing types can damage seals.

Sensors or a valve detect how hard the driver turns the wheel and add force to the steering rack in the same direction.

Heavy steering, whining noises or fluid leaks point to a problem. In hydraulic systems the fluid level should be checked. Holding the wheel on full lock for a long time strains a hydraulic pump and can make it whine.