The power steering system aids the driver, making almost any vehicle possible to steer with little physical effort. Most vehicles from 1950 to 2010 have hydraulic power steering systems.
Electric Power Steering
Electric power steering uses the torque from an electric motor to assist the movement of steering components. Electric power steering can be used to assist steering imput or take over the job if steering entirely.
Video: Electric Power Steering
Flushing a Power Steering System
In this Cars Simplified video, Steve shows an easy way to flush the power steering system.