Rack and Pinion

Many vehicles use rack and pinion steering, where the steering wheel turns the pinion gear, the pinion moves the rack, which is a linear gear that meshes with the pinion, converting circular motion into linear motion along the transverse axis of the car. This motion applies steering torque to the ball joints that replaced previously used kingpins of the stub axle of the steered wheels via tie rods and a short lever arm called the steering arm.

Power steering helps drivers steer vehicles with little effort using the steering wheel. Hydraulic actuators add controlled energy to the steering mechanism, so the driver needs to provide only modest effort regardless of conditions. Power steering helps considerably when a vehicle is stopped or moving slowly. Also, power steering provides some feedback of forces acting on the front wheels to give an ongoing sense of how the wheels are interacting with the road.
Make
Model
Year