In cars, power steering helps drivers steer by increasing steering effort of the steering wheel. Hydraulic or electric actuators add controlled energy to the steering mechanism, so the driver can exert less effort to turn the steered wheels while driving at typical speeds, and minimize considerably the physical effort necessary to turn the wheels when a car is stopped or moving slowly.
There are hydraulic and electric power steering. At the hydraulic, the steering gear’s internal cavity is separated into two chambers by a sealed piston attached to the rack. Applying hydraulic fluid under pressure to one side of the piston while allowing fluid to return from the other side to a reservoir allows steering assistance.
At the electric power steering, an electric engine mounted to the side of the rack housing drives a ball-screw mechanism via a toothed rubber belt. The screw engages a spiral cut in the outside of the steering rack. A torque sensor connected to the pinion shaft signals a control computer when to provide assistance.
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