Technology is a fickle friend, nudging us forward with one hand while charging exorbitant tolls with the other. Modern engines that impress us with power and efficiency are being decoupled from the manual transmissions that help them sing. Stout body structures guard us from peril in a crash but are so heavy and hard to see out of that we’re more liable to bump into hazards easily avoided by truly wieldy cars. Electronic stability and traction aids are wonderful except when there’s no way to disable them.
Electrically assisted power steering (EPS) is the latest technological cross we bear. Replacing hydraulic assist with a computer-controlled electric motor seemed like a reasonable idea when it first surfaced. Someday every car control will be by-wire; today’s EPS looks like a step in that direction. But in the past decade of driving EPS-equipped cars, we’ve found them lacking in feel, poorly tuned, and sometimes simply weird in comparison with the hydraulic-assist setups that have benefited from more than half a century of development.
This matters because steering is the driver’s main line of communication with the car; distortion in the guidance channel makes every other perception more difficult to comprehend.
Hydraulic Power Steering
The steering gear's internal cavity is divided into two chambers by a sealed piston attached to the rack. Applying pressurized hydraulic fluid to one side of the piston while allowing fluid to return from the other side to a reservoir provides steering assistance. A valve attached to the pinion shaft controls the hydraulic-fluid flow.
Pinion Shaft Steering Torque Sensor Rack-and-Pinion Housing 
Electric Motor
Ball-screw Mechanism 
Steering Rack 
Drive Belt
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