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Sep 21, 2017

power steering Houston, TXPower steering is standard on all new cars these days. It makes the steering less stiff and turning effortless. While most of us enjoy the benefit of power steering, few understand how it works. Find out all about how this process functions.

How Steering Worked in the Past

In a world before power steering, turning the steering wheel felt like driving an 18-wheeler truck and required arms of steel. Back then, cars used a simple rack and pinion system. The pinion is connected to a steering column that runs from the steering wheel down to the steering rack. When turning the steering wheel, the pinion rotates. This action causes the rack to move from side to side and turn the wheels. The only downside to the system was that it made steering heavy. This all changed when Chrysler pioneered hydraulically assisted steering in 1951, which revolutionized the automotive world.

Hydraulic Power Steering

In hydraulic-assisted steering, a rack and pinion or a steering box is still used but a power steering pump, torsion bar, and rotary valve are added.

Power Steering Pump

The power steering pump is the heart of the hydraulic system. It’s driven by a belt attached to the engine. Inside the pump are rotary vanes that spin. As the vanes spin, they draw hydraulic fluid from the fluid reservoir, pressurize it and send it down into the steering rack. The steering rack then pushes this pressurized fluid against a hydraulic piston. This action moves the steering rack right or left in a way that requires a lot less muscle from the driver.

Torsion Bar and Rotary Valve

Power steering only kicks in when the system senses the wheel turning. A torsion bar and rotary valve control the amount of fluid that enters the system from the fluid reservoir. The top of the torsion bar connects to the steering wheel and the bottom connects to the pinion or worm gear. When the car isn’t turning the valve remains closed, preventing fluid flowing into the steering gear. When you start to turn the wheel, the torsion bar senses this force. It starts to twist and rotates the rotary valve. As the valve turns, fluid flows into steering gear on the side that you want to turn. The pistons respond and the wheels start to turn.

Electric Power Steering

While hydraulic steering is still the most common type of power steering, electric steering is gaining ground. In Electric Power Assisted Steering (EPAS), electric motors are placed either on the steering column or on the steering rack. Electronic sensors pick up the force and rotation speed being applied when turning the wheel. It responds by adding in a proportional amount of force to help turn the wheels. Many believe electric power steering is better than hydraulic. It doesn’t run off the engine, making it a more efficient system that uses less gas.

The desire for better power steering isn’t over. Steer-by-wire is being touted as the way of the future. Its concept is based on video game steering wheels. It will eliminate mechanical steering linkage entirely and be controlled by sensors in the steering wheel. That, however, is a little further down the road.

This photo, “Hands on the wheel by Jimmy Liew used under CC BY-NC-ND 2.o. “Hands on the wheel” is licensed under CC BY 2.0 by Gay Family Kia.

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