What Is Power Steering?
Prior to the early 1950′s, you couldn’t buy a vehicle with power steering. Although the convenience of the option was very popular, some folks didn’t like the additional expense and chose to drive cheaper vehicles that didn’t have the luxury. In fact, it wasn’t until the early 1990′s that the feature became standard on all newly manufactured vehicles.
If you’ve ever had the misfortune of needing to maneuver quickly in a car or truck, then you probably don’t take the innovation of power steering for granted. Those who have never attempted to drive a vehicle that lacks the option would probably be surprised to see how big of a difference it makes. At high speeds, the momentum of your car makes it much easier to turn the wheel., But, at low speeds or when idling, turning the wheel requires strength. For example, when you’re trying to parallel park, there’s no momentum to leverage. Cranking the wheel can become a problem.
So, how exactly does it work? Well first of all, you should know that the feature is technically referred to as “power assisted steering.” True “power steering” is reserved for bigger, industrial type vehicles. The vast majority of cars on the road use a type of system called “rack and pinion”. Other, larger vehicles, like SUVS and full-sized pickup trucks, commonly feature “recirculating ball steering”.
Rack and Pinion
This type of setup uses a power unit that is built right into the rack assembly. When you turn the wheel, it causes the rotary valve to direct the flow of fluid towards the end of the appropriate power cylinder. The contrast of pressure created on either side of the cylinder aids in the movement of the rack, thereby drastically reducing the amount of force needed to turn the wheel. The excess fluid is then collected and returned to the tank by a control valve.
Recirculating Ball System
As with a rack and pinion system, this type of setup also features a control valve that regulates fluid pressure. However, in contrast to rack and pinion, recirculating ball steering uses steel balls that serve as rolling threads between the rack piston and the shaft. Using hydraulic pressure, the piston is moved up when you turn right, and down when you turn left.
Some newer cars have been implementing a system that uses electric components in the place of hydraulic systems. However, a rack and pinion system is usually in place to serve as a backup in case there is some sort of electric component failure.
The most common cause of failure is low fluid. Always make sure to maintain adequate fluid levels (along with every other fluids your vehicle needs, of course).