Also known as power assisted steering, power steering is a mechanism that helps the driver of an automobile to steer the vehicle. In most automobiles, it relies on a hydraulic system to aid in turning the vehicle’s wheels. It is a standard feature in nearly every modern car and truck.
There are primarily two types of power steering systems, rack-and-pinion and the recirculating ball. Rack-and-pinion is the system found in most vehicles. The recirculating ball is largely known as one of the first systems to be implemented in automobiles. Although not as widespread, the recirculating ball is still used in some modern trucks.
A rack-and-pinion system is comprised of two main components: the rack-and-pinion itself and a power steering pump. Situated perpendicular behind the wheels of the vehicle, the rack-and-pinion is generally a piece of metal tubing that is roughly three inches in diameter and three feet in length. Inside the tube, there is a flat piece of metal that has been cut to include teeth on its top. In the center of the rack-and-pinion is a round seal that seals either side of the rack, one at a time.
In these systems, two high-pressure hoses from the steering mechanism are connected to both sides of the center seal. One directs high-pressure hydraulic fluid from the power steering pump to the steering mechanism, while the other allows fluid to flow back to the pump. When the steering wheel is turned left or right, the steering mechanism allows the hydraulic fluid to pass to that side of the rack. It is the pressure that gives the vehicle power an assist by pushing the seal and rack in one direction or the other.
The recirculating ball is a smaller power steering system attached to the vehicle frame on the driver’s side. This system is comprised of a threaded shaft about 12 inches long, in addition to an input shaft that connects to it and the steering column. Aside from the construction, the system works in nearly identical fashion to rack-and-pinion. Power steering fluid passes through the steering mechanism, which aids the driver in turning either left or right.
While new types of power steering have emerged, the core of most systems is the pump, complimented by a belt that is powered by the vehicle’s engine. Even the older recirculating ball system borrows the pump’s concept of moving high-pressure fluid back and forth. Due to the fact that the hoses moving the fluid are susceptible to developing leaks, drivers are encouraged to have them inspected by an auto mechanic during every oil change.