Types of Power Steering Pumpsby Andrea Julian
Power steering systems date back to 1925 when they were first introduced by the Detroit pump manufacturer Vickers. Today, they are standard on most vehicles. Different types of power steering pumps are used to power the system. The main difference between the different types of pumps is the design of the fins that move the steering fluid that is inside the pump and expelled through built-up pressure. They are all similar in that they contain a rotor inside the pump housing that spins. There are three different types of pumps used in power steering systems.
Vane Power Steering Pump
Vane pumps are the most common type of power steering pump used. In this type of pump the rotor is housed in an oval- or elliptical-shaped housing where it turns. Vanes fitted to the outside diameter of the rotor sit against the housing walls as the rotor turns. When power steering fluid enters into the vane pump housing it is trapped between the vanes, the housing wall and the rotor. A subsequent pressure increase causes the fluid to be pumped out of the housing and then through the outlet chambers.
Roller Power Steering Pump
In a roller power steering pump, wide V-shaped grooves cut into the side of the rotor allow steel rollers to ride along the inside contour of the pump. The pump is contained in an oval-shaped housing within the pump body. Centrifugal force pushes the rollers to the oval's outer edge where they trap fluid, similar to the way the vanes catch the fluid in a vane pump. The pressurized fluid is forced out through two outlets in the pump, driving the power steering system.
Slipper Power Steering Pump
Like the vane and roller pump, the slipper power steering pump has a rotor housed in an elliptical-shaped chamber that rotates within the body of the pump. Fitted into wide slots on the rotor are springs that are topped with scrubber-type "slippers." The springs keep the slippers in constant contact with the wall of the pump. As fluid enters into the pump, pressure is built up and released to drive the power steering system.
- hand on steering whell image by Andrzej Borowicz from Fotolia.com