Engineering/Design/Development >> Operating Principles, Cammed Vaned Pumps

Operating Principle of Weldon Cammed Vane Pumps (for slung vaned pumps, click here)
The Weldon cammed vane pump is a positive displacement design used for over six decades in aerospace and industrial applications. These versatile pumps have a proven long life, are self-priming, lightweight, and capable of handling varied non-corrosive liquids . Airborne applications are rated excellent for altitude performance. The displacement of these pumps can be varied over a considerable range by using different standard rotors. The direct drive pump motors are 12 or 28 Volt DC, explosion resistant, permanent magnet type rated for continuous duty. The pumps may also be driven mechanically.

The pumping cartridge essentially consists of a rotor, stator, a stator cover, two vanes or blades, and a blade retaining ring. The cartridge is housed and ported in various ways, depending on the specific application. The two vanes reciprocate in slots in the stator and are spring loaded against the rotor cam, where they act as fluid-sealing members. These vanes, along with the porting pattern in the cover, divide the stator into two separate pumping chambers.

As the rotor land (high point) moves past an inlet port, followed by the rotor drop (low point), the gradual increase in volume of the inlet cavity creates a low pressure area, causing fluid to flow into the chamber. Continued rotation transports the trapped fluid to the outlet port. The volume of the cavity, having been reduced at this point, positively displaces the fluid.

While this activity has been taking place, another rotor lobe has been going through the same procedure on the other side of the pump. During each revolution, fluid is transported in each of the three rotor “drops”, twice (once against each vane abutment). This gives the pump a pressure balanced, two sided action which is a decided design advantage as pressures increase in various applications.

Inlet filtration is strongly recommended to provide maximum performance and extend the life of any positive displacement pump.