Classification of Rotary Pumps:

1. Gear Pumps: A Gear pump uses the meshing of gears to pump fluid by displacement. They are one of the most common types of pumps for hydraulic fluid power applications.

2. Vane Pumps: A rotary vane pump is a positive-displacement pump that consists of vanes mounted to a rotor that rotates inside of a cavity. In some cases these vanes can be variable length and/or tensioned to maintain contact with the walls as the pump rotates.

3. Lobe Pumps: Lobe pumps are similar to external gear pumps in operation in that fluid flows around the interior of the casing. Unlike external gear pumps, however, the lobes do not make contact. Lobe contact is prevented by external timing gears located in the gearbox.

4. Cam Pumps: In this model the intake is the lower tube on the right and the outlet

is at the top. The piston slide arm moves around inside a slot in the casing. As an eccentric cam rotates the circular plunger around the edge of the casing, fluid is swirled around the edge to the outlet port.

5. Screw Pumps: Screw pumps for power transmission systems are generally used only on submarines. Although low in efficiency and expensive, the screw pump is  suitable for  high  pressures  (3000  psi),  and delivers   fluid   with   little   noise   or   pressure pulsation.