A type of rotary positive displacement pump consisting of a pair of externally timed rotors such that each is driven independently and the rotors are non-contacting. Rotor designs vary but some of the more common types include bi-wing (or scimitar), tri-lobe, and various multilobe designs. Similar in operation to a circumferential piston pump. Click here to view our How it Works video on this topic.

A type of internal gear pump that is driven by the idler gear and does not include a crescent. Click here to view our How it Works video on this topic. 

Any type of rotary positive displacement pump consisting of gears where the pumping results from the unmeshing and remeshing of gears. The liquid is carried between the gear teeth by the rotation of the pump. Common types of gear pumps include internal gear, external gear, and gerotor.

A type of gear pump featuring two identical external gears where one gear is the drive gear and one is the driven. The liquid is transferred from between the gear teeth by the rotation of the pump. Click here to view the Pump Report on this subject. 

A type of gear pump a drive gear featuring inward facing teeth called a rotor. This rotor turns an offset gear with fewer outward facing teeth called an idler. A crescent shape protruding from the head of the pump creates this offset and seals the pumping cavities formed between the gear teeth. Click here to view our How it Works video on this subject.