ah Rotary Gear pumps An internal rotary
gear pumps is a positive displacement pump which employs a rotor and idler
gear assembly to generate its flow. The assembly is offset, using a crescent
adjacent to the inner gear, all within an outer gear. Rotary pumps are most
commonly used to circulate lubricating oil in mechanical equipment or to
provide pressure for hydraulic operating systems. The oil used in these systems
is usually cleaned by filtering. The pumped fluid lubricates the pump’s
internal gears and bearings. Rotary pumps are a type of positive displacement
pump where for each revolution, a fixed volume of fluid is moved. These pumps
are self-priming and provide near constant delivered capacity no matter the
pressure. 

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