Types of Oil Pumps

 Gear-type oil pump

Gear-type oil pumps have
a primary gear that is driven by an external member, and which drives a companion
gear.  Oil is forced into the pump cavity, around each gear, and out the other side
into the oil passages.  The pressure is derived from the action of the meshed gear
teeth, which prevents oil from passing between the gears, forcing it around the
outside of each gear instead.  The oil pump incorporates a pressure relief valve, a
spring-loaded ball that rises when the desired pressure is reached, allowing the
excess oil to be delivered to the inlet side of the pum

 
Rotor-type oil pump

A rotor-type oil pump for sucking and discharging oil to be supplied to a variety of oil-requiring parts of an automotive engine. The oil pump comprises a generally annular outer rotor which is rotatably disposed in a pump casing. A generally annular inner rotor is disposed eccentrically inside the outer rotor and has an external gear which is partly in mesh with the internal gear of the outer rotor. The outer rotor is designed such that stress at the tooth base section of the internal gear is generally equal to stress at the tooth base section of the external gear of the inner rotor in their dynamic condition, thereby reducing the thickness of the tooth base section of the outer rotor.

Crescent type oil pump 

 

Vane Type oil pump