Lubrication 14 - Gear Pump
The gear pump delivers hydraulic- or engine oil self-primingly at relatively small constructional expenditure in the pressure range of up to 8 bar (Engine lubrication about 3 bar). If the suction pipe vented to the reservoir volume, it also works self-priming.
A gear wheel propels a second gear wheel, which rotates loosely or on an additional short stub shaft. Both gear wheels are tightly fit into a housing with very small wall distance. The oil is transported upward between the tooth spaces and the wall by the rotating motion of the two gear wheels. The oil cannot flow back in the center, because the teeth interlock.