It consists of one external and one internal meshing gear pair.
External gear is connected to
electric motor and hence is driving gear. Internal gear or ring gear is driven gear which rotates in same
direction as that of external gear. Between two gear a spacer called ‘crescent’ is located which is a
stationary pieces connected to housing. Inlet and
outlet ports are located in end plates.
External gear (driving gear) drives the
internal gear (Ring Gear). Portion where teeth start
meshing, a tight seal is created near port the
vacuum is created due to quick un meshing and oil
enters from oil tank through inlet port.
Oil is trapped between the internal and external gear teeth
on both sides of crescent (spacer) and is then
carried from inlet to outlet port. Meshing of gear
near outlet port reduces the volume or gap and oil
gets pressurized. These pumps make very less
noise.