A pump includes a front plate, a gear plate and a rear plate. A drive shaft has a drive gear, an arbor has a driven gear engaged with the drive gear, and first and second bearings are disposed in the gear plate. The first and second bearings receive the drive shaft and the arbor. The rear plate has drain ports adjacent ends of the drive shaft and the arbor. The arbor has an opening such that media that passes between the first bearing and an outer surface of the arbor is directed to the second drain port via the opening. A drain bushing is positioned against the front plate, and includes an opening for the drive shaft. The drain bushing has a chamber and a radial port. When pumped media passes between the first bearing and the drive shaft it is directed to the chamber and out the radial port.

An electric oil pump includes an electric motor and an oil pump that is driven by the motive power from an electric motor, wherein; the oil pump has an introducing channel that guides a drain oil that has leaked from an interior of the oil pump to an interior of the electric motor; and the electric motor has a discharging channel that discharges the drain oil that has been guided to the interior of the electric motor to a tank.

A uniaxial eccentric screw pump includes: a stator having a through hole 8a whose inner surface is formed in a female screw shape; a rotor that is a male screw shaft body inserted into the through hole of the stator; a plurality of shims that are arranged on a radially outside of the stator in a range from one end to the other end of the stator, are in surface contact with an outer surface of the stator, are capable of compressing the stator by moving radially inward with respect to the stator, and have, on an outer surface, an inclined surface gradually inclined radially inward or outward toward one end; and an adjustment member that is movable in an axial direction with respect to the stator and has a pressing part that can press the inclined surface of each of the shims.