Patent ID: 7563087

Claim:
A pump, comprising: a body forming a chamber; at least one rotor rotating in the chamber, the rotor having a shaft with a cylindrical outward face that has a first outer diameter portion and a second outer diameter portion, with a shoulder between the first outer diameter portion and the second outer diameter portion; and a body hub portion extending from the body and oriented axially and having a cylindrical inner diameter face in rotational sliding contact with one of the first or second outer diameter portions of the shaft, wherein a bushing clearance gap is defined at the contact between the inner diameter face of the body hub and the second outer diameter portion of the rotor shaft, and wherein the rotor has a circular axial facing surface and the body hub has an end facing axially that slidingly contacts the axial facing surface of the rotor to define a body hub clearance gap, further wherein the rotor and the body hub portion define between them a seal chamber, and wherein the body hub has a suction vent port penetrating the hub from the seal chamber.