A vacuum pump having a rotary shaft that is rotated by a drive source has a main pump and a sub pump. The main pump includes a pump chamber and a gas transferring body that is located in the pump chamber. The main pump is driven by the drive source through the rotary shaft for transferring gas to an...http://www.google.de/patents/US7140846?utm_source=gb-gplus-sharePatent US7140846 - Vacuum pump having main and sub pumps
