MULTI-STAGE DRY PUMP

摘要

A multi-stage dry pump has pump chambers each including a cylinder and a rotor received in the cylinder, a first rotor shaft functioning as the rotating shaft of the rotors, a fixed bearing for rotatably supporting the first rotor shaft and restricting axial movement of the first rotor shaft, and a free bearing for rotatably supporting the first rotor shaft and permitting axial movement of the first rotor shaft. The pump chambers are arranged between the fixed bearing and the free bearing. Of the pump chambers, a first pump, the suction side of which has low pressure, is placed close to the fixed bearing.