Patent ID: 8348650

Claim:
A root pump comprising a rotary shaft, a housing supporting the rotary shaft through a bearing, and a rotor rotatable integrally with the rotary shaft, the root pump transporting fluid through rotation of the rotor together with the rotary shaft, wherein the housing is a two-piece structure comprising a lower housing member and an upper housing member, wherein the lower housing member includes a lower accommodating portion that has an upward opening so as to receive a lower portion of the bearing and the upper housing member includes an upper accommodating portion that has a downward opening so as to accommodate an upper portion of the bearing, wherein, with the upper and lower housing members joined together, the upper and lower accommodating portions form a bearing accommodating portion that accommodates the entire bearing, and wherein the root pump includes a positioning member that is attached to the bearing and fixed to the lower housing member in such a manner that the bearing is accommodated in the lower accommodating portion in a positioned state.