first thread component 82 and a second thread component 83 first thread component 82 extends from a first end 85 to a second end not shown and includes a plurality of thread sections one of which is indicated at 87 second thread component 83 extends from a first end not shown to a second end 90 and includes a plurality of thread portions one of which is indicated at 91 thread portions 91 are arranged between adjacent ones of thread sections 87 in a manner similar to that described above first thread component 82 and second thread component 83 each includes a pitch not separately labeled that pumps fluid from a low pressure portion of rotor 8 to a high pressure portion of rotor 8 to reduce ambient air ingestion along outer diametric surface 12 the particular angle of the pitch may vary depending upon the position of helical seal 80 in accordance with another aspect of the exemplary embodiment first and second thread components 82 and 83 are materially integrally formed with outer diametric surface 12 more specifically first thread component 82 and second thread component 53 are machined into rotor 8 however it should be understood that first thread component 83 and second thread component 83 may be formed on a separate sleeve like component that is secured to outer diametric surface 12 reference will now follow to fig4 and 5 wherein like reference numbers represent corresponding parts in the respective.