Abstract: Lobe pumps have rings which can be located at least partially in at least one of cover plates and rotors, if not both to provide at least thrust bearings to space the rotors from the cover plates. Some rotors may have voids in ears to make the rotor lighter in weight with the voids potentially capped, symmetrically disposed, arcuately shaped and/or have other desirable features. Some rotors may have ears extending beyond cutouts which may extend beyond hubs, if not beyond hub extensions as well which may receive cover spigots thereabout. Some rings may act as radial bearings as well when located in the cover spigots.

Abstract: Lobe pumps have rings which can be located at least partially in at least one of cover plates and rotors, if not both to provide at least thrust bearings to space the rotors from the cover plates. Some rotors may have voids in ears to make the rotor lighter in weight with the voids potentially capped, symmetrically disposed, arcuately shaped and/or have other desirable features. Some rotors may have ears extending beyond cutouts which may extend beyond hubs, if not beyond hub extensions as well which may receive cover spigots thereabout. Some rings may act as radial bearings as well when located in the cover spigots.