a deaerator shaft may have a tubular intake segment that forms an intake end of the deaerator shaft , a tubular sleeve attachment segment that is adjacent to the intake segment , a tubular central segment that is adjacent to the sleeve attachment segment , the central segment having a third diameter that is greater than the second diameter , the central segment comprising a protruding ring that radially extends from the central segment and divides the central segment , the protruding ring having opposing flat surfaces , and a tubular discharge segment that forms a discharge end of the deaerator shaft . a gear may have a central ring positioned along an axis , opposing tabs that extend from a first axial side of the central ring , and a shouldered ring that extends from a second axial side of the central ring , the shouldered ring having a lip that extends radially inward toward the axis .