Principles of naval engineering - Historic Naval Ships Association

PRINCIPLES OF NAVAL ENGINEERINGDISCHARGESUCTION38.108Figure 15-15.— Simple gear pump.type are frequently used as lubricating pumpson pumps and other auxiliary machinery.The herringbone gear pump (fig. 15-16) is amodification of the simple gearpump. In the herringbonegear pump, one discharge phase beginsbefore the previous discharge phase is entirelycomplete; this overlapping tends to give a steadierdischarge than that obtained with a simplegear pump. Herringbone gear pumps are sometimesused for low pressure fuel oil service, lubricatingoil service, and diesel oil service.The helical gear pump (fig. 15-17) is still anothermodification of the simple gear pump.Because of the helical gear design, the overlappingof successive discharges from spaces betweenthe teeth is even greater than it is in theRELIEF VALVE SUCTIONHERRINGBONEDISCHARGEFigure 15-16.— Herringbone gear pump.147. 113404