PRINCIPLES OF NAVAL ENGINEERING 



DISCHARGE 



SUCTION 



38.108 



Figure 15-15.— Simple gear pump. 



type are frequently used as lubricating pumps 

 on pumps and other auxiliary machinery. 



The herringbone gear pump (fig. 15-16) is a 

 modification of the simple gearpump. In the her- 

 ringbone gear pump, one discharge phase begins 

 before the previous discharge phase is entirely 

 complete; this overlapping tends to give a stead- 

 ier discharge than that obtained with a simple 

 gear pump. Herringbone gear pumps are some- 

 times used for low pressure fuel oil service, lu- 

 bricating oil service, and diesel oil service. 



The helical gear pump (fig. 15-17) is still an- 

 other modification of the simple gear pump. 

 Because of the helical gear design, the overlap- 

 ping of successive discharges from spaces be- 

 tween the teeth is even greater than it is in the 



RELIEF VALVE 



SUCTION 



HERRINGBONE 



DISCHARGE 



147. 113 



Figure 15-16.— Herringbone gear pump. 

 404 



