In a centrifugal pump thrust refers to the axial movement of the shaft. The resultant thrust in most centrifugal pumps is towards the wet end or volute of the pump.
Up to about 65% of the pump’s efficiency the thrust is towards the bearings or power end of the pump, but above 65% of the pump’s efficiency the thrust shifts towards the wet end or volute.
Consider the following
- At start up the thrust occurs in both directions and accounts for some of the premature seal failures we experience when we start a centrifugal pump.
- It also means that in operation we could have excessive thrusting problems because a simple snap ring is often used to hold the shaft and bearing assembly in many standard pump designs.