When the line bearing and thrust bearing are on one end of the shaft and the impeller is on the other end of the shaft, you have what is called an overhung design. It is much like a fishing rod that you hold on one end while the other ends flexes. ANSI pumps are overhung design.
An ANSI pump slings your process fluid, it doesn’t scoop it. For this reason and for the overhung design, it is very important for your ANSI pumps to operating as near their Best Efficiency Point (B.E.P.) as possible. Going off the curve sets up large unbalanced hydraulic forces on the impeller. This leads to shaft deflection, bent shafts and premature failure of bearings and seals.