
86 Practical Centrifugal Pumps
4.2.2 Calculating shaft deflection
Shaft deflection is calculated by treating the shaft as a cantilever beam using an expanded
version of the beam formula (Figure 4.13). The formula for the deflection of a shaft with
three major diameters in the overhung section is as given below.
333332
CB A L
3
PC B C A B A L
EI I I I
δ
−−×
=+ ++
Figure 4.13
Calculating shaft deflection
Where
ABCL
= Shaft Deflection
P = Radial Resultant force
E = Young's Modulus Modulus of Elasticity of the shaft material
A, B, C, L = Distances from impeller as shown in the figure above
I , I , I , I = Moments
δ
−
of Inertia at various diamet ...