Motor shaft coupling strength calculation

In order to reduce the effect of galvanic action between two unlike materials, line shaft section shall be connected by left-hand threaded couplings or keyway couplings, composed of a material similar or superior to those if line shafts. Coupling thread shall be nontapered and tend to tighten during pump operation.

The maximum combined shear stress in the coupling shall not exceed 20 percent of the tensile yield strength or more than 12 percent of the ultimate tensile strength of the coupling material. Following formula will help you calculate

S- combined shear stress, psi(Kpa)

f- total axial thrust, including the weight of the shaft and all rotating parts supported by it. pounds(newtons)

N- rated speed r/min

D- ourside diameter of the coupling, in(mm)

d- inside diameter of the coupling at the root of the threads, in(mm)

P- horsepower(watts)

Our motor shaft coupling is designed based on a lot of application analysis. It is incorrect to select the bigger size motor shaft coupling to ensure its safety factor.