Mechanical forces in transformers

In this paper a method of calculating the mechanical forces in transformers, based on mutual reactance between coils, is presented. A formula for the mutual inductance between coaxial solenoids is developed and from this expression the formula for the mechanical force between concentric cylindrical transformer coils is derived. The same method is followed to obtain the formula giving the mechanical force between individual coaxial coils. The method is checked by calculations of reactance of complicated arrangements of coils. Tables are given to facilitate calculations.