Spring Number of Active Coils

Written by Jerry Ratzlaff on . Posted in Fastener

spring compression 1Active coils are the open wound coils exerting energy while under a load of compression, extending, or deflection.  A coil is formed when it is wound one complete 360 degree helix starting with the second coil and count to the second coil on the other end.

Spring Number of Active coils formula

\(\large{ n_a = \frac {G \; d^4} {8 \; k_s \; D^3 } }\)


\(\large{ n_a }\) = number of active coils

\(\large{ D }\) = mean coil diameter

\(\large{ k_s }\) = spring constant

\(\large{ G }\) = shear modulus of material

\(\large{ d }\) = wire size


Tags: Equations for Spring