Compound Springs:

Sometimes, more than one spring might be used. The springs might be utilized in parallel or in series. This combination is called the compound springs.

Springs in Parallel

Figure illustrated two springs connected in parallel. The springs are provided side by side.

Figure: Springs in Parallel

(a) Sum of the individual loads carried through each of spring is equal to the load carried by compound spring

                                             W₁ + W₂ = W

(b) The deflections of both of the springs as well as the combination are same

i.e.

                                                         Δ₁ = Δ₂  =Δ

         ∴                                        K₁  + K₂  = K

where K = Spring constant or stiffness of spring.