A truncated cone helical spring is a type of helical compression spring with a truncated cone shape. It belongs to the category of nonlinear characteristic line helical springs and is mainly used in load-bearing components in space-constrained environments. Based on the cross-sectional shape of the material, this spring is divided into two types: constant pitch and constant helix angle. The constant pitch spring's wire axis projection follows an Archimedean spiral, while the constant helix angle type follows a logarithmic spiral. Both types have circular cross-sections.
The load-deformation curve of a truncated cone helical spring is divided into a linear segment and a nonlinear gradually increasing segment. A larger cone angle θ results in a higher rate of change of natural frequency, which helps to mitigate resonance. Compared to a cylindrical helical spring of the same external dimensions, it can withstand greater loads and produce greater deformation, while having a smaller full compression height and better lateral stability. When applied to the SS8 electric locomotive, the improved spring reduced the weight of a single unit by (2-3) kg, and the deformation under working load was lower than the original cylindrical spring design. The tail design facilitates fixed installation in confined spaces such as electronic products or toys.
