The heading covers iron or steel springs of all types, irrespective of their use, other than clock or watch springs of heading 91.14.
Springs are made from sheet metal, wire or rod of an elastic quality, in such a way that they have the property of returning to their original form even after considerable displacement. The heading includes the following types of springs :(A) Leaf-springs (single or laminated) chiefly used in the suspension systems of vehicles (e.g., railway locomotives and rolling stock, automobiles and carts). (B) Helical springs of which the two major groups are : (1) Helical coil springs, comprising compression, tension and torsion springs, made from wire or rod of round or rectangular section. They are used for numerous purposes (e.g., in vehicles and general engineering). (2) Volute springs, usually conical and made from wire or rod of rectangular or oval section or from flat strip. They are mainly used in shock-absorbers, buffers on rolling stock couplings, secateurs, hair clippers, etc. (C) Flat springs and flat spiral springs as used in spring operated motors, in locks, etc. (D) Discs springs and ring springs (as used in railway buffers, etc.). Springs may be equipped with U-bolts (e.g., for leaf-springs) or other fittings for assembly or attachment. Leaves for springs are also classified in this heading. The heading excludes : (a) Springs for shafts or sticks of umbrellas or sunshades (heading 66.03). (b) Spring washers (heading 73.18). (c) Springs assembled with other articles to form, for example, automatic door closers (heading 83.02), identifiable parts of machinery (Section XVI) or of the apparatus and instruments of Chapters 90, 91, etc. (d) Shock absorbers, and torsion bars of Section XVII.
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