Helical compression spring made of wire of circular cross section, especially for use in motor vehicles

A helical compression spring having a partially progressive characteristic, said spring comprising a first truncoconical spring portion whose coil of largest diameter is positioned at the extremity of the spring and a cylindrical spring portion, said first truncoconical spring portion having an inconstant wire diameter, the coils of said first truncoconical spring portion having the largest wire diameter disposed between regions of said first truncoconical spring portion of lesser wire diameter, one of said regions of lesser wire diameter working toward the extremity of said spring, the other of said regions joined integrally and coterminously with the cylindrical spring portion having a constant wire thickness, the coils of said first truncoconical spring portion being disposed in said spring such that at maximum load said coils lie inside one another in the form of a spiral and wherein there is integrally and coterminously disposed on said cylindrical spring portion at its end opposed to said first truncoconical spring portion, a second truncoconical spring portion, said second truncoconical spring portion having its end of largest diameter disposed at its extremity away from said cylindrical spring portion, said second truncoconical spring portion being a spring of inconstant wire diameter, the coils of said second truncoconical spring portion of largest wire diameter being disposed between regions of said second truncoconical spring portion of lesser diameter, one of said regions of lesser wire diameter reaching toward the extremity of said spring, the other of said regions joining integrally and coterminously said cylindrical spring portion of constant wire diameter.