these springs are used in the high speed train,the diameter of the spring wire always between dia22--dia50. the material 51CrV4 these sprigns are always made of the material 51CrV4 and 52CrMoV4, they have the good performance, such as the fatigue, the salt-resistant. we supply these springs to the chinese railway ,and export to the Amercian and India raliways. locomotive spring