Effects of an annular groove formed on contact surface on fretting wear between inner ring and backing ring of railway axle journal bearings

Abstract Fretting wear is surface damage caused by repeated slight relative slips between two contact surfaces. In railway applications, fretting wear can occur between the inner ring and the backing ring of an axle journal tapered roller bearing. The authors found that the fretting wear area of the backing ring is approximately coincident with the area where the amplitude of the contact pressure is larger. Thus the fretting wear may be reduced by designing so that the backing ring side face, where the contact pressure increases, does not contact the inboard inner ring side face. The aim of our study is to obtain knowledge to suppress the fretting wear of the axle bearings and to prevent the fretting wear particles from entering the inside of the bearing, without increasing the number of bearing components. Therefore, we have conducted a rotation test of a full-scale railway axle bearing with a backing ring formed an annular groove on its side face to investigate the fretting wear preventive effect. Results indicate that the annular groove on the backing ring side face was found to be effective in collecting fretting wear particles in the groove, but the fretting wear generated in the backing ring with the annular groove was more noticeable than that in the backing ring without the annular groove. We conclude that the formation of an annular groove on the contact surface between the inner ring and the backing ring is ineffective in preventing the fretting wear of axle journal bearings.