Inner rings with non-directionally ground raceway
Inner rings (fig 1) are a simple and quick possibility to provide a counterface for radial shaft seals without any hardening and fine machining of the shaft. The rings are simply pushed in position e.g. over a worn area. Inner rings together with SKF radial shaft seals are a perfect compatible sealing system (fig 2).
When using an inner ring with sufficient width, it can be used for both functions: as seal counterface and raceway for a needle roller bearing.
Inner rings are recommended for applications where operating conditions for the seals and the counterface are difficult, particularly where solid contaminants can reach the seals or where PTFE seal materials with abrasive fillers are used.
In applications where seal wear and shaft damage can be expected, SKF recommends installing the ring before the machine is operational. By installing the ring from the outset it will not be necessary to rework the shaft and the original seal size can be used as replacement.