with Border
The purpose of lip seals in needle roller bearings helps to extend the life of the bearing by reducing the ingress of contaminants, thus minimizing any wear and damage to the rolling elements and raceways.
Needle roller bearings with an inner ring are employed when the shaft cannot serve as a raceway for the rolling bearing. In such cases, the inner ring acts as a separate raceway for the needle rollers. During the rotation, the shaft can be moved axial free in relation to the housing, since the needle rollers move between the flange edges of the inner ring and the raceway.
Needle roller bearings without an inner ring are especially suitable for compact bearing arrangements in which the raceway on the shaft can be hardened and ground. By dispensing with a separate inner ring, the shaft can be designed to be thicker and stiffer. This saves space and increases the radial compactness of the bearing arrangement.