SKF alignment needle roller bearings have an outer ring with a convex sphered outside surface. Two polymer seating rings with a concave sphered inside surface that is encased in a drawn sheet steel sleeve are fitted over the outer ring, enabling the bearing to align itself. Alignment needle roller bearings are therefore insensitive to static misalignment of the shaft relative to the housing.
Nodes supplies alignment needle roller bearings without an inner ring RPNA and with an inner ring PNA. SKF bearings without an inner ring provide the optimum solution for compact arrangements if the shaft can be hardened and ground. In applications where it is not possible or uneconomical to harden and grind the shaft, bearings with an inner ring should be used.
The dimensions of SKF alignment needle roller bearings have not been standardized. However, with the exception of bearings with a 52 mm outside diameter, the inner ring bore and outside diameter are standardized, in accordance with ISO 15:1998, as follows:
- needle bearings with an outside diameter D ≤ 47 mm follow Diameter Series 0
- needle bearings with an outside diameter D ≥ 55 mm follow Diameter Series 9
SKF alignment needle roller bearings can compensate static misalignment up to 3° between the shaft and housing. These bearings are unable to accommodate any dynamic misalignment.