Four Point Contact B. SKF QJ317 N2MA

The SKF QJ317 N2MA four-point bearing, measuring 85 × 180 × 41 mm, accommodates high axial forces in both directions whilst requiring minimal axial installation space.

The QJ317 N2MA four-point bearing belongs to the group of radial angular contact ball bearings and is characterised by its split inner ring. This design primarily accommodates axial forces in both directions, yet requires less axial installation space than two separate angular contact ball bearings. Designed as an open bearing in SKF Explorer quality with standard radial clearance and a brass cage, the design operates within a temperature range of -30 to +150 degrees.

What is the QJ317 N2MA four-point bearing suitable for?

Design engineers primarily use this bearing where high axial loads occur in alternating directions and installation space is limited. It is often used as a pure axial bearing for high axial loads, combined with a separate radial bearing. If the outer ring is radially unsupported in the housing, the bearing transmits only axial forces. As a result, the four-point contact is limited to two contact points at a time under purely axial loads, which reduces friction and heat generation during continuous operation.

What is the function of the retaining grooves and the split inner ring in the QJ317 N2MA?

The split inner ring allows for the accommodation of a large number of rolling elements and simplifies assembly, as the outer ring and the two halves of the inner ring can be fitted separately. The suffix N2MA denotes two retaining grooves in the outer ring, offset by 180 degrees, as well as a solid brass cage. The retaining grooves serve to secure the outer ring against rotation within the housing by means of dowel pins. With a tolerance class of P6 for dimensional accuracy and P5 for running accuracy, the bearing meets high standards for concentricity and fit accuracy.