FAG NNU4921-S-K-M-SP Zylinderrollenlager (105x145x40)

As a cylindrical roller bearing, this bearing carries high radial loads with limited axial capacity. At 105x145x40 mm and a unit weight of 1.87 kg, the installation envelope is fixed; further technical details are held in the specification table. This variant features reduced radial clearance (C2). This configuration presupposes a controlled bearing position — reduced clearance (C2) leaves the fit and the temperature gradient less latitude than a standard clearance does.

Reduced clearance (C2) makes the initial radial play smaller than in the standard class. Once mounted and at operating temperature, less residual play therefore remains, the load zone reaches over a larger part of the circumference, and the radial force is distributed over more rollers at the same time; at the same time the radial deflection of the shaft under load comes out smaller and the running accuracy of the bearing position becomes closer.

That is the property sought wherever shaft position governs function — in guides with geometric requirements as much as at bearing positions whose smooth running depends on a close radial play. The price for it is a smaller reserve: the interference fit of the inner ring, expansion by centrifugal force and a temperature difference between inner and outer ring consume the same play as in any other clearance class, there is simply less of it available here.

If the clearance is fully used up in service the roller set goes into preload; frictional torque and heat generation rise, and because the additional heat reduces the play further, the effect reinforces itself. This version therefore belongs at bearing positions with matched fits, a manageable temperature gradient and assured lubrication; here the choice of fits is not routine but part of the design.

The open form leaves sealing and relubrication to the surrounding construction, and the axial function of the bearing position is still determined by the rib arrangement, not by the clearance class. Solid brass cage — Dimensional/form-fit equivalent — verify suffix-level details for critical applications. Matching suffixes are also listed by SKF (M, MA, MB), NSK (M) and NTN (L1, G1, M).