NKE 6211-NR-C3 Kugellager (55x106,5x21)

The mounting dimensions are 55x106.5x21 mm and the weight is 0.6 kg; technical details beyond these are shown in the specification table. The design is known, the three specification features are not: for these items neither the sealing nor the material nor the clearance is recorded in the product data, so all three are to be taken from the designation and the specification table.

These items are listed as deep groove ball bearings without the sealing version, the material and the clearance being recorded in the catalogue data. What applies regardless is the design principle: a single row of balls runs in one deep raceway groove in each of the inner and outer ring, the curvature radius of which is only slightly larger than the ball radius; from this follow a small contact area that widens into an ellipse under load, with low rolling friction, and the ability to transmit axial force in both directions through the groove shoulders alongside the radial force.

The bearing is non-separable, so the fitting force is to be introduced through the ring that receives the interference fit. The three unrecorded features take effect as follows, and each of them is to be clarified before selection. The sealing version decides the permissible speed and the load-independent frictional torque — a contact version shuts out moisture and fine dust and limits the speed in return, a non-contacting or shielded version behaves the other way round, and an open form requires sealing and lubrication from the surrounding design.

The material decides the load ratings and the environmental resistance, since a stainless material brings a lower hardness and therefore lower load ratings than a through-hardened standard bearing steel. The clearance decides how much allowance is available for the interference fit and the temperature gradient, and which residual clearance establishes itself in the warm running state.

For the specific item these three statements are to be taken from the designation and the specification table; they cannot be derived from membership of the series alone. Increased radial clearance C3 — Dimensional/form-fit equivalent — verify suffix-level details for critical applications. Matching suffixes are also listed by SKF (HC5C3, HC5C3WT, C3), FAG (C3), NSK (C3), NTN (C3) and NACHI (C3).