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High precision cylindrical roller bearings are available in three different designs: two double row series NN 30 and NNU 49 and a high speed design, single row cylindrical roller bearing series N 10.
These bearings are normally according to the precision class SP, which corresponds approximately to tolerance class P5 and running accuracy P4. Better precision can be supplied on order.
The principal feature of the double row cylindrical roller bearings is to be able to withstand heavy radial loads in applications running at moderate speed.
When speed request is higher that the capability of the standard series, the single row series N 10 may be the solution.
The bearings series N 10 have the same section height as the series NN 30 and follow ISO Dimension Series 10.
These bearings are designed to fulfill different requirements from the double row cylindrical roller bearings. Instead of very high load carrying capacity, the N 10 series are used where increased speed capability and more compact design are needed.
The double row cylindrical roller bearings of the series NN follow ISO Dimension Series 30 and are available with either cylindrical bore or tapered bore (with taper 1:12).
These bearings are able to carry heavy loads and offer a good compromise between achievable speed and high rigidity.
In the machine tools industry, cylindrical roller bearings are generally supplied with a tapered bore, as this design allows a certain radial internal clearance or preload to be achieved by adjustment, when mounting the bearings on a tapered shaft.
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