Cylindrical roller bearings, single row, NU design

[NU1026]

Product information

Cylindrical roller bearings

Cylindrical roller bearings are a key component.Their geometry,the so-called logarithmic profile,provides an optimum stress distribution in the contact zones in the bearing.Their surface finish maximizes lubricant film formation and optimizes rolling motion of the rollers.The benefits derived from this compared with traditional designs include enhanced operational reliability and a greater insensitivity to misalignment.

Cylindrical roller bearings comprises the basic types

– single row cylindrical roller bearings,caged,mainly of the NU,NJ,NUP and N designs.

– double row cylindrical roller bearings,caged,mainly of the NNU and NN designs.

– multi-row cylindrical roller bearings,caged.

– single row full complement cylindrical roller bearings,mainly of the NCF and NJG designs.

– double row full complement cylindrical roller bearings,mainly of the NNF design.

– multi-row full complement cylindrical roller bearings,with four or eight rows of rollers.

In addition to the standard assortment the comprehensive,cylindrical roller bearings consists of

– single row high-precision all-steel or hybrid cylindrical roller bearings.

– double row high-precision all-steel or hybrid cylindrical roller bearings.

– cylindrical roller bearings and bearing units for railway axleboxes.

– single row cylindrical roller bearings for traction motors for railway applications

– backing bearings for cold rolling mills of the cluster type.

– indexing roller units for continuous furnaces..

Single row cylindrical roller bearings.

The rollers in a single row cylindrical roller bearing.are always guided between the integral "open" flanges on one of the rings.These "open" flanges combined with the specially designed and surface treated roller ends,provide improved lubrication,reduced friction and consequently lower operating temperature.

The ring with the integral flanges together with the cylindrical roller and cage assembly can be separated from the other ring.This results in easy mounting and dismounting,particularly where the load conditions are such that interference fits are required for both rings.

Single row cylindrical roller bearings can accommodate heavy radial loads and high speeds.They are manufactured in several different designs,the main difference being in the configuration of the flanges.The most popular are the NU,N,NJ and NUP designs.

NU design

The outer ring of bearings of the NU design.has two integral flanges and the inner ring is without flanges.Axial displacement of the shaft with respect to the housing can be accommodated in both directions within the bearing itself.The bearings are therefore used as non-locating bearings.For manufacturing and maintenance reasons,the two outer ring flanges of large-size bearings of the NU design which are identified by a Drawing No.may not be integral but take the form of loose flange rings.

N design

The inner ring has two integral flanges and the outer ring is without flanges.Axial displacement of the shaft with respect to the housing can be accommodated in both directions within the bearing itself.The bearings are therefore used as non-locating bearings.

NJ design

The outer ring has two integral flanges and the inner ring one integral flange.The bearings are therefore suitable for the axial location of a shaft in one direction

NUP design

The outer ring has two integral flanges and the inner ring one integral flange and one non-integral flange in the form of a loose flange ring..The bearings can be used as locating bearings,i.e.they can provide axial location for a shaft in both directions

Double row cylindrical roller bearings have a low cross section,high load carrying capacity and high stiffness.Therefore they are mainly used in machine tools,rolling mill stands,plastic calenders,grinding mills and also large gearboxes.

Double row cylindrical roller bearings mainly in the NNU design.and the NN design..The bearings are separable,i.e.the ring with integral flanges together with the roller and cage assemblies can be mounted separately from the other bearing ring or all bearing components can be mounted separately.This facilitates the mounting,inspection and maintenance of these bearings.

Double row cylindrical roller bearings are produced with both cylindrical bore and tapered bore; bearings of the NN design are generally supplied with tapered bore.When mounting bearings with tapered bore it is possible to achieve a certain radial internal clearance or a given preload.

The bearings,except those of the NNUP design.allow axial displacements between shaft and housing to take place inside the bearing itself within certain limits.