URB

Cylindrical rollerbearings

Cylindricalroller bearingsaremanufacturedin avarious range of constructive types and sizes, particularlysinglerowcylindrical rollerbearingsbut also two ormore row cylindrical roller bearings,with cages or rollerbyroller，as shown in the designs below.

Incase ofcylindrical rollerbearings,the rollersare laterally guided by the fixed ribs of one ring.

In case of bearings with cages,the ring with ribs and the rollers retained in the cage can be drawn out from the other ring,which means that these bearings are dismountable.

Therefore，bearings from joints canbe much easiermounted and dismounted，especiallywere interference fitsare needed for both rings due to the loading conditions.

Bearings areprovidedwithunloaded rollersat both generatrix ends.Therefore，the linear contact betweenrollersand ringsaltersadvantageously,i.e. peripheralstressesareavoided.

- single row
- double row
- without cage (full complement)

- single row - double row

- without cage (ful complement)

Suffixes

AR-Grinding addition on the inner ring raceway
B - Cylindrical roller bearings with extended inner ring
C2 - Radial clearance smaller than normal, bearings with interchangeable elements
C2NA- Radial clearance smaller than normal, bearings with non-interchangeable elements
C3- Radial clearance larger than normal,bearings with interchangeable elements
C3NA-Radial clearance larger than normal,bearings with non-interchangeable elements
D - Two-pieces inner ring
E - Cylindrical roller bearings,E-design (increased basic static and dynamic loads)
F - Machined steel or special cast iron cage
F2 - Constructive modification
K -Taperedbore bearing
M - Machined brass cage guided on the roling elements
M6 - Machined brass cage with integral rivets
MA-Machined brass cage guided in the outer ring
MA6- Machined brass cage with internal rivets guided on the outer ring
MB- Machined brass cage guided in the inner ring
MPA- viacileu Drass caye (Uie-plece)
N - Circular groove in the outer ring for snap ring
NA- Radial clearance,non-interchangeable elements
NR - Circular groove in the outer ring and snap ring
P - Two-pieces outer ring
P5 - Tolerance class more accurate than normal (P6)
P51 -Tolerance class P5 and radial clearance C1
P53-Tolerance class P5 and radial clearance C3
P4 -Tolerance class more accurate than P5
P41-Tolerance class P4 and radial clearance C1
R...- Non-standardized radial clearance (e.g. R45..85)
TN - Polyamide cage
V - Roller bearing without cage (full complement)
VH - Self-retaining roller bearing without cage
W20- Lubrication holes in the outer ring
W518- Lubrication holes in the outer and inner ring
W5- Lubrication groove and holes in both rings
W513-Lubrication groove and holes in the outerring and lubrication holes in the iner ring \mathsf { W } 5 1 3 = \mathsf { W } 3 3 + \mathsf { W } 2 6 （204号
W7 - Locating holes
W8 - Lubrication groove on the outer ring side surfaces
W9 - Lubrication groove on the inner ring side surfaces
W20- Lubrication holes in the outer ring
W33- Lubrication groove and holes on the outer ring
W44- Lubrication groove and holes on the Inner ring
W339-W9 + W33
ZS- NA radial clearance; changing the bearing elements,the clearance can be obtained from the interchangeable elements.

Singleormore rows cylindrical rollerbearings

Singleormore rows cylindricalrollerbearings aremanufacturedby URB in various constructive versions,depending on the position of the ribs on rings.The four basic designs (NU,NJ,Nand NUP) are giveninthe bearing tables.

Bearings of NU design have two fixed ribs on the outerringand one smooth inner ring.Bearings of N design have two fixed ribs on the inner ringand one smooth outer ring.These designs allow an axial displacement incertain limits,of theshaft inrelation to the housing.Therefore,these rolling bearings are used in non-locating bearingunits.

Bearings of NJ design have two fixed ribs on the outer ring and a fixed rib on the inner ring which can guide the shaft ina single direction (axially).

Bearings of NUP design have also two fixed ribs on the outer ringand,on the inner ring,a fixed rib and a support washer.This way they can be used as locating bearings,guiding the shaft axially in both directions.

Fora shaft guiding in a single direction,it also can be used a bearing of NU design which is combined with a support washer.Thus,the constructive version NUJ is obtained.

Support washers on both sides of a bearing of NU designare notallowedas they lead to anaxial blocking of therollers.

Cylindrical rollerbearingscancarry heavyradia loadsand can operateat high speeds.

Doubleor more rows cylindrical roller bearings have small sections,high load carrying capacity and stiffness.

Thesebearingsprovidehighstiffnessand maximum load carrying capacityandare particularly used for tool holders of the machine- tools and roling mills.

Doublerow cylindricalrollerbearingsseries NNU49 and NN3O are generally manufactured to toleranceclassesP5andSP,usedformachinetools

Large-sized bearings seriesNNU49 arealso manufactured to the normal tolerance class.

Cylindrical roller bearings with snap ring groove

Singlerowcylindrical rollerbearingsarealso manufactured with snap ring grooves on the outer rings.This designsimplifies the bearing jointas the bearingsare located into the housingbymeans of the snap rings.The snap ring groove and snap rings are inaccordance with ISO 464,and tables7and 8 on page 90 and 92.

Cylindrical roller bearings without cage (full complement)

These bearings incorporate the maximum number ofrollersand haveasmall sectioninrelationto their width.

This providesa high load carrying capacityand allows space-saving designs to be achieved.

Cylindrical roller bearings without cage cannot beused at speeds as high as those with cages. Thesebearingsaremanufacturedwithsingleor more row rollers and suffix Vis added to the bearing designation.Themostutilizedbearingsare those of series NCF29 V,NCF3OVand NJ23VHand theyare given in this catalogue on page 210.

Dimensions

The main dimensions of standardized bearings givenin tables are inaccordancewith IS015.

Misalignment

The modified contact between rollers and raceway allows not only peripheral stresses to be avoided but also,in case of single row roller bearings,permits an angularmisalignmentof theouterringwithrespect to the innerring，depending on the bearingseries and load according to the table 1.

Tolerancesand radial clearance

Singlerow cylindrical roller bearings are usually manufacturedtonormaltoleranceclasswithnormal radialclearance.They canalso bemanufactured tomore accurate tolerance classesandwith larger (C3NA and C4NA) or smaller (C1NA and C2NA) radial clearances.

Tolerances of cylindrical rollerbearingsare given on pages 28.

Radialclearancesaccordingtointernational standard ISO 5753are givenintales2and3for cylindricalborebearingsbothwithinterchangeable rings and with non-interchangeable rings (NA).

Cages

Small and medium-sized single row cylindrical rollerbearingsare generally fitted withpressed sheet cages.Large-sized bearingsare fitted withmachined brass cages of normal design,i.e.cages of separable design guided on rolling elements M,on the outside surface MA or inner surface MB.In case of heavy loadsand highspeeds,cagesaremade inone piece.

Glassfiber reinforced polyamide6.6cages, are successfully used for small and medium-sized bearings，if theoperatingtemperaturedoesn't e { ⟨ c e d + 1 2 0 ^ { \circ } C . } These cages have lowmass, low coefficient of friction and are noiseless while running.

Cagedesignand some technical dataare given in table 4.

Minimum load

Cylindrical rollerbearingsmustbe subjected toa given minimum load,so that a proper operation of these bearings can be guaranteed.

Thisisnecessaryespeciallyas the bearingsare operatedat high speedsand the centrifugal forces

produce additional friction in bearing due to the sliding between rollers and raceway.

The values of the minimum load can be enough accurately calculated using the equation:

Equivalent dynamic radial load

Forcylindrical roller bearings purely radially loaded which don't locate shafts axially,equivalent dynamic load is:

If cylindrical roller bearings have ribs on the outer and inner rings and locate shafts axially in one or both directions，equivalent dynamic load canbe calculated using the equations:

Where:
e- calculation factorwith values: - 0,2forseries10,2,3 and 4 - 0,3 for series 22,23
Y-factor foraxial load - 0,6 for series10,2,3 and 4 - 0,4 for series 22,23

Cylindricalrollerbearingsaxiallyloadedrun satisfactorilyonlyif theyaresimultaneouslyradially loaded.RatioF/F_should not exceedO,5 for bearings of E designand O,4 for the other bearings.

Equivalent static radial load

Forcylindricalrollerbearingspurelyradially loaded,equivalent static load is:

Dynamic axial load

Bearingswithribsontheouterringcan accommodateaxialloadsinadditiontoradial loads.The axial load carrying capacityof cylindrical rollerbearingsdo not depend essentially onthe steel fatigue strength,but on the resistance of the sliding surfaces at the roller end and rib contactand thereforeon lubrication,operating temperatureand bearing thermal conductivity.

Consideringtheabovementioned，axialload carryingcapacityofacylindrical rollerbearingcan be enough accurately calculated using the following equation:

\mathsf { F } _ { \mathsf { a m a x } } = / { \mathsf { k } _ { 1 } \mathsf { C } _ { 0 r } \mathsf { 1 } 0 ^ { 4 } } { \mathsf { n } ( \mathsf { d } + \mathsf { D } ) } \mathsf { - k } _ { 2 } \mathsf { F } _ { r } , （204号
where:
F - maximumpermissible axial load,kN
a max
\complement _ { \mathfrak { o } _ { \Gamma } } - radial static load,kN
\mathsf { F } _ { { r } } （4 - radial load component,kN
n - operating speed,r/min
d - bearing bore diameter, mm
D - bearing outside diameter, mm
\mathsf { k } _ { 1 } （204号 - auxiliary factor,see table 5
\mathsf { k } _ { 2 } - auxiliary factor, see table 5

Theaboveequationis based on conditionswhich are considered typical for normal bearing operation:

- a difference of 6 0 ^ { \circ } { C } between the bearing operating temperature and the ambient temperature
- a specific heat loss from the bearing of 0 { , } 5 \mathsf { m w /mm ^ { 2 } } ^ { \circ } \mathsf { C } （204号
- aviscosity ratio \scriptstyle \mathsf { k } = 2

Theviscosityratio kis the ratio of the actual viscosityat the operating temperature to the requisite viscosity fora proper lubricationat that temperature. Further details can be found in subchapter“Adjusted rating life”,life adjustment factor \mathtt { a } _ { 2 3 } - 0 \mathtt { n } page 21.

In case of grease lubrication,the base oil viscosity of the grease should be used.These effects can be reduced at low speeds byusing oilswith EPadditives.

The values of permissible axial load \mathsf { F } _ { { a m a x } } obtained from the equation above mentioned are validfor acontinuously acting constant axial load.If axial loadsact only for short periods,the values may be multipliedby2or forshock loads by 3.

The constantly acting axial load \mathsf { F } _ { \mathsf { a m a x } } \left( \mathsf { N } \right) should neverexceed the numerical value of { 1 , 2 \ \mathsf { D } ^ { 2 } } ( \mathsf { D } = bearing outside diameter,mm) and occasional shock loads should never be greater than the numerical value of 3D².

In case of heavy axial loads ( \mathsf { F } _ { \mathsf { a } } > \mathsf { D } ^ { 2 } ) ,the ribs of the outer and inner ring respectively are recommended to be supported by the bearingad joint parts.Bearings of NUP and NJ+HJ designs which take axial loads in both directions are to be placed so that main axial loads should be taken by fixed ribs,if bearing design allows.

Heattreatment

Cylindrical rollerbearingswith outside diameter D > 2 4 0 \ \mathsf {mm } of all series given in the catalogue are tobesubject toa heat treatment of stress relieving which allows bearings to be operated up toa temperatureof + 1 5 0 %

The hardness of rigs should not be less 59 HRC. Small-sized bearings operatenormallyupto + 1 2 0 ^ { \circ } { C }

Abutmentdimensions

Fora proper location of bearing rings on the shaft and housingshoulderrespectively，shaft (housing) maximum radius \rho _ { { u \ m a x } } should be less than bearing minimum mounting chamfer r min

Shoulder height should also be properly sized in case of bearing maximum mounting chamfer.

The values of the connection radius and support shoulder heightare given in table 6.

Abutment dimensions for single row cylindrical rollerbearingsare givenintable7.Thevaluesfor doublerowcylindricalrollerbearingsare givenin table 8.

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159

Single row cylindrical rollerbearings

NJ+HJ

Abutment and fillet dimensions see on page159