Sealed SKF spherical roller bearings – for …

1 1 Product information2 Recommendations3 Product dataSealed bearingsPage .. 18 Page .. 3210 Sealed SKF sphericalroller bearings fordemanding environ-mentsSealed SKF spherical roller bearingsare designed to fulfil high demands onsealing efficiency and operational reli-ability under difficult environmental seals were developedusing computer simulation, making fullusage of the vast expertise within theSKF Group. They have been extens-ively tested both in the laboratory andin the field and have proved their reli-able performance and Sealed spherical roller bearingsinclude double-lip, sheet steel rein-forced seals made of nitrile rubber (NBR) hydrogenated nitrile rubber (HNBR) fluoro rubber (FPM)and a grease fill which is appropriateto the operating forms a ready-to-mount and lubricated-for-life bearing with long service life and normally the samespace requirements as a standardopen bearing . The advantages includea simplification of the bearing arrange-ment, as well as the option of down-sizing.

2 Facilities for relubrication arenormally not required, and there are nomore costs for purchasing, applyingand disposing of bearing limitsSealed SKF spherical roller bearingsare suitable for normal operating tem-peratures up to 110 C (230 F). Bear-ings for higher operating temperaturescan be produced upon request. Inthese cases, the grease and sealmaterial must be chosen operating conditions such as thespeed may need to be considered aswell. Please contact the SKF applica-tion engineering service for information2 Recommendations3 Product dataSealed bearingsPage .. 18 Page .. 32111 Contamination resistanceDue to the efficiency of the integralseals, additional external seals arenormally not required. Generally com-pact bearing arrangements can beproduced in most cases. However, ifthe environmental conditions areharsh, external seals should beemployed( fig).1A Sealed spherical roller bearing in anSNL plummer block housingWarning for fluoro rubber (FPM)sealsFPM is very stable and harmlessin normal operating conditions up to 200 C (392 F).

3 However, ifexposed to extreme temperaturesabove 300 C (572 F), fire orthe flame of a cutting torch, fluororubber emits dangerous toxicvapours. Once overheated the fluororubber will remain danger-ous to handle even when contact SKF for completesafety instructions. See also SKFcatalog 4006 CR seals for of thumbSealed bearings do not needrelubrication when the temperat-ures do not exceed 70 C (158 F)and speed are not more than 50 %of the speed rating listed in theproduct tables. More precise in-formation is given in the section Lubrication and maintenance onpage protectedThe bearings have asheet steel reinforc-ed double-lip sealat each side. Sealscan be made ofnitrile rubber (NBR),hydrogenated nitrilerubber (HNBR) orfluoro rubber (FPM).Well lubricatedBearings for normaloperating temperat-ures and speeds arelubricated with theSKF lithium basegrease LGEP 2 withexcellent rust inhibit-ing reliableThe bearings are filled with a high-quality grease,which is particularlysuitable for SKFspherical rollerbearings.

4 Integralseals contribute tothe efficient lubrica-tion by keeping thelubricant in positioninside the cannotenterAdequate sealskeep water out ofthe bearing , whichotherwise wouldcause corrosionand considerabledamage to theraceways, leadingto noise and earlyfailure. The im-proved seals areendorsed by therust inhibiting properties of the contamin-ants excludedEliminate dirt in thebearing, which cre-ates indentations inboth raceways androllers and causesearly failure due toflaking. The best andsimplest method todo this is to use SKFsealed spherical roller bearings . Theseals offer protec-tion for the bearinginterior during hand-ling and information2 Recommendations3 Product dataApplication examplesPage .. 18 Page .. 32 Where maintenance canbe a nightmareTo get to the top is always a challenge,particularly if the goal is the top of ski-liftmasts in mid winter when it is 30 de-grees below zero and the bearings haveto be relubricated. If operational reliabilityis to be achieved, then it has to be relubrication is a must if thebearings are to be kept from rustingbecause of condensation.

5 In additionsafety considerations call for regularinspections a dangerous job high up inmountainous terrain and under difficultweather introduction of SKF Sealed spher-ical roller bearings has made all the dif-Long service life, high reliability, limitedmaintenance and the ability to designcompact arrangements have madeSKF spherical roller bearings indis-pensable in many industries. In addi-tion to the industries listed above SKFspherical roller bearings are also usedin bridges, dam gates, electric motors,generators, plastic calenders, ex-truders, printing machines, robots and many other applications. Because end users are recognizingthat high quality bearings deliver anexcellent return on investment, SKFspherical roller bearings are becomingthe preferred choice in new in all industrial segmentsIndustrial segments Metallurgical Mining & construction Pulp & paper Fluid machinery Materials handling Industrial gearboxes Textile industry RailwaysRequirements Long service life High load carrying capacity Compact arrangements Tolerant of misalignment Minimum maintenance Reduced operation costs No unplanned stoppages Environmental welfare High availability Technical supportSolutionference.

6 It is now only necessary to per-form maintenance once a season before starting operation. The highly efficient seals reliably exclude condensa-tion so that corrosion is no longer aproblem. It has also been possible tosimplify the arrangement, saving spaceand costs as well as making handlingand installation information2 Recommendations3 Product dataApplication examplesPage .. 18 Page .. 321 Downsizing more thanjust sizeA typical application for spherical rollerbearings is the winch of a traversingindustrial lift. In this application the load,bending and deformation all call forrugged bearings that can function prop-erly even under spherical bearing arrangementsprovided good service, but were toobulky and complicated to be consideredcompletely a result, the open bearings werereplaced with SKF Sealed sphericalroller bearings eliminating the need forthe external seals and obviously saved space and alsomeant that the bearings could be posi-tioned 40 % closer to the drum, thusreducing the stress on the journals.

7 Infact, it was possible to reduce the jour-nal diameter by 20 % and use new compact bearing arrange-ment requires much less maintenanceand there is no loss of load lifting capac-ity. The result has been a 50 % savingsof the total cost of the original information2 Recommendations3 Product dataPage .. 3 Application advicePage .. 32 Fig23 Axial location of bearingsAn interference fit alone is generallyinadequate for the axial location of aspherical roller bearing ring. As a rule,some suitable means of axially secur-ing the ring is needed. Both rings of a locating bearing should be axiallysecured at both sides. For non-locatingbearings, on the other hand, it is suffi-cient if the ring having the tighter fit usually the inner ring is axiallysecured; the other ring must be free tomove axially with respect to its seating( figonpage 21). bearing rings having an interferencefit are generally mounted so that thering abuts a shoulder on the shaft or inthe housing at one side.

8 At the oppos-ite side, inner rings are normallysecured by a snap ring, shaft nut oran end plate attached to the shaft rings are usually retained by thehousing end cover ( figonpage21).11 The dimensions of the shaft andhousing shoulders adjacent to the bear-ing must provide sufficient support forthe bearing rings, without contactbetween the rotating parts of the bear-ing and a stationary component. Toensure this, appropriate abutmentdimensions are quoted for each indi-vidual bearing listed in the using a shaft nut to locate asealed bearing , insert an intermediatering between the bearing and the lock-ing washer and, probably, to extendthe threaded portion of the shaftaccordingly ( fig).3 spherical roller bearing of CA design on a cylindrical seating with oil supply ducts and grooves2 spherical roller bearing of CAK designon a tapered journal with oil supplyducts and groovesDesign of associatedcomponentsFor arrangements with large sphericalroller bearings it is often necessary tomake design provisions to enable thebearings to be mounted or dismountedeasily.

9 For example, withdrawal tools can be applied to dismount bearings ,if appropriate slots are machinedin theshaft and housing shoulders, or ifthreaded holes are provided in the housing the oil injection method is to beused to mount and dismount bearingson tapered journals ( fig) or to dis-mount bearings from cylindrical seat-ings ( fig), it is necessary to pro-vide oil supply ducts in the journal andgrooves in the seating. Recommenda-tions are given in the SKF publication4100 SKF bearing MaintenanceHandbook or CD-ROM SKF Inter-active Engineering Catalogue .54An intermediate ring between the bear-ing and lock washer (of the nut) protectsthe seal3 Fig45 Fig1 Product information2 Recommendations3 Product dataPage .. 3 RelubricationPage .. 3230A polymer band in the annular groovecovers the lubrication holes in the outerring of Sealed bearingsRetaining rings hold the seals in the outer ringGrease quantity for periodic relubricationIf the relubrication interval is less than6 months, it is recommended to re-plenish the grease fill in the bearingarrangement at intervals correspond-ing to 0,5 tf.

10 The complete grease fillshould be replaced after three quantities to be added foropen bearings can be obtained fromGp= 0,005 D Band for Sealed bearings fromGp= 0,0015 D B whereGp= grease quantity to be addedwhen replenishing, gD = bearing outside diameter, mmB = total bearing width, mmThe bearing must rotate during relub-rication to achieve proper distributionof the quantity for continuous relubricationThe grease quantity to be continuouslysuppliedcan be obtained fromGk= (0,3 .. 0,5) D B 10 4whereGk= grease quantity to be continuouslysupplied, g/hD = bearing outside diameter, mmB = total bearing width, mmContinuous relubrication can be effi-ciently achieved using the SKF SYS-TEM 24 lubricator. Relubrication of Sealed SKF spherical roller bearingsThe Sealed spherical roller bearingsshown in the product tables (page 54onwards) have an annular groove andthree lubrication holes as standard. Toprevent moisture from penetrating andto retain the grease in the bearing apolymer band in the groove covers thelubrication holes ( fig).