Sealed SKF Spherical Roller Bearings – For Demanding Environments

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Sealed SKF spherical roller bearings – for demanding environments

Sealed SKF spherical roller bearings are designed to fulfil high demands on sealing efficiency and operational reli­ability under difficult environmental con­ditions. The seals were developed using computer simulation, making full usage of the vast expertise within the SKF Group. They have been extens­ively tested both in the laboratory and in the field and have proved their reli­able performance and efficiency.

Page ............. 18

SKF sealed spherical roller bearings include double-lip, sheet steel rein­forced seals made of

nitrile rubber (NBR)


hydrogenated nitrile rubber (HNBR)


fluoro rubber (FPM)

and a grease fill which is appropriate to the operating conditions.
This forms a ready-to-mount and lubricated-for-life bearing with long service life and normally the same space requirements as a standard open bearing. The advantages include a simplification of the bearing arrange­ment, as well as the option of down-sizing. Facilities for relubrication are normally not required, and there are no more costs for purchasing, applying and disposing of bearing greases.

Temperature limits
Sealed SKF spherical roller bearings are suitable for normal operating tem­peratures up to 110 °C (230 °F). Bear­ings for higher operating temperatures can be produced upon request. In these cases, the grease and seal material must be chosen accordingly. Other operating conditions such as the speed may need to be considered as well. Please contact the SKF applica­tion engineering service for further advice.

1 Product information
Sealed bearings
Contamination resistance

Due to the efficiency of the integral seals, additional external seals are normally not required. Generally com­pact bearing arrangements can be produced in most cases. However, if the environmental conditions are harsh, external seals should be employed (. fig 1 ).

2 Recommendations
Page ............. 18

Fig 1
A sealed spherical roller bearing in an SNL plummer block housing

3 Product data
Page ............. 32

Warning for fluoro rubber (FPM) seals
FPM is very stable and harmless in normal operating conditions – up to 200 °C (392 °F). However, if exposed to extreme temperatures above 300 °C (572 °F), e.g. fire or the flame of a cutting torch, fluoro rubber emits dangerous toxic vapours. Once overheated the fluoro rubber will remain danger­ous to handle even when cooled. Please contact SKF for complete safety instructions. See also SKF catalog 4006 “CR seals” for further information.

Rule of thumb
Sealed bearings do not need relubrication when the temperat­ures do not exceed 70 °C (158 °F) and speed are not more than 50 % of the speed rating listed in the product tables. More precise in­formation is given in the section “Lubrication and maintenance” on page 28.
Well lubricated
Bearings for normal operating temperat­ures and speeds are lubricated with the SKF lithium base grease LGEP 2 with excellent rust inhibit­ing properties.

Well protected

The bearings have a sheet steel reinforc­ed double-lip seal at each side. Seals can be made of nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR) or fluoro rubber (FPM).
Solid contamin­ants excluded
Eliminate dirt in the bearing, which cre­ates indentations in both raceways and rollers and causes early failure due to flaking. The best and simplest method to do this is to use SKF sealed spherical roller bearings. The seals offer protec­tion for the bearing interior during hand­ling and mounting.

Always reliable
The bearings are filled with a high-quality grease, which is particularly suitable for SKF spherical roller bearings. Integral seals contribute to the efficient lubrica­tion by keeping the lubricant in position inside the bearing.
Moisture cannot enter
Adequate seals keep water out of the bearing, which otherwise would cause corrosion and considerable damage to the raceways, leading to noise and early failure. The im­proved seals are endorsed by the rust inhibiting properties of the lubricant.

Application examples Page ............. 18 Page ............. 32

Efficient in all industrial segments
Industrial segments
• Metallurgical
• Mining & construction
• Pulp & paper
• Fluid machinery
• Materials handling
• Industrial gearboxes
• Textile industry
• Railways

Long service life, high reliability, limited maintenance and the ability to design compact arrangements have made SKF spherical roller bearings indis­pensable in many industries. In addi­tion to the industries listed above SKF spherical roller bearings are also used in bridges, dam gates, electric motors, generators, plastic calenders, ex­truders, printing machines, robots and many other applications.
Because end users are recognizing that high quality bearings deliver an excellent return on investment, SKF spherical roller bearings are becoming the preferred choice in new applica­tions.

Requirements
• 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 support

Where maintenance can be a nightmare
To get to the top is always a challenge, particularly if the goal is the top of ski-lift masts in mid winter when it is 30 de­grees below zero and the bearings have to be relubricated. If operational reliability is to be achieved, then it has to be done. Regular relubrication is a must if the bearings are to be kept from rusting because of condensation. In addition safety considerations call for regular inspections – a dangerous job high up in mountainous terrain and under difficult weather conditions.
The introduction of SKF sealed spher­ical roller bearings has made all the dif-ference. It is now only necessary to per­form maintenance once a season – before starting operation. The highly efficient seals reliably exclude condensa­tion so that corrosion is no longer a problem. It has also been possible to simplify the arrangement, saving space and costs – as well as making handling and installation easier.

Application examples

Downsizing – more than just size
A typical application for spherical roller bearings is the winch of a traversing industrial lift. In this application the load, bending and deformation all call for rugged bearings that can function prop­erly even under misalignment.
Open spherical bearing arrangements provided good service, but were too bulky and complicated to be considered completely satisfactory.

Page ............. 18

As a result, the open bearings were replaced with SKF sealed spherical roller bearings eliminating the need for the external seals and covers.
This obviously saved space and also meant that the bearings could be posi­tioned 40 % closer to the drum, thus reducing the stress on the journals. In fact, it was possible to reduce the jour­nal diameter by 20 % and use smaller bearings.
The new compact bearing arrange­ment requires much less maintenance and there is no loss of load lifting capac­ity. The result has been a 50 % savings of the total cost of the original bearing arrangement.
Page ............. 32

1 Product information
Page ............. 3

Axial location of bearings
An interference fit alone is generally inadequate for the axial location of a spherical roller bearing ring. As a rule, some suitable means of axially secur­ing the ring is needed. Both rings of a locating bearing should be axially secured at both sides. For non-locating bearings, on the other hand, it is suffi­cient if the ring having the tighter fit – usually the inner ring – is axially secured; the other ring must be free to move axially with respect to its seating (. fig 1 on page 21).
Bearing rings having an interference fit are generally mounted so that the ring abuts a shoulder on the shaft or in the housing at one side. At the oppos­ite side, inner rings are normally secured by a snap ring, shaft nut or an end plate attached to the shaft end. Outer rings are usually retained by the housing end cover (. fig 1 on page 21).
An intermediate ring between the bear­ing and lock washer (of the nut) protects the seal
Fig 3

2 Recommendations
Application advice
The dimensions of the shaft and housing shoulders adjacent to the bear­ing must provide sufficient support for the bearing rings, without contact between the rotating parts of the bear­ing and a stationary component. To ensure this, appropriate abutment dimensions are quoted for each indi­vidual bearing listed in the product tables.
When using a shaft nut to locate a sealed bearing, insert an intermediate ring between the bearing and the lock­ing washer and, probably, to extend the threaded portion of the shaft accordingly (. fig 3 ).
Spherical roller bearing of CAK design on a tapered journal with oil supply ducts and grooves
Fig 4

3 Product data
Page ............. 32

Design of associated components
For arrangements with large spherical roller bearings it is often necessary to make design provisions to enable the bearings to be mounted or dismounted 2 easily. For example, withdrawal tools can be applied to dismount bearings, if appropriate slots are machined in the shaft and housing shoulders, or if threaded holes are provided in the housing shoulders.
If the oil injection method is to be used to mount and dismount bearings on tapered journals (. fig 4 ) or to dis­mount bearings from cylindrical seat­ings (. fig 5 ), it is necessary to pro­vide oil supply ducts in the journal and grooves in the seating. Recommenda­tions are given in the SKF publication 4100 “SKF Bearing Maintenance Handbook” or CD-ROM “SKF Inter­active Engineering Catalogue”.
Spherical roller bearing of CA design on a cylindrical seating with oil supply ducts and grooves
Fig 5

Page ............. 3

Grease quantity for periodic relubrication
If the relubrication interval is less than 6 months, it is recommended to re­plenish the grease fill in the bearing arrangement at intervals correspond­ing to 0,5 tf. The complete grease fill should be replaced after three replen­ishments.
Suitable quantities to be added for open bearings can be obtained from
Gp= 0,005 D B
and for sealed bearings from
Gp= 0,0015 D B
where Gp = grease quantity to be added
when replenishing, g D = bearing outside diameter, mm B = total bearing width, mm
The bearing must rotate during relub­rication to achieve proper distribution of the grease.
A polymer band in the annular groove covers the lubrication holes in the outer ring of sealed bearings
Relubrication

Grease quantity for continuous relubrication
The grease quantity to be continuously supplied can be obtained from
Gk= (0,3 ... 0,5) D B × 10–4
where Gk = grease quantity to be continuously
supplied, g/h D = bearing outside diameter, mm B = total bearing width, mm
Continuous relubrication can be effi­ciently achieved using the SKF SYS­TEM 24 lubricator.
Retaining rings hold the seals in the outer ring
Page ............. 32

Relubrication of sealed SKF spherical roller bearings
The sealed spherical roller bearings shown in the product tables (page 54 onwards) have an annular groove and three lubrication holes as standard. To prevent moisture from penetrating and to retain the grease in the bearing a polymer band in the groove covers the lubrication holes (. fig

).

If it is anticipated that bearing relub­rication will be necessary during opera­tion, the band should be removed before the bearing is mounted. When relubricating, grease should be slowly pressed into the bearing as it rotates until fresh grease emerges from the sealing lips. Excess pressure should be avoided to prevent seal damage.

Page ............. 3 Maintenance Page ............. 32

Maintenance
The seals of SKF spherical roller bear­ings with a bore diameter of 110 mm and above are secured by retaining rings inserted in the outer ring (. fig

). The seals can be removed from the bearing so that the bearing can be inspected, washed and regreased, after which the seals can be reinserted and secured. To avoid damage to the seals, this work has to be done with care, using suitable, well rounded tools with no sharp edges.
1. Remove the retaining ring by insert­ing a tool under the recessed end of the retaining ring (. fig ) and pushing it out of the groove.
2.
Remove the second retaining ring as above.
3.
Swivel out the inner ring, so that the seals are pushed out by the rollers.
4.
The bearing, seals and retaining rings can now be washed
5.
Inspect the parts for further usability.
6.
Regrease the bearing with inner ring swivelled out.
7.
Align the bearing and put it on a clean surface for remounting the seals.
8.
Insert the seal as far as possible into its groove in the outer ring. Hold down the already inserted part of the seal with one hand, and press in the remainder, stepwise with the thumb of the other hand (. fig ).
Removing a retaining ring
9. Mount the retaining ring by insert­ing the rectangular end first. Holding this part down, press in the remainder stepwise with a tool, until the whole retaining ring proper­ly contacts the seal as shown in
fig . 10.
Mount the second seal according to steps 7 to 9.
11.
If the bearing is not immediately re-used, preserve the bearing sur­faces with oil and make sure that the bearing is well packed.

Inserting the seal in the outer ring

Page ............. 3 Page ............. 18
Misalignment Axial load carrying capacity
Spherical roller bearings can accom- Because of their special internal design, modate misalignment between the SKF spherical roller bearings not only outer and inner rings without affecting have lower friction than other spherical the bearing. The guideline values of roller bearings, they are also able to permissible misalignment given in accommodate appreciably heavier axial Table refer to open bearings and loads. However, if Fa/Fr > e (. product are valid for normal loads (C/P > 10) tables), a more frequent relubrication and operating conditions, and when than usual is recommended. the inner ring rotates under constant misalignment.

Speed ratings
Whether the stated values of mis- Due to the friction generated by con- alignment between the outer ring and tact seals, the speed ratings for sealed inner ring can be fully exploited or not bearings for normal temperatures are depends on the design of the bearing approximately 40 % of those for the arrangement, the type of seals used etc. corresponding open bearings.

Under the same conditions, sealed SKF spherical roller bearings can accommodate angular misalignments of the shaft with respect to the housing of up to approximately 0,5°.

Influence of operating temperature on the bearing materials SKF spherical roller bearings rings and rollers are special heat treated so that they can be used at temperatures up to +200 °C (390 °F) for up to 2 500 hours or for brief periods at even high­ er temperatures without any inadmiss­ ible dimensional changes occurring.

If provision is made to accommodate slight changes of fits and clearance, even higher temperatures or longer periods can be accommodated.

Sealed SKF spherical roller bearings should not be used at operating tem­ peratures above +110 °C (230 °F) as this would be detrimental to the seals and grease.

Bearing data

Guideline values for permissible angular misalignment

Page ............. 3

Supplementary designations
The designation suffixes used to identi­fy certain features of SKF spherical roller bearings are explained below. The suffixes used to identify bearing (and cage) design, e.g. CC or E, are not included here as they are ex­plained under “Designs”.
C2 Radial internal clearance smaller than Normal
C3 Radial internal clearance greater than Normal
C4 Radial internal clearance greater than C3
C08 Increased running accuracy to ISO tolerance class 5
C083 C08 + C3
C084 C08 + C4
2CS Sheet steel reinforced rubbing seals of nitrile rubber (NBR) at both sides of bearing. Grease fill 25 to 35 % with SKF grease LGEP 2. Annular groove and three lubrication holes in outer ring.
2CSW 2CS + W
2CS2 Sheet steel reinforced rubbing seals of fluoro rubber (FPM) at both sides of bearing. Grease fill 70 to 100 % with a polyurea high temperature grease. Annular groove and three lubrication holes in the outer ring.

2CS2W 2CS2 + W
2CS5 Sheet steel reinforced rubbing seals of hydrogenated nitrile rubber (HNBR) at both sides of bearing. Grease fill 70 to 100 % with a polyurea high temperature grease. Annular groove and three lubrication holes in the outer ring.

2CS5W 2CS5 + W

Page .............18

HA3 Case hardened inner ring
K Tapered bore, taper 1:12
K30 Tapered bore, taper 1:30
VA405 Bearing for vibrating applications
VA406 Bearing for vibrating applications with PTFE-coated bore
VE552(E) Outer ring with three equally spaced threaded holes in one side face to take hoisting tackle; the E indicates that appropriate eye bolts are supplied with the bearings
VE553(E) Outer ring with three equally spaced threaded holes in both side faces to take hoisting tackle; the E indic­ates that appropriate eye bolts are supplied with the bearings
VG186 Hardened cages
VQ424 Running accuracy better than C08
VT143 Grease fill 25 to 35 % with SKF grease LGEP 2
W No relubrication facility in outer ring
W20 Three lubrication holes in outer ring
W26 Six lubrication holes in inner ring
W33 Annular groove and three lubrication holes in outer ring
W77 Plugged W33 lubrication holes
W509 W26 + W33
235220 Case hardened inner ring with helical groove in bore

Bearing data

Page ............. 3 Page ............. 18 Sealed spherical roller bearings d 30 – 130 mm b B

K
r2
r
2
D D1

BS2-22-2CS(2)BS2-22 C-2CS(2)
Principal Basic load ratings Fatigue Speed Mass Designations
dimensions dynamic static load rating Bearings with
limit cylindrical bore tapered bore
d D B C C0 Pu

mm kN kN r/min kg –
30 62 25 56 52 5,5 2 800 0,34 BS2-2206 C-2CS –
35 72 28 76,5 73,5 8 2 400 0,52 BS2-2207 C-2CS –
40 80 28 96,5 90 9,8 2 200 0,57 BS2-2208-2CS BS2-2208-2CSK
45 85 28 90 88 9,5 2 000 0,63 BS2-2209 C-2CS BS2-2209 C-2CSK
50 90 28 96,5 100 11 1 900 0,68 BS2-2210 C-2CS BS2-2210 C-2CSK
55 100 31 125 127 13,7 1 700 1,00 BS2-2211-2CS BS2-2211-2CSK
60 110 34 156 166 18,6 1 600 1,30 BS2-2212-2CS BS2-2212-2CSK
65 100 35 115 173 20,4 1000 0,95 24013-2CS5/VT143 –
120 38 170 183 21,2 1 500 1,60 BS2-2213 C-2CS BS2-2213 C-2CSK
70 125 38 208 228 25,5 1 400 1,80 BS2-2214-2CS BS2-2214-2CSK
75 115 40 152 232 28,5 950 1,55 24015-2CS2/VT143 –
130 38 212 240 26,5 1 300 2,10 BS2-2215-2CS BS2-2215-2CSK
80 140 40 236 270 29 1 200 2,40 BS2-2216-2CS BS2-2216-2CSK
85 150 44 285 325 34,5 1 100 3,00 BS2-2217-2CS BS2-2217-2CSK
90 160 48 325 375 39 1 000 3,70 BS2-2218-2CS BS2-2218-2CSK
100 150 50 248 415 45,5 800 3,20 24020-2CS2/VT143 –
165 52 322 490 53 850 4,40 23120-2CS2/VT143 –
180 55 425 490 49 900 5,50 BS2-2220-2CS –
180 60,3 414 600 63 700 6,70 23220-2CS –
110 170 45 267 440 46,5 900 3,75 23022-2CS –
180 56 430 585 61 800 5,55 23122-2CS2/VT143 –
180 69 460 750 78 630 6,85 24122-2CS2/VT143 –
200 63 560 640 63 800 7,60 BS2-2222-2CS5/VT143 –
120 180 46 355 500 52 850 4,20 23024-2CS2/VT143 –
180 60 430 670 68 670 5,40 24024-2CS2/VT143 –
200 80 575 950 95 560 10,0 24124-2CS2/VT143 –
215 69 630 765 73,5 750 9,75 BS2-2224-2CS –
130 200 52 430 610 61 800 6,10 23026-2CS2/VT143 –
200 69 540 815 81,5 600 7,95 24026-2CS2/VT143 –
210 80 587 1 000 100 530 11,0 24126-2CS2/VT143 –
The designations of Explorer bearings are printed in blue

Page ............. 3 Page .............18

Dimensions Abutment and fillet dimensions Calculation factors
d d2 ˜ D1 ˜ b K r1,2min da min da max Da max ra max e Y1 Y2 Y0
mm mm –

30 36 55,73,721 3636 56 1 0,332 3 2 35 43 63,7 3,7 2 1,1 42 43 65 1 0,31 2,2 3,3 3,2 40 47 73 5,5 3 1,1 47 47 73 1 0,282,4 3,6 2,5 45 53 77,1 5,5 3 1,1 52 53 78 1 0,26 2,6 3,9 2,5 50 58,1 82,1 5,5 3 1,1 57 58 83 1 0,24 2,8 4,2 2,8 55 64 91,9 5,5 3 1,5 64 64 91 1,5 0,24 2,8 4,2 2,8 60 69,3 100 5,5 3 1,5 69 69,3 101 1,5 0,24 2,8 4,2 2,8 65 71,9 92,8 5,5 3 1,1 71,6 71,6 93 1 0,27 2,5 3,7 2,5
74 111 5,5 3 1,5 74 74 111 1,5 0,24 2,8 4,2 2,8 70 80,1 115 5,5 3 1,5 79 79 116 1,5 0,23 2,9 4,4 2,8 75 81,8 105 5,5 3 1,1 81 81,8 109 1 0,28 2,4 3,6 2,5
84,5 119 5,5 3 1,5 84 84,5 121 1,5 0,22 3 4,6 2,8 80 92 1285,5 3 2 91 92 129 2 0,223 4,6 2,8 85 98,21385,5 3 2 96 98 139 2 0,223 4,6 2,8 90 103 148 5,5 3 2 101 103 149 2 0,24 2,8 4,2 2,8 100 108 139 5,5 3 1,5 107 108 143 1,5 0,28 2,4 3,6 2,5 113 152 5,5 3 2 111 113 154 2 0,27 2,5 3,7 2,5 114 160 8,3 4,5 2,1 112 114 168 2 0,24 2,8 4,2 2,8 114 160 8,3 4,5 2,1 112 114 169 2 0,30 2,3 3,4 2,2
110 122 157 8,3 4,5 2 120 122 160 2 0,22 3 4,6 2,8 123 166 8,3 4,5 2 121 123 169 2 0,27 2,5 3,7 2,5 121 163 5,5 3 2 121 121 169 2 0,35 1,9 2,9 1,8 126 182 8,3 4,5 2,1 122 126 188 2 0,25 2,7 4 2,5
120 133 168 5,5 3 2 130 133 170 2 0,20 3,4 5 3,2 130 166 5,5 3 2 130 130 170 2 0,28 2,4 3,6 2,5 132 179 5,5 3 2 131 132 189 2 0,37 1,8 2,7 1,8 136 193 11,1 6 2,1 132 136 203 2 0,26 2,6 3,9 2,5
130 145 186 8,3 4,5 2 140 145 190 2 0,21 3,2 4,8 3,2 141 183 5,5 3 2 140 141 190 2 0,30 2,3 3,4 2,2 142 1905,5 3 2 141142 199 2 0,332 3 2

Page ............. 3 Page ............. 18 Sealed spherical roller bearings d 140 – 220 mm

Principal dimensions Basic load ratings dynamic static Fatigue load limit Speed rating Mass Designation Bearings with cylindrical bore
d D B C C0 Pu
mm kN kN r/min kg –
140 210 225 69 85 570 673 900 1 160 68 112 560 450 8,45 12,7 24028-2CS2/VT143 24128-2CS2/VT143
150 225 250 75 100 655 1020 1 040 1 530 100 146 530 400 10,5 19,5 24030-2CS2/VT143 24130-2CS2/VT143
160 240 270 80 86 750 980 1 200 1 370 114 129 450 530 13,0 26,5 24032-2CS2/VT143 23132-2CS2/VT143
170 260 280 90 109 930 1 280 1 460 1 860 137 170 400 360 17,5 26,5 24034-2CS2/VT143 24134-2CS2/VT143
180 280 100 937 1 730 156 380 23,0 24036-2CS2/VT143
190 320 128 1 600 2 500 212 340 42,0 24138-2CS2/VT143
200 340 140 1 800 2 800 232 320 52,0 24140-2CS
360 128 1 860 2 700 228 430 58,0 23240-2CS2/VT143
220 300 60 630 1 080 93 600 13,0 23944-2CS

The designations of Explorer bearings are printed in blue

Page ............. 3 Page .............18

Dimensions Abutment and fillet dimensions Calculation factors
d d2 ˜ D1 ˜ b K r1,2 min da min da max Da max ra max e Y1 Y2 Y0
mm mm –
140 152 194 5,5 3 2 150 152 200 2 0,28 2,4 3,6 2,5
153 203 8,3 4,5 2,1 152 153 213 2 0,35 1,9 2,9 1,8
150 162 206 5,5 3 2,1 161 162 214 2 0,28 2,4 3,6 2,5
163 221 8,3 4,5 2,1 162 163 238 2 0,37 1,8 2,7 1,8
160 173 218 8,3 4,5 2,1 171 173 229 2 0,28 2,4 3,6 2,5
180 244 13,9 7,5 2,1 172 180 259 2 0,28 2,4 3,6 2,5
170 184 235 8,3 4,5 2,1 181 184 249 2 0,30 2,3 3,4 2,2
185 249 8,3 4,5 2,1 182 185 268 2 0,37 1,8 2,7 1,8
180 195 251 8,3 4,5 2,1 191 195 269 2 0,31 2,2 3,3 2,2
190 210 284 11,1 6 3 204 210 306 2,5 0,40 1,7 2,5 1,6
200 220 300 11,1 6 3 214 220 326 2,5 0,40 1,7 2,5 1,6
227 318 16,7 9 4 217 225 343 3 0,35 1,9 2,9 1,8
220 239 284 8,3 4,5 2,1 231 239 289 2 0,16 4,2 6,3 4

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