plummer block dskatkasndfm

3

Plummer Blocks

1. Structure

Tightening bolt

The bolt protects the plummer block againstloosening due to vibration and impact.

Oil drain plug

For draining old lubricant.

Plummer block unit

Designed for greater mechanical strength, and manufacturedunder strict quality control program. To suit the intendedapplication, it can be made of either spheroidal graphite cast iron(ductile cast iron) or cast steel.

Knock ball

The upper and lower housings can be assembledtogether at higher accuracy thanks to ball-knocksystem using steel balls. Also, the upper covercan be installed or removed easily.

Oil fill plug

For relubrication.

Seal

Excellent sealing performance.

Self-aligning rolling bearing

Self-aligning ball or roller bearing isbuilt into plummer block.

Mounting bolt holes

Allow easy positioningand installation.

Adapter

Simplifies installationof the bearing.

Products painted in user-specified colors s

4

Plummer Block and Rolling Bearing Tolerances

2. Plummer Block and Rolling Bearing Tolerances

2.1 Plummer block tolerancesThe tolerances of NTN split plummer blocks meet JIS B 1551, and those of unit type plummer blocks with Japan Bearing

Manufacturers' Association standard BAS 188. The tolerances of both types are given in the tables below.

Tolerances of bearing seating bore diameter, width and center height ⋯⋯⋯⋯⋯⋯⋯⋯Table 2.1Tolerances of length of cast iron components(As cast portions on bearing base, bolt holes, etc.) ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯Table 2.2Dimensions and tolerances of bore ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯Table 2.3Dimensions and tolerances of stabilizing ring ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯Table 2.4

Plummer block series Plummer blockseries

SN5, SN5FSN (S)6, SN (S)6FSN2, SNZ2, SN30SN (S)3, SNZ (SZ)3, SN31SAF5, SAF6SBG5

SV5SV6SV2SV3SV30SV35VA5

Housingbore

diameter∆Ds

Housingwidth

∆gs

Centerheight

∆Hs

H8 H13 h13

SD30, SD31SD33SD34, SD35SD36SD2, SD3SD5, SD6SD31TS, SD32TS

H8 ±0.2 h13

Housingbore

diameter∆Ds

Centerheight

∆Hs

Bodywidth

I1

Coverdimensions

I2

Coverspigotwidth

I3

H7 h11 ＋0.2　0

±1 　0 －0.2

Unit typeSplit type

Unit: mmTable 2.1 Tolerances of plummer blocks

Casting size

120 or less

±1.5

120 to 250

±2.0

250 to 400

±3.0

400 to 800

±4.0

800 to 1600

±6.0

Unit: mmTable 2.2 Tolerances of length of cast iron components

5


Shaftdiameter

d1 Dimension Tolerance

21.5 26.5 31.5

36.5 41.5 46.5

51.5 56.5 62

67 72 77

82 87 92

102113118

128138143

153163173

183203223

243263283

303323343

363383403

413433453

＋0.210　0

＋0.250　0

＋0.300　0

＋0.350　0

＋0.400　0

＋0.460　0

＋0.520　0

＋0.570　0

＋0.630　0

＋0.250　0

＋0.300　0 ＋0.180

　0

＋0.220　0

＋0.27 0　0

±1˚

＋0.350　0

＋0.400　0

＋0.460　0

＋0.520　0

＋0.570　0

＋0.630　0

＋0.700　0

Dimension Tolerance

313843

485358

678277

828994

99104111

125135140

154164173

183193203

213240260

286306332

352372390

412432452

460480505

Dimension Tolerance

344

444

555

566

667

888

99

10

101010

101111

121213

131314

131314

141414

＋0.140　0

Dimension

4.25.45.4

5.45.45.4

6.96.96.8

6.88.18.1

8.18.19.3

10.810.710.7

12.212.213.7

13.713.713.7

13.715.515.5

17.317.319

191919.8

191920

19.819.820.3

ZF 5ZF 6ZF 7

ZF 8ZF 9ZF10

ZF11ZF12ZF13

ZF15ZF16ZF17

ZF18ZF19ZF20

ZF22ZF24ZF26

ZF28ZF30ZF32

ZF34ZF36ZF38

ZF40ZF44ZF48

ZF52ZF56ZF60

ZF64ZF68GS72

GS76GS80GS84

GS88GS92GS96

202530

354045

505560

657075

808590

100110115

125135140

150160170

180200220

240260280

300320340

360380400

410430450

d2 d3 f1Angular

tolerance

Rubber sealpart number(reference)

f2

Unit: mmTable 2.3 Bore dimensions and tolerances

6


Part number Outsidedia.

h12

Inside dia. Width Material

SR 52× 5SR 52× 6SR 52× 7

SR 52× 9SR 62× 6SR 62× 6.5

SR 62× 7SR 62× 8.5SR 62×10

SR 72× 6SR 72× 7SR 72× 8

SR 72× 9SR 72×10SR 80× 6

SR 80× 7SR 80× 7.5SR 80× 8

SR 80× 9.5SR 80×10SR 85× 6

SR 85× 8SR 85×10SR 90× 6

SR 90× 6.5SR 90× 8SR 90× 9.5

SR 90×10SR100× 6SR100× 8

SR100× 8.5SR100×10SR100×10.5

SR110× 6SR110× 8SR110× 9

SR110× 9.5SR110×10SR110×11.5

SR110×12SR120× 6SR120× 9

525252

526262

626262

727272

727280

808080

808085

858590

909090

90100100

100100100

110110110

110110110

110120120

444444

445454

545454

646464

646470

707070

707075

757580

808080

808989

898989

999999

999999

99108108

5 6 7

9 6 6.5

7 8.510

6 7 8

910 6

7 7.5 8

9.510 6

810 6

6.5 8 9.5

10 6 8

8.51010.5

6 8 9

9.51011.5

12 6 9

Unit: mm

　0 －0.2

Die-castzinc alloy,class 2,ZDC2


h12


SR120×10SR120×12SR120×13

SR125× 9.5SR125×10SR125×13

SR130× 4SR130× 8SR130× 9.5

SR130×10SR130×12.5SR140× 8

SR140× 8.5SR140×10SR140×11.5

SR140×12.5SR140×15SR150× 5

SR150× 9SR150×10SR150×10.5

SR150×14SR150×13SR160× 7

SR160× 9.6SR160×10SR160×11

SR160×11.2SR160×12.5SR160×14

SR160×15SR160×16SR160×16.2

SR170× 4SR170× 9.5SR170×10

SR170×10.5SR170×11.5SR170×14.5

SR170×15SR180× 9.5SR180× 9.7

120120120

125125125

130130130

130130140

140140140

140140150

150150150

150150160

160160160

160160160

160160160

170170170

170170170

170180180

108108108

113113113

118118118

118118125

125125125

125125135

135135135

135135144

144144144

144144144

144144144

154154154

154154154

154163163

101213

9.51013

4 8 9.5

1012.5 8

8.51011.5

12.515 5

91010.5

1413 7

9.61011

11.212.514

151616.2

4 9.510

10.511.514.5

15 9.5 9.7

Unit: mm

　0 －0.2


Table 2.4 (1) Dimensions and tolerances of locating rings

7



h12


SR180×10SR180×12SR180×12.1

SR180×14.5SR180×18SR180×18.1

SR190× 6SR190× 9.5SR190×13.5

SR190×15.3SR200× 9.5SR200×10

SR200×12.2SR200×13.5SR200×14.5

SR200×15SR200×15.8SR200×18.5

SR200×21SR200×22SR210×9.5

SR210×10SR215× 6SR215× 9

SR215× 9.5SR215×10SR215×12

SR215×14SR215×17.5SR215×17.8

SR225× 9.5SR225×10SR230× 6

SR230×10SR230×11SR230×13

SR240× 9.5SR240×10SR240×16

SR240×19.8SR240×23SR250× 5

180180180

180180180

190190190

190200200

200200200

200200200

200200210

210215215

215215215

215215215

225225230

230230230

240240240

240240250

163163163

163163163

173173173

173180180

180180180

180180180

180180190

190195195

195195195

195195195

205205210

210210210

218218218

218218230

101212.1

14.51818.1

6 9.513.5

15.3 9.510

12.213.514.5

1515.818.5

2122 9.5

10 6 9

9.51012

1417.517.8

9.510 6

101113

9.51016

19.823 5

Unit: mm

　0 －0.2



h12


SR250× 6SR250× 9.5SR250×10

SR250×13SR250×15SR260× 9.5

SR260×10SR260×17SR270× 7

SR270× 9.5SR270×10SR270×15

SR270×16.5SR280× 9.5SR280×10

SR280×15SR290× 9SR290×10

SR290×16.5SR290×17SR300× 9.5

SR300×10SR300×11SR310×10

SR310×12SR310×18SR320× 9.5

SR320×10SR320×14SR320×18

SR340× 9.5SR340×10SR340×16

SR340×19SR360×10SR380×10

SR400×10SR500×15.5SR540×18.5

SR580×21.5

250250250

250250260

260260270

270270270

270280280

280290290

290290300

300300310

310310320

320320320

340340340

340360380

400500540

580

230230230

230230238

238238248

248248248

248255255

255268268

268268275

275275290

290290290

290290290

310310310

310330350

370470510

550

6 9.510

1315 9.5

1017 7

9.51015

16.5 9.510

15 910

16.517 9.5

101110

1218 9.5

101418

9.51016

191010

1015.518.5

21.5

Unit: mm

　0 －0.2

Gray castiron,class 3,FC200

Table 2.4 (2) Dimensions and tolerances of locating rings

8


2.2 Machining tolerances of mounting bolt seatfaces

When subjected to a greater lateral load, a plummer blockcannot be reliably secured with the tightening force ofmounting bolts alone. To overcome this problem the endfaces of the mounting bolt seat are secured with stoppersto lock the plummer block. With the plummer block usedin this type of application, the end faces in contact withthe stoppers are machined.When a plummer block mounting seat end faces have

been machined, the bottom length L of the bearinghousing is smaller by the dimension in Table 2.5.

Dimension aftermachining

L,

Tolerance

30～120

±0.8

120～315

±1.2

315～1 000

±2.0

1 000～2 000

±3.0

Unit: mm

Table 2.5 Machining allowance

Table 2.6 Tolerances of dimension L after machining ofmounting bolt seat end faces

Plummer blockpart number

SN506～SN519SN206～SN219SNZ206～SNZ219

SN606～SN616SN306～SN316SNZ306～SNZ316

SV505～SV519SV205～SV219SV605～SV616SV305～SV316

3

5

▽ SN520～ SN220～ SNZ220～

SN617～ SN317～ SNZ317～

Model SN30, model SN31 Model SN..F, model SD

SV520～ SV220～ SV617～ SV317～

Machiningallowance

L-L,

Surfaceroughness

Unit: mm

L: Basic casting dimension (as cast dimension)L': Dimension after machining of the end faces of bearing base

9


2.3 Rolling bearing accuraciesThe tolerances of self-aligning ball and roller bearings

used in conjunction with NTN plummer blocks conform toJIS B 1514 (Tolerances for rolling bearings).

Nominalbore diameter

d

(mm)

Single planemean bore

diameter deviation∆dmp

Single radial plane borediameter variation

Vdp

Mean singleplane bore

diameter deviationVdmp

max

Inner ringradial runout

Kia

max

Inner ringwidth deviation

∆BS

Inner ringwidth variation

VBS

max

diameter series0, 1max

diameter series2, 3, 4max

183050

80120150

180250315400

305080

120150180

250315400500

000

000

0000

101219

253131

38445056

8 911

151919

23263034

8 911

151919

23263034

131520

253030

40506065

202025

253030

30354050

－10－12－15

－20－25－25

－30－35－40－45

over incl. high low

000

000

0000

－120－120－150

－200－250－250

－300－350－400－450

high low

Unit: μm(1) Tolerances of inner rings (JIS class 0)

Nominal outsidediameter

D

(mm)

Single planeoutside diameter

deviation∆Dmp

Single radial plane outsidediameter deviation

VDp

Mean single planeoutside diameter

deviationVdmp

max

Outer ringradial runout

Kea

max

Outer ringwidth deviation

∆Cs

Outer ringwidth variation

VCs

max

diameter series0, 1max

diameter series2, 3, 4max

305080

120150180

250315400

500630

5080

120

150180250

315400500

630800

000

000

000

00

111319

233138

445056

6394

81011

141923

263034

3855

81011

141923

263034

3855

20 25 35

40 45 50

60 70 80

100120

－11－13－15

－18－25－30

－35－40－45

－50－75

over incl. high low

Depends ontolerance of ∆BS relative tod of the samebearing.

Depends ontolerance of VBS relative tod of the samebearing.

high low

Unit: μm(2) Tolerances of outer rings (JIS class 0)

Table 2.7 Bearing tolerances

10


Nominal borediameter

d

(mm)∆dmp ∆dmp - ∆dmp Vdp

max

5080

120

180250315

400500

80120180

250315400

500630

000

000

00

192240

465257

6370

＋15＋20＋25

＋30＋35＋40

＋45＋50

over incl. high low

000

000

00

＋30＋35＋45

＋46＋52＋57

＋63＋70

high low

Unit: μm(3) Tolerance and allowable values (JIS class 0) of tapered 1 bore radial bearings

1 Applicable to all radial planes of tapered boreNote 1: Applicable to 1/12 tapered bore

2: Quantifiersd1 : Standard diameter at theoretical large end of tapered bore

∆dmp : Single plane mean bore diameter deviation at theoretical small end of tapered bore

∆d1mP : Single plane mean bore diameter deviation at theoretical large end of tapered bore

Vdp : Bore diameter variation in a single radial planeB : Nominal bore diameterα : 1/2 nominal taper angle of tapered bore

α= 2˚23'9.4'' 　= 2.38594˚ 　= 0.041643 rad

d1 = d ＋ B121

Theoretical tapered bore Tapered bore associated with singleplane mean bore diameter deviation

11


2.4 Rolling bearing internal clearanceThe radial clearance values of the self-aligning ball

bearings used in the NTN plummer blocks aresummarized in Table 2.8 (1) and (2), and those of theself-aligning roller bearings in Table 2.9 (1) and (2).

Nominal bore diameterd (mm)

Clearance

C2 CN (normal) C3 C4 C5

243040

506580

100

304050

6580

100

120

566

789

10

161819

212427

31

over incl. max min

111314

161822

25

242931

364048

56

max min

192325

303542

50

354044

506070

83

max min

293437

455464

75

465357

698396

114

max min

404650

627689

105

586671

88108124

145

max min

Unit: μm(1) Data for cylindrical bore bearings

Table 2.8 Radial internal clearance of self-aligning ball bearings


Clearance


243040

506580

100

304050

6580

100

120

91214

182329

35

202427

323947

56

over incl. max min

151922

273542

50

283539

475768

81

max min

232933

415062

75

394652

617590

108

max min

334045

566984

100

505965

8098

116

139

max min

445258

7391

109

130

627279

99123144

170

max min

Unit: μm(2) Data for tapered bore bearings

12



Clearance


304050

6580

100

120140160

180200225

250280315

355400450

405065

80100120

140160180

200225250

280315355

400450500

152020

303540

506065

708090

100110120

130140140

303540

506075

95110120

130140150

170190200

220240260

over incl. max min

303540

506075

95110120

130140150

170190200

220240260

455565

80100120

145170180

200220240

260280310

340370410

max min

455565

80100120

145170180

200220240

260280310

340370410

607590

110135160

190220240

260290320

350370410

450500550

max min

607590

110135160

190220240

260290320

350370410

450500550

80100120

145180210

240280310

340380420

460500550

600660720

max min

80100120

145180210

240280310

340380420

460500550

600660720

100125150

180255260

300350390

430470520

570630690

750820900

max min

Unit: μm(1) Data for cylindrical bore bearings


Clearance


304050

6580

100

120140160

180200225

250280315

355400450

405065

80100120

140160180

200225250

280315355

400450500

253040

505565

8090

100

110120140

150170190

210230260

354555

7080

100

120130140

160180200

220240270

300330370

over incl. max min

354555

7080

100

120130140

160180200

220240270

300330370

506075

95110135

160180200

220250270

300330360

400440490

max min

506075

95110135

160180200

220250270

300330360

400440490

658095

120140170

200230260

290320350

390430470

520570630

max min

658095

120140170

200230260

290320350

390430470

520570630

85100120

150180220

260300340

370410450

490540590

650720790

max min

85100120

150180220

260300340

370410450

490540590

650720790

105130160

200230280

330380430

470520570

620680740

820910

1 000

max min

Unit: μm(2) Data for tapered bore bearing

Table 2.9 Radial internal clearance of self-aligning roller bearings

13

Plummer Block and Bearing Materials

3. Plummer Block and Bearing Materials

3.1 Plummer block materialsThe housings of NTN plummer blocks are made of class 3

gray cast iron (FC200). Table 3.1 summarizes themechanical properties of this material.Cast iron materials boasts the greatest vibration

dampening capability among various metal materials.They also perform well in a wider operating temperature

range of –20 to 300˚C.For application involving shock load and vibration, class 2

spheroidal graphite cast iron (FCD450) or class 3 carboncast steel (SC450) is used.

Graycast iron,class 3

Type

FC200

Symbol

13203045

Cast diameterof samples

mm

4 to 8over 8, incl. 15over 15, incl. 30over 30, incl. 50

Typical wall thicknessof cast iron product

mm

235 {24} over216 {22} over196 {20} over167 {17} over

1 960 {200} over4 410 {450} over8 820 {900} over

19 600 {2 000} over

2.0 over3.0 over4.5 over6.5 over

255 incl.235 incl.223 incl.217 incl.

Tensile strength

MPa(kgf/mm2)

Maximum loadN

(kgf)

Flexuremm

Transverse test Brinellhardness

HB

(1) Mechanical properties of gray cast iron

Class 2 spheroidalgraphite cast iron

Type

FCD450

Symbol

450 {46} over 10 over ––––

Tensile strengthMPa

(kgf/mm2)

226 {23} over

Proof stressMPa

(kgf/mm2)

Elongation%

Charpy absorption energyN・m

{kgf・m}

Tensile test Impact test

(2) Mechanical properties of spheroidal graphite cast iron

Carbon cast steel

Type

SC450

Symbol

451 {46} over 19 over 30 over

Tensile strengthMPa

(kgf/mm2)

226 {23} over

Yield point

MPa(kgf/mm2)

Elongation%

Reduction in area%

Tensile test

(3) Mechanical properties of carbon cast steel

Table 3.1 Mechanical properties

14

Plummer Block and Bearing Materials

Accessory

Tightening bolt and nutSpring washerGrease nipple (on housing)Plug for relubrication or drainingStabilizing ring, general purpose(normal width)

Class 2 rolled steel for general structureHard drawn steel wireCopper and copper alloy rod and barClass 2 rolled steel for general structureClass 3 gray cast iron and class 2 zinc die-castingClass 2 rolled steel for general structure

SS400SWRH62BC3604BSS400FC200, ZDC2SS400

G3101G3506H3250G3101G5501, H5301G3101

Material used Symbol Applicable JIS standard

Table 3.2 Plummer block accessories materials

Part description

Bearing bore #14 or smaller

Bearing bore #15 or greater

#05～#07

#08～#32

#34～

Thickness: less than 3 mm

Thickness: 3 mm or greater

Carbon steel for machine structural purposes



Rolled steel for general structure


Cold rolled steel plate and strip



STKM13A

S25C

S20C

SS400

S25C

SPCC-SD

SS400

SS400

G3445

G4051

G4051

G3101

G4051

G3141

G3101

G3101

Can be SS400 (G3101), S20C toS35C (G4051), STPG370 (G3454)or STKM13A (G3445).

Can be SS400 (G3101), orS20C to S35C (G4051).

Can be SPHD (G3131).

Can be S20C to S35C (G4051).

Material used SymbolApplicable

JIS standard Remarks

Sleeve, adapter

Nut

Lock-washer

Lockplate

Table 3.3 Adapter materials

3.2 Bearing materialsRaceway and rolling element materialsWhen the contact surfaces of a bearing raceway and

rolling elements are repeatedly subjected to heavy stress,they still must maintain high precision and runningaccuracy. To accomplish this, the raceway and rollingelements must be made of a material that has highhardness, is resistant to rolling fatigue, is wear resistant, and has good dimensional stability.

By using pure materials, low in these non-metallicimpurities, the rolling fatigue life of the bearing islengthened. For all NTN bearings, pure material isprepared which has low oxygen content and low non-metallic impurities, by vacuum degassing process andsecondary refining process.

Cage materialsBearing cage materials must be strong enough to

withstand the vibration and shock load occurring onrunning bearings, develop limited friction with rollingelements and bearing ring, be light, and resist the heatoccurring on running bearings.The cages for small- and medium-sized bearings are

pressed cages prepared through pressing process withcold or hot rolled steel plate, while the cages for large-sized bearings are machined cages made of cast hightensile brass or carbon steel for machine structuralpurposes.

15

Strength of Plummer Blocks, and Combination with Bearings

4. Strength of Plummer Blocks, and Combination with Bearings

4.1 Strength of plummer blocksThe disruptive strength of plummer block varies

depending on its type, nature and direction of a loadworking on it, as well as the flatness of a surface to whichit is installed. The typical trend of static disruptive strengthof SN5 and SN6 (S6) series of cast iron plummer blocksis plotted in Figs. 4.1 and 4.2 respectively.When selecting a plummer block, the safety factors in

Table 4.1 must be considered. Also, a higher grade offlatness is required of a surface for mounting a plummerblock.

Nature of load

Safety factor

Light

4

Repeated

6

Alternating

10

Shock

15

Table 4.1 Safety factors of cast iron plummer blocks

To counter a horizontal or axial load, the faceof the bed must be secured with a stopper.For applications where extreme shock load is

present or a fractured plummer block can leadto severe accident, NTN offers special plummerblocks made of spherical graphite cast iron orcast steel. For further information, contact NTNEngineering.

Fig. 4.1 Static disruptive strength of SN5 series Fig 4.2 Static disruptive strength of SN6 (S6) series

16


4.2 Combinations of plummer blocks and bearingsThe typical plummer block-bearing combinations are listed in

Tables 4.2 (1) and (2).

Bearing series

SN5SN5‥F

SN(S)6SN(S)6‥F

SN2SN2‥F

SN (S) 3SN (S) 3‥F

SNZ2SNZ2‥F

SNZ (SZ) 3SNZ (SZ) 3‥F

SN30

SN31

SD5SD5‥G

SD6SD6‥G

SD2SD2‥G

SD3SD3‥G

SD2‥DSD2‥DG

SD3‥DSD3‥DG

SD30SD30‥G

SD31SD31‥G

06K～22K

06～22

06～22

12 22 13 23 230 231 222 232 213 223

06K～22

06～22

06～22

06K～22K

06～22

06～22

06K～22K

06～22

06～22

24BK～38BK

34BK～96BK

22BK～38BK

34BK～84BK

08CK～32BK11EK～18EK

08C～32B11E～18E

08C～32B11E～18E

18BK，20BK～32BK

18B，22B～32B

18B，20B～32B

34BK～64BK

34B～64B

34B～64B

08CK～22K

08C～22

08C～22

08CK～32BK

08C～32B

08C～32B

34BK～56BK

34B～56B

34B～56B

Plummer block series

Table 4.2 (1) Plummer blocks and applicable bearings

17


Bearing series

SV5

SV6

SV2

SV3

05K～22K

05～22

12 22 13 23 230 231 222 232 213 223

05K～22K

05～22

05K～22K

05～22

05K～22K

05～22

08CK～64BK11EK～18EK

08C～32B11E～18E

16BK，20B～64B

18B，20B～32B

08CK～22K

08C～22

08CK～22K

08C～56B

Plummer block series

Table 4.2 (2) Plummer blocks and applicable bearings

Example of application with cylindrical roller bearing

Example of application with deep groove ball bearing

18

Allowable Speed

5. Allowable Speed

Greater bearing speed leads to higher bearingtemperature owing to friction heat occurring within thebearing. When the bearing is heated beyond a specificlimit, a bearing failure such as seizure occurs, and thebearing cannot maintain stable operation any more. Thelimiting bearing speed where a bearing can operatewithout developing heat beyond a particular limitation iscalled allowable speed (rpm). This varies depending onthe type and size of bearing, type of cage, as well asloading, lubricating and cooling conditions.The bearing tables in this brochure summarize the

typical allowable bearing speeds either with grease or oillubrication. However, these values assume that:¡An NTN standard design bearing having correct internal

clearance is correctly installed.¡The bearing is lubricated with quality lubricant, and the

lubricant is replenished or replaced at correct intervals.¡The bearing is operated under normal loading

conditions (P≦0.09Cr, Fa/Fr≦0.3), and at a normaloperating temperature.

Note, however, that rolling elements may fail to rotatesmoothly under a load of P≦0.04Cor. For advice againstthis problem, contact NTN Engineering. Also, note thatthe allowable speed of deep groove ball bearing having acontact seal (model LLU) or low-torque seal (model LLH)is governed by the peripheral speed of the seal. Theallowable speed of a bearing that is used under severe

operating conditions can be determined by multiplying theallowable speed of that bearing in a bearing table by anadjustment factor in Fig. 5.1.The allowable speed of a plummer block with a bearing

varies depending on the seal type used. For example, inthe case of a plummer block having a contact seal, itsallowable speed is restricted by the allowable peripheralspeed of the seal. Fig. 5.2 provides a guideline forselecting allowable peripheral speeds of various seals.

Fig. 5.1 Values of adjustment factor f L dependent on bearing load

C: Basic dynamic load rating NP: Dynamic equivalent load N

1 Determine the allowable speed of the seal of a cylindrical bore bearing by referring to the shaft diameter at the contact surface of the seal.In the plotting above, the allowable speeds of the seal are indicated as shaft speeds (rpm).

Fig. 5.2 Allowable speed of bearing vs. allowable peripheral speed of seal no

19

Bearing Seals

6. Bearing Seals

The purposes of bearing seals are to prevent lubricantfrom leaking out and to protect the bearing againstingress of dust and moisture.An appropriate bearing seal is selected considering the

lubricant type (grease or oil) and the peripheral speed ofthe seal.The seal type of NTN plummer blocks can be either

contact or non-contact type. The contact type is availableas felt seals and rubber seals, while the non-contact typeas labyrinth seals. Also, special combination seals areavailable for applications under severe operatingconditions involving, for example, heavy air-borne dust.

6.1 Contact seals(1) Rubber seal (Fig. 6.1)Rubber seals are typically used for grease lubrication,

and their allowable peripheral speed, as a guideline,ranges from 5 to 6 m/s.Usually, the material of rubber seals are nitrile rubber.

However, to cope with demanding ambient temperatures,the materials in Table 6.1 are also available.

(2) Felt seal (Fig. 6.2)Felt seals are compatible with rubber seals, but must be

used for grease lubrication only.Felt seals are not suitable for dusty or moist

environments. Their allowable peripheral speed, as aguideline, is 4 m/s max. A felt seal can be cut into twopieces that are respectively fitted into the seal grooves onthe upper and lower plummer block housings. Thisfeature greatly simplifies the assembly procedure forplummer blocks.

Fig. 6.1 Rubber seal

Fig. 6.2 Felt seal

Seal material

Nitrile rubber (NBR) ◎ ◎ ○ ○ ○ － 25＋100

Features

Wear resistance

Oil resistance

Acid resistance

Alkali resistance

Water resistance

Recom

mended

operatingtem

perature range˚C

Nitrile rubber (NBR) resists virtually all oil types and also features good wearresistance. Thus, this material is most commonly used as an oil seal material.It can be used in ordinary machinery operating under virtually any normaloperating conditions.

Fluororubber (FKM) ◎ ◎ ◎ △ ○ － 10 ＋220

Inert to virtually all oil or chemical types. Its properties are well balanced.Therefore, it features wider operating conditions range. To sum up, this isa superior oil seal material.

Acrylic rubber (ACM) ◎ ◎ △ × △ － 15 ＋130

Boasts excellent heat resistance and oil resistance, but is rather vulnerableto alkali or water. Thus, the scope of its applications is limited.

Silicone rubber (VMQ) ○ ○ △ × ○ － 50 ＋220

Boasts excellent heat resistance and cold resistance. However, it cannot beused together with extreme pressure grease or spindle oil.

◎: Excellent, ○: Good, △: Fair, ×: Poor (must not be used)

Table 6.1 Types and features of rubber seal materials

20

Bearing Seals

Fig. 6.4 Labyrinth seal

Fig. 6.6 Combination seal

Fig. 6.5 Special labyrinth seal

(3) S grease seal (Fig. 6.3)The S grease seal (synthetic rubber seal with spring)

excels in sealing performance and is well suited forgrease or oil lubrication. Custom specification variantscan be used in a plummer block.Its recommended peripheral speed falls within a range

of 10 to 12 m/s. The surface roughness and hardness ofthe shaft in contact with this sealing material necessitatesspecial attention.

6.2 Non-contact seals(1) Labyrinth seal (Fig. 6.4)The labyrinth seal used in the bore of plummer blocks --

SD31…TS and SD32…TS series-- comprise a labyrinthring that is fitted into the bore of the plummer block. Alabyrinth seal is used in clearance fit to a shaft (h9)together with an O-ring so that it can be readily installedand can follow expansion/compression of the shaft.This seal type excels in sealing performance, and can

be used for grease or oil lubrication.

(2) Special labyrinth seal (Fig. 6.5)The special labyrinth seals such as those in Fig. 6.5 are

very useful for applications where heavy soil and dust arepresent.The plummer blocks used in conjunction with this seal

type are manufactured per custom specifications. Forfurther information, contact NTN Engineering.

Shaft design specification for the area in contact with the sealThe quality of a shaft section in contact with the seal lip

greatly affects the sealing performance of the seal.Therefore, strictly adhere to the design standard forshafts in Table 6.2.

6.3 Combination sealsThe combination seals used for the SBG series are

unique seals that comprise both of an oil seal andlabyrinth seal and are installed in the bore of a plummerblock. They are used in environments where heavy dustand contaminants are present.For better sealing effect, the labyrinth seal is often filled

with grease.

With a continuous or intermittent lubricationscheme, lubricant can tend to leak. Use a sealthat positively offers reliable sealing.

Criterion

Hardness HRC30～40

Surfaceroughness

Chamferingat end face

0.8Ra or smaller

The end face to which aseal is fitted must betapered and the sharpcorner must be rounded.

The finish surface shouldbe finish-ground withoutinfeed.

Design standard Remarks

Table 6.2 Shaft design standard

Fig. 6.4 Labyrinth seal

21

Shaft Design

7. Shaft Design

7.1 Bearing-to-shaft fitThe tolerance requirements of the shaft outside

diameter differs between a bearing with an adapter and acylindrical bore bearing each mounted to a plummerblock. Table 7.1 summarizes the recommended bearing-to-shaft fits.A bearing with an adapter is installed to a shaft by

means of an adapter. A cylindrical bore bearing is usuallypositioned in interference fit by a shaft shoulder andsecured with a nut and washer. For this application, theshaft is provided with threading and washer groove asillustrated in Fig. 7.1.

Fig. 7.1

7.2 Mounting dimensionsTo be able to correctly seat a cylindrical bore bearing to

the shaft shoulder, the height and fillet radius ras of theshoulder must be greater than the chamfering rs min of thebearing as specified in Table 7.2.If the bearing is used on the shaft end, the configuration

must be designed such that the shaft end does notinterfere with the face of bearing bore. For reference,Table 7.3 provides the wall thickness values at thebearing bore.

Chamferdimensionrs min mm

11,11,522.12.534567.59.5

2.75 3.5 4.25 5 6 6 7 911141822

111.52222.534568

Shoulderheight h 1

(min)

Fillet radius

ras max

Unit: mm

1 The shoulder height must be greater than that specified when the shaft is subjected to a greater axial load.

Table 7.2 Fillet radius and shoulder height of shaft

H9/IT5All bearing sizesVarious loads

J6k6

over 18, incl. 100over 100, incl. 200

––––––

Light load andfluctuating load

k5m5m6n6p6

over 18, incl. 100over 100, incl. 200

–––––––––

–––over 40, incl. 65over 65, incl. 100over 100, incl. 140over 140, incl. 280

Normal load

n6p6r6

–––––––––

over 50, incl. 100over 100, incl. 140over 140　　　　

Heavy load andshock load

Bearing bore type Load conditionShaft outside diameter Shaft type and

tolerance class RemarksSelf-aligning ball bearing Self-aligning roller bearing

Tapered bore(complete with

adapter assembly)

Cylindrical bore

The tolerance class for transmission shaftsmay be h10/IT7. "IT5" or IT7" means that theshaft form tolerance (circularity, cylidricity,etc.) must satisfy tolerance class IT5 or IT7.

Light load essentially means a load as smallas 6 to 7% the basic dynamic load rating.

Normal load is a load that satisfies0.06Cr＜Pr≦0.12Cr.

Heavy load is a load that satisfies Pr＞0.12Cr.For this type of application, use a bearingwhose clearance is greater than normalclearance.

Pr≦0.07Cr

Table 7.1 Recommended bearing-to-shaft fit

22

Shaft Design

Note: The dimensions for model SN3 are the same as those of model SN2.

Note: For SD31TS and SD32TS, K=37 mm. The dimensions for SD30 and SD31 are the same as those of SD33 and SD34.

SN 506507508509

SN 510511512513515

SN 516517518519520

SN 522524526528530

SN 532

11111111

1114141414

1616161618

2020202323

25

KBearing number

SN 606607608609

SN 610611612613615

SN 616617618619620

SN 622624626628630

SN 632

11111111

1114141414

1616161618

2020202323

25

KBearing number

SN 206207208209

SN 210211212213214

SN 215216217218219

SN 220222224226228

SN 230232

11111313

1314161616

1617171818

2022222223

2325

KBearing number

Unit: mm(1)

(SNZ)

(SNZ)

(SNZ)

(SNZ)

(SNZ)

SD 534536538540544

SD 548552556560564

SD 634636638640644

SD 648652656

4444484854

5258586060

4848545458

586060

KBearing number

SD33403344334833523356

SD33603364336833723376

SD34403444344834523456

SD346034643468

4448485454

5858606060

4848545258

586060

KBearing number

SN30243026302830303032

SN303430363038

SN31223124312631283130

SN3132313431363138

2020222222

242424

2020202222

24242424

KBearing number

Unit: mm(2)

Table 7.3 Wall thickness at the bearing bore

23

Lubrication

8. Lubrication

8.1 Grease lubricationUsually, plummer blocks are lubricated with grease.

Grease lubrication leads to good sealing performanceand simpler seal design.

(1) Characteristics of greaseGrease is prepared by mixing base oil such as mineral

oil or synthetic oil with thickener. The characteristics ofgrease vary depending on types and combination ofvarious additives.The typical grease types and their characteristics are

summarized in Table 8.1.Depending on the intended application, a grease of

appropriate consistency number is used as summarizedin Table 8.2.

(2) Grease volumeWhen grease is packed into a bearing, the inside of the

bearing is first filled with grease. During this course, thegrease must be also filled into the inside guide way of thebearing cage.As a guideline, the recommended volume of grease

filled in plummer blocks is given below.General application

⋯⋯⋯⋯About 1/3 to 1/2 the empty spaceRelatively high speed application

⋯⋯⋯⋯⋯⋯⋯About 1/2 the empty spaceLow speed application

⋯⋯⋯⋯⋯More than 1/2 the empty space

The volume of grease should be carefully selected as itcan lead to overheating of the bearing, outward leakagefrom the seal, or ingress of dust.The recommended volume of grease commonly filled in

the applicable bearings are summarized in Table 8.3.

NLGIconsistency

number

01234

355～385310～340265～295220～250175～205

Centralized lubricationCentralized lubricationGeneral or capped bearingGeneral or high temperatureSpecial application

JIS (ATM)worked

penetrationApplications

Table 8.2 Grease consistency

Bearingnumber

SN3024SN3026SN3028SN3030SN3032

SN3034SN3036SN3038

Bearingnumber

SN3122SN3124SN3126SN3128SN3130

SN3132SN3134SN3136SN3138

260～ 390370～ 550420～ 650

490～ 750 650～1 000

800～1 2001 000～1 5001 000～1 500

Grease volume(g)

260～ 380350～ 550400～ 600470～ 700700～1 000

850～1 300950～1 400

1 100～1 7001 300～2 000

Grease volume(g)

Table 8.3 (3) Volume of grease filled into models SN30 and SN31

Bearingnumber

SN506SN507SN508SN509

SN510SN511SN512SN513SN515


SN522SN524SN526SN528SN530SN532

Bearingnumber

SN606SN607SN608SN609


SN616SN617S618S619S620

S622S624S626S628S630S632

20～ 3030～ 4537～ 5537～ 55

47～ 7055～ 8080～ 120

100～ 150130～ 190

140～ 210170～ 260260～ 390250～ 370330～ 500

470～ 700550～ 850650～ 950800～1 200

1 100～1 6001 300～2 000

Grease volume(g)

27～ 4135～ 5250～ 7575～ 110

100～ 150110～ 160130～ 190160～ 240230～ 350

250～ 380320～ 480370～ 550470～ 700500～ 750

700～1 000950～1 400

1 100～1 6001 300～2 0001 600～2 4001 800～2 700

Grease volume(g)

Table 8.3 (1) Volume of grease filled into models SN5 and SN6

Bearingnumber

SD3340SD3344SD3348SD3352SD3356

SD3360SD3364SD3368SD3372SD3376

SD3440SD3444SD3448SD3452SD3456

SD3460SD3464SD3468

Bearingnumber

SD534SD536SD538SD540SD544



SD648SD652SD656

1 400～ 2 1001 700～ 2 6002 000～ 3 0002 700～ 4 0003 400～ 5 100

3 500～ 5 7004 300～ 6 4005 600～ 8 4006 300～ 9 4006 600～ 9 900

1 500～ 2 2002 300～ 3 4002 300～ 3 5002 700～ 4 0003 200～ 4 800

4 400～ 6 6005 100～ 7 7006 700～1 0000

Grease volume(g)

1 500～ 2 3001 800～ 2 7001 900～ 2 9002 300～ 3 4003 000～ 4 500

3 700～ 5 6004 800～ 7 2006 000～ 9 0006 700～10 0009 300～14 000

1 900～ 2 9002 500～ 3 7002 700～ 4 0003 300～ 5 0003 800～ 5 700

5 400～ 8 1006 500～ 9 8008 700～13 000

Grease volume(g)

Table 8.3 (2) Volume of grease filled into model SD

24

Handling the Plummer Blocks and Bearings

9. Handling the Plummer Blocks and Bearings

Rolling bearings are precision components. To maintaintheir accuracies, they must be handled very carefully. Inparticular, they must be kept clean, not be subjected tostrong impact, and be protected against possible rusting.Plummer blocks also need similar handling practices.

9.1 Inspection before installationBefore installing a bearing and a plummer block, the

following points must be thoroughly checked andinspected.

(1) Prepare installation tools, measuring instruments, oilstone, lubricant and factory cloth. Before theinstallation work, remove dust and impurities fromthese tools. (Fig. 9.1)

(2) Make sure that the shaft is free from bends or otherdamages and that it has been dimensioned andformed as specified. (Fig. 9.2)

(3) Remove dent marks (even though very small) fromthe mating faces with an oil stone or fine emerypaper. Check that the contact face to the seal hasspecified surface roughness (0.8a). Wipe dust awayfrom the shaft with clean factory cloth.

(4) Remove possible dust and metal chips from theinside of plummer block. (Fig. 9.3)

Fig. 9.1

Fig. 9.2

(5) Check the flatness of the mounting face of theplummer block. (When placed on a frame, theplummer block must be stably seated.)

9.2 Preparation for installing the bearing(1) Unpack the bearing just before the installation work.(2) If the bearing is to be grease-lubricated, the rust-

proof coating on it may remain unremoved. If it is tobe oil-lubricated, remove the coating with benzeneor kerosene.

(3) For a bearing with an adapter, check its radialclearance before the installation work. To do so,place it on a flat work bench, and fit a thicknessgage between the uppermost roller and the racewaysurface on the outer ring to measure the clearance(Fig. 9.4). Do not force the thickness gage in or turnthe bearing. Otherwise, the resultant clearancemeasurement will be greater than the actualclearance.

Fig. 9.3

Fig. 9.4

25


9.3 Installation of the bearing and associatedcomponents

Once careful checking is complete, install the bearingand associated components. For the positionalrelationship, see Fig. 9.5.

Fig. 9.6

Fig. 9.5

Fig. 9.7

Fig. 9.8 Press-fitting the inner ring

Fig. 9.9 Simultaneous press-fitting of the inner and outer rings

When a bearing is installed onto a shaft or into ahousing, do not directly hit its end face with a hammeror drift as shown in Fig. 9.6. Otherwise, its designperformance can be lost. Always evenly exert forcearound the entire bearing ring face. Also, do not applyforce to one bearing ring (for example, outer ring) as inFig. 9.7 to convey the force via the rolling elements tothe other bearing ring (inner ring) to install the latter.Otherwise, a dent mark or other damage can occur oneither or both rings.

When installing a cylindrical bore bearing, whoseinterference is relatively small, its whole inner ring canbe uniformly press-fitted at an ordinary temperature asillustrated in Fig. 9.8. Usually, the inner ring is press-fitted by tapping the sleeve with a hammer. However,when many bearings must be installed at a time, amechanical or hydraulic press will be helpful.When installing a non-separable bearing to the shaft

and housing at a time, apply a press-fitting force toboth the inner and outer rings by using a pressuredistribution pad as in Fig. 9.9.

26


9.3.1 Bearing with an adapter(1) Thinly apply highly viscous mineral oil to the taper,

threading and the chamfered face of the nut (seeFig. 9.10) before press-fitting. In particular, applymolybdenum bisulfide paste to these areas on alarge bearing. This prevents scuffing, and allowseasy bearing removal. Before the installation work,remove oil from the shaft and the bore face ofsleeve with a clean factory cloth.

(2) Mount the adapter to a correct position consideringthe dimension B1, B2 or B3 in the bearing table.When fitting the adapter sleeve onto the shaft, open

Fig. 9.10

Nominal bearingbore diameter

d

Reduction of radialinternal clearance

Axial displacement drive up Minimum allowableresidual clearance

Taper 1/12 Taper 1/30over

304050

6580

100

120140160

180200225

250280315

355400450

500560630

405065

80100120

140160180

200225250

280315355

400450500

560630710

0.020.0250.03

0.040.0450.05

0.0650.0750.08

0.090.10.11

0.120.130.15

0.170.20.21

0.240.260.3

0.0250.030.035

0.0450.0550.06

0.0750.90.1

0.110.120.13

0.150.160.18

0.210.240.26

0.30.330.37

0.350.40.45

0.60.70.75

1.11.21.3

1.41.61.7

1.922.4

2.63.13.3

3.744.6

0.40.450.6

0.70.80.9

1.21.41.6

1.71.92

2.42.52.8

3.33.74

4.65.15.7

－－－

－ 1.751.9

2.7533.25

3.544.25

4.7556

6.57.758.25

9.251011.5

－－－

－ 2.252.25

33.754

4.254.755

66.257

8.259.2510

11.512.514.5

0.0150.020.025

0.0250.0350.05

0.0550.0550.06

0.070.080.09

0.10.110.12

0.130.130.16

0.170.20.21

0.0250.030.035

0.040.050.065

0.080.090.1

0.10.120.13

0.140.150.17

0.190.20.23

0.250.290.31

0.040.050.055

0.070.080.1

0.110.130.15

0.160.180.2

0.220.240.26

0.290.310.35

0.360.410.45

min max min max min max CN C3 C4incl.

Unit: mmTable 9.1 Installation of tapered bore self-aligning roller bearings

the slit with a flat-blade screwdriver for easy fitting.FIg. 9.11

(3) Fit the bearing over the adapter sleeve on the shaftas tight as possible, so that the bearing inner ring isfully seated onto the taper on adapter sleeve.

(4) Lightly tighten the nut until the sleeve is seated onthe shaft.

(5) When fully tightening a self-aligning ball bearing,make sure that its radial clearance becomesapproximately 1/2 that before fitting. For a self-aligning roller bearing, tighten the nut whilemeasuring its radial clearance with a thickness gageso that the reduction of radial internal clearancevalue in Table 9.1 is reached. Make sure that aninstalled self-aligning ball bearing can turn smoothlyby hand (ss Figs. 9.12 and 9.13).

Fig. 9.11

27


(6) To tighten the nut, use a spanner wrench illustratedin Fig. 9.14.When tightening the nut with a hammer and a drift,be sure that the chip from the drift does not enterthe bearing.

(7) If it is difficult to tighten a large bearing by manualforce, use a hydraulic nut or ram for easierassembly. (See Fig. 9.15.)

(8) Make sure the bearing clearance is as specified,then bend one tab on the washer that correspondswith the cutout on the circumference of the nut tomaintain the adjustment (Fig. 9.16). Do not loosenthe nut to allow the cutout to match the tab.

(9) When a large bearing is installed to a shaft, its outerring will be deformed by its own weight into anelliptical form. The clearance measurement at thelowest point on a deformed bearing will be greaterthan a true clearance. Remember that a radialclearance value measurement at this point will resultin excessively large tightening allowance.

(10) The adapter used on a large bearing whose borenumber is 44 or greater is a lock plate type (Fig.9.17). For this arrangement, first tighten the nut,then fit the lock plate into the cutout on the nut. Inthis case too, do not loosen the nut to allow thecutout to match the lock plate. Once the lock plate isseated in the cutout, secure the adjustment with aspring washer and a hexagonal nut.Fig. 9.14

Fig. 9.15

Fig. 9.16

Fig. 9.12

Fig. 9.13

28


9.3.2 Cylindrical bore bearing(1) Press-fitting

a. It is recommended that a small bearing of smallertightening allowance be press-fitted by forcing apress-fitting jig onto the end face of inner ring.(See Fig. 9.18.)

b. For easy fitting, apply mineral oil or molybdenumbisulfide lubricant to fitting surfaces on the shaftand bearing. During the press-fitting work, makesure that the bearing inner ring is not tilted.

(2) Shrink-fittinga. To install a medium or large bearing, a shrink-

fitting technique can be conveniently employed.The heating temperature for shrink-fitting can beselected from Fig. 9.19 based on the bearingdimensions and tightening allowancerequirements. Remember the temperature of thebearing must not exceed 120˚C.

b. Usually, the bearing is heated in oil (Fig. 9.20).However, it may be heated in a heater.

c. The oil used as a heating medium is cleanmachine oil #1 or transformer oil #1.The heating oil bath must be amply sized andcontain sufficient amount of oil. Be careful not toallow the bearing to directly contact the vessel.

Fig. 9.17

Fig. 9.18

d. After fitting the bearing onto a shaft, allow it tocool off. Note that the bearing will also shrink inthe axial direction. To avoid gap occurrencebetween the bearing face and the shaft shoulder,force the bearing against the shaft shoulder untilthe bearing and shaft have fully cooled down.Alternatively, tap the bearing several times in theaxial direction through a jig to bring the bearing inclose contact with the shaft before the bearingand shaft have fully cooled down.

e. Make sure the bearing is fully seated on the shaftshoulder. Then, insert the washer and nut overthe shaft, and secure the bearing by tighteningthe nut. Once the nut has been fully tightened,bend a tab on the washer and fit it into the cutouton the nut. If a tab cannot be readily fitted into thecutout, further turn the nut until the tab meets thecutout.

Fig. 9.20

Fig. 9.19

29


9.4 Assembling the plummer blocksWhen installing two or more plummer blocks on a shaft,

use one block to locate the outer ring of a bearing in theaxial direction, and arrange the other block (s) so that theouter ring (s) of bearing (s) in the latter block (s) canmove freely in the axial direction. (See Fig. 9.21.)Once the bearing has been installed to the shaft and the

associated components have been inserted over theshaft, assemble the plummer blocks according to thefollowing procedure.

(1) Temporarily install the lower plummer block housingto the frame. (See Fig. 9.22.)

(2) Fit the locating bearing into the lower plummer blockhousing, together with the seal and stabilizing ring.(See Fig. 9.23.)

(3) Adjust the position of the plummer block of the non-locating bearing to center the bearing to the bearingseating.If the plummer block is to be used in a high temperatureenvironment, carefully position the bearing consideringthe thermal expansion of the shaft.

(4) Once the bearing is correctly located, check thesquareness of the plummer block relative to theshaft (make sure the face of bearing inner ring isparallel with that of the outer ring). Only then, fullytighten the nut. Remember a larger mounting errorcan cause the seal to fail or the shaft to interferewith the bearing bore, leading to non-smoothrunning (Fig. 9.24). If such a problem occurs,correct the mounting seat, and then, install the lowerplummer block housing.

Fig. 9.23

Fig. 9.24

Fig. 9.22

Fig. 9.21

Non-locating side Locating side

Locating side(with one stabilizing ring)

Locating side(with two stabilizing rings)

30


Fig. 9.26

(5) If the bearing is lubricated with grease, fill thebearing interior with grease, and apply grease to themating surfaces of the upper and lower plummerblock housings. Also, amply apply grease to thesliding surface of the seal. In the case of a self-aligning roller bearing, incline the outer ring to allowa sufficient volume of grease to be packed into thegaps between the rollers and the cage. (For thevolume of grease, refer to Section 11.)

(6) In the case of oil-lubricated bearings, fill the oil up to thecenter of the lowest rolling element. (See Fig. 9.25.)

(7) After filling with lubricant, check the mating surfacesbetween the upper and lower plummer blockhousings are stably in contact with each other.Remember to apply grease to the mating surfaceson the plummer block housings to ensure reliablesealing and rust-proofing. Then, fully tighten thetightening bolt. (See Fig. 9.26.)Note that either the upper or lower housing of a

particular plummer block is incompatible with thelower or upper housing of another plummer block.Do not confuse the like housings.Knock pin seats (Fig. 9.27) are provided at the

corners of the bed so locking knock pins can be driveninto these seats. Use these seats when intending toinstall a plummer block with utmost precision.

9.5 Running inspectionOnce the bearing arrangement has been assembled,

make sure the assembly work has been correctlyachieved by following the procedure below.

(1) First, turn the bearing by hand to check that thebearing and seal are free from any irregularities.a. Non-smooth touch: Trapped dust or scratchb. Irregular torque: Abnormal interferencec. Excessively large running torque:

Too small bearing clearance, poor flatness ofmounting seat

(2) Next, run the bearing by power. Begin with no loadand at lower speed.a. Abnormal noise:

Dust, dent mark, or poor lubricationb. Vibration:

Greater misalignment, or excessively largeresidual clearance

(3) Run the bearing under normal operating conditionsto check for temperature rise on the bearing. Thepossible causes to abnormal temperature rise withbearings are as follows:a. Allowable speed has been exceeded.b. Overloadingc. Too small residual clearanced. Negative clearance owing to excessive expansion

or compression with the shafte. Warped plummer block owing to poor flatness

with the mounting seatf. Poor lubrication (excessive or insufficient

lubricant, inappropriate lubrication method oflubricant)

g. Too great tightening allowance for the contactseal, or interference with rotating componentssuch as those around the labyrinth seal

If any irregularity is found as a result of runninginspection, determine and remove the cause. Then,reperform the running inspection to make sure thebearing runs normally.

Fig. 9.25

Fig. 9.27

31


9.6 Maintenance and inspectionTo be able to use a bearing to its design life and avoid

any accident, check the following points at regularintervals.

(1) Running sound on bearing(2) Temperature on bearing or plummer block(3) Vibration on shaft(4) Leaking grease or worn oil seal(5) Loose tightening and mounting bolts(6) Trouble-free operation of the lubrication system, and

loosening or leakage with piping

If the bearing arrangement must be inspected while it isat a standstill, check it for the following points:

(1) Check appearance the of bearing for anyirregularity.

(2) Fouling of grease, or contaminants (dust or steeldust) in grease

(3) Loose adapter sleeve(4) Worn or damaged seal

9.7 Bearing disassembly9.7.1 Bearing with adapterStraighten the bent tab on the washer, and loosen the

nut by two to three turns. Place a drift to a face of the nut.Lightly tap the drift to turn the sleeve (Fig. 9.28). Oncethe sleeve is shifted in the axial direction, the bearing canbe easily removed.Note, however, when the nut has been excessively

loosened and only a few ridges remain engaged, and ifthe nut is further tapped, the threading on the sleeve ornut may be stripped.

9.7.2 Cylindrical bore bearingUsually, a cylindrical bore bearing is interference-fitted.

Thus, the bearing is simply drawn out by placing a jig tothe face of the inner ring and exerting a force asillustrated in Fig. 9.29 with a hand press. However, becareful not to apply a force to the outer ring. A puller suchas that shown in Fig. 9.30 is often used. When using thistool, make sure that the jig is fully engaged with the faceof the inner ring.

Fig. 9.28

Fig. 9.29

Fig. 9.30

32


9.8 Cleaning the bearingClean the removed bearing with diesel oil or kerosene.

Use two vessels: one for rough cleaning and the other forfinish cleaning. Prepare a cleaning station that has ametal screen as illustrated in Fig. 9.31 so that the bearingdoes not directly contact the fouling on the bottom ofvessel. In rough cleaning, virtually all oil and foreignmatters should be removed from the bearing whichshould be immediately transferred to the finish vessel.The finish vessel must be provided with a filter unit tomaintain the cleaning agent clean.Once cleaned, the bearing must be immediately rust-

proofed.The bearings (which have been carefully removed) must

be checked whether they can be reused. The judgingcriterion for reuse should be determined considering thefollowing criteria through a trial-and-error basis.

(1) Scheduled operating duration to next regularinspection

(2) Importance of the machine that uses the bearing inquestion

(3) Operating conditions such as loading and bearingspeed

(4) Severity of damage on the rolling contact surface(5) Tendency of increasing bearing clearance and wear

on the cage(6) Loss in accuracy, etc.

Fig. 9.31

9.9 Storing the bearingWhen storing a bearing, pay particular attention to rust

prevention. Note that the rust-proofing grease in thebearing will run away at a temperature of 50 to 60˚C.Therefore, store a bearing in a dry, cool location at aheight at least 30 cm above the floor. Remember thatwooden crate attracts moisture. Thus, immediatelyunpack the delivered bearings, and store them onshelves.

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