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SKF - Rolling Bearings

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Friction<br />

Table 2a<br />

Geometric and load dependent variables for rolling and sliding frictional moments – radial bearings<br />

Bearing type <strong>Rolling</strong> frictional variable Sliding frictional variable<br />

G rr<br />

G sl<br />

Deep groove ball bearings when F a = 0 when F a = 0<br />

G rr = R 1 d 1,96 m F 0,54 r G sl = S 1 d –0,26 m F 5/3 r<br />

when F a > 0 when F a > 0<br />

q R 2 w<br />

G 0,54<br />

rr = R 1 d 1,96 q S<br />

m F r + JJK F 2 d 1,5 m w 1/3<br />

a G sl = S 1 d –0,145 m F 5 r + JJJK F 4 a<br />

< sin a F z<br />

< sin a F z<br />

a F = 24,6 1F a /C 0 2 0,24 [°]<br />

Angular contact ball bearings 1) G rr = R 1 d 1,97 m 3F r + F g + R 2 F a 4 0,54 G sl = S 1 d 0,26 m 31F r + F g 2 4/3 + S 2 F 4/3 a 4<br />

F g = R 3 d 4 m n 2 F g = S 3 d 4 m n 2<br />

Four-point contact ball bearings G rr = R 1 d 1,97 m 3F r + F g + R 2 F a 4 0,54 G sl = S 1 d 0,26 m 31F r + F g 2 4/3 + S 2 F 4/3 a 4<br />

F g = R 3 d 4 m n 2 F g = S 3 d 4 m n 2<br />

Self-aligning ball bearings G rr = R 1 d 2 m 3F r + F g + R 2 F a 4 0,54 G sl = S 1 d –0,12 m 31F r + F g 2 4/3 + S 2 F 4/3 a 4<br />

F g = R 3 d 3,5 m n 2 F g = S 3 d 3,5 m n 2<br />

Cylindrical roller bearings G rr = R 1 d m<br />

2,41 F r<br />

0,31 G sl = S 1 d m<br />

0,9 F a + S 2 d m F r<br />

Tapered roller bearings 1) G rr = R 1 d 2,38 m 1F r + R 2 Y F a 2 0,31 G sl = S 1 d 0,82 m 1F r + S 2 Y F a 2<br />

For the axial load factor Y for single<br />

row bearings † product tables<br />

Spherical roller bearings G rr.e = R 1 d m<br />

1,85 1F r + R 2 F a 2 0,54 G sl.e = S 1 d m<br />

0,25 1F r<br />

4 + S 2 F a 4 2 1/3<br />

G rr.l = R 3 d m<br />

2,3 1F r + R 4 F a 2 0,31 G sl.l = S 3 d m<br />

0,94 1F r<br />

3 + S 4 F a 3 2 1/3<br />

when G rr.e < G rr.l<br />

G rr = G rr.e<br />

otherwise<br />

G rr = G rr.l<br />

when G sl.e < G sl.l<br />

G sl = G sl.e<br />

otherwise<br />

G sl = G sl.l<br />

CARB toroidal roller bearings when F r < 1R 2<br />

1,85 d m 0,78 /R 1 1,85 2 2,35 when F r < 1S 2 d m 1,24 /S 1 2 1,5<br />

G rr = R 1 d m<br />

1,97 F r<br />

0,54 G sl = S 1 d m<br />

–0,19 F r<br />

5/3<br />

otherwise<br />

G rr = R 2 d m<br />

2,37 F r<br />

0,31<br />

otherwise<br />

G sl = S 2 d m<br />

1,05 F r<br />

The geometry constants R and S are listed in table 3, starting on page 105.<br />

Both loads, F r and F a are always considered as positive.<br />

1) The value to be used for F a is the external axial load.<br />

104

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