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IS0
I N T ERN AT1 ON AL ORGANIZATION FOR STAND A RD IZATl O N
I SO R ECO M M EN DATI O N
R 492
ROLLING BEARINGS
RADIAL BEARINGS
TOLERANCES
1st EDITION
July 1966
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of EO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 492, Rolling Bearings - Radial Bearings - Tolerances, was
drawn up by Technical Committee ISO/TC 4, Rolling Bearings, the Secretariat of which is held
by the Sveriges Standardiseringskommission (SIS).
This IS0 Recommendation cancels and replaces sections 2 and 3 of the IS0 Recommenda-
tion R 15- 1955, Ball and Roller Bearings.
Work on this question by the Technical Committee began in 1949 and led, in 1962,
to the adoption of two Draft IS0 Recommendations :
No. 280, Rolling Bearings. Radial Bearings. Tolerance Classes 6, 5 and 4,
No. 359, Rolling Bearings. Radial Bearings. Normal Tolerances (revision of IS0 Recom-
mendation R 15-1955, Ball and Roller Bearings, section 2).
In May 1962, these Draft IS0 Recommendations were circulated to all the IS0 Member
Bodies for enquiry. They were approved by the following Member Bodies:
Australia Germany Spain
Austria Hungary Sweden
Belgium India Switzerland
Burma Italy United Kingdom
Canada Netherlands U.S.S.R.
Chile New Zealand Yugoslavia
Czechoslovakia Poland
France Romania
Moreover, the Draft IS0 Recommendation No. 359 was approved by the following Member
Bodies :
Brazil, Colombia, Greece, Japan.
One Member Body opposed the approval of Draft IS0 Recommendation No. 280:
Japan
In order to bring all radial bearing tolerances in one document, these two Draft IS0 Recom-
mendations were combined with IS0 Recommendation R 15-1955, Ball and Roller Bearings,
section 3, and then submitted by correspondence to the IS0 Council which decided, in
July 1966, to accept them as an IS0 RECOMMENDATION.
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ISO/R 492 - 1966 (E)
CONTENTS
PW
1. Applicability of the tolerances . 4
2. Symbols . 4
3. Tolerance values . 5
3.1 Normal tolerance class . 5
3.2 Tolerance class 6, . 7
3.3 Tolerance class 5 . 8
3.4 Tolerance class 4 . 9
3.5 Diameter tolerances acceptable after ageing . 10
12
3.6 Normal tolerances for tapered bore, taper 1 : 12 .
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ISO/R 492 - 1966 (E)
IS0 Recommendation R 492 July 1966
ROLLJNG BEARINGS
RADIAL BEARINGS
TOLERANCES
1. APPLICABILITY OF THE TOLERANCES
1.1 This IS0 Recommendation applies to radial rolling bearings, metric series, particularly
those made in accordance with the General Plan for Boundary Dimensions of Radial
Bearings. *
It does not apply to tapered roller bearings.
Attention is called to the fact that different or modified tolerances are or may be recom-
mended for radial bearings of particular types or for particular fields of application.
1.2 Cylindrical bore diameter and outside diameter “not go side” tolerance limits do not
necessarily apply within a distance of twice the nominal ring chamfer dimension from the
ring face.
1.3 The diameter deviations given in Tables 1 to 8 inclusive apply at the time of the final
manufacturing inspection. Subsequent changes in the diameter deviations may occur due
to ageing effects. It is, however, expected that the deviations in tolerance classes 6, 5 and
4 will remain within the values given in Tables 9 and 10. The permissible values of d, and
D, deviations remain unchanged.
1.4 Attention is called to the fact that it is difficult (or sometimes impossible) to make bearings
with shields or seals in the tolerance classes 6, 5 and 4, because the shields and seals influence
the size and shape of the outer ring. For bearings with shields or seals, a widening of the
outside diameter D deviations is recommended.
2. SYMBOLS
d = bearing bore diameter.
d, = arithmetical mean of the largest and the smallest single
diameter of the bore.
D = bearing outside diameter.
Dm = arithmetical mean of the largest and the smallest single
diameter of the outside surface.
B = bearing width (individual inner and outer rings).
* The General Pian is the subject of IS0 Recommendation R , Rolling Bearings - Radial Bearings - Boundary
Dimensions - General Plan, at present Draft IS0 Recommendation No. 358.
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ISO/R 492 - 1966 (E) I
3. TOLERANCE VALUES
3.1 Normal tolerance class
TABLE 1
Inner Ring
Deviations in microns
Cylindrical bore diameter Width B
Bore diameter
(Tolerances KB)
d
Radial
I Variation
nominal run-out of
d**
dm I Deviations
individual
millimetres
ring
Deviations
incl. high low high low max. high low max.
- -
-
2.5 O -8 -9 10 O 40 12
+1
O - 120
10 -8 - 10 10 O 15
+2
18 O -8 -11 O - 120
+3 10 20
- 120
30 O - 10 - 13 13 O 20
+3
- 120
50 O - 12 -15 15 O 20
i-3
- 150
80 O - 15 O
+4 - 19 20 25
- 200
120 O - 20 -25 25 O 25
+5
- 250
180 O - 25 -31 30 O 30
+6
- 300
250 O - 30 -38 40 O 30
i- 8
- 350
315 O - 35 O
+9 - 44 50 35
- 400
400 O - 40 - 50 60 O 40
+ 10
-
- 450
500 O - 45 - 57 65 O
+ 12
- - -
630 O - 50 O - 500
70
- - - -
800 O - 75 O - 750
- - - -
1000 O - 100 O - 1000
- - - -
1250 O -125 O - 1250
-
- - -
1600 O -160 O - 1600
- - - -
2000 O -200 O - 2000
-
* This diameter is included in the group.
** These deviations are valid for two-point measurements only. They apply only to diameter series O, 2, 3 and 4:
in diameter series O, up to and including d = 40 mm,
in diameter series 2, up to and including d = 180 mm.
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ISO/R 492 - 1966 (E)
TABLE 2
Outer Ring
Deviations in microns
~
Outside diameter Width B
Outside diameter
(Tolerances hB1
D
Radial
run-out
nominal
D **
Dm I
Deviations
millimetres
Deviations
max.
over incl. high 10 w high 10 w
-
6 O -8 -9 15
+I
18 O -8 - 10 15
3-2
30 O -9 -11 15
+2
L
Identical to
- 11 - 14 20
50 O
+3
those of inner
O - 13 -17 25
80 +4
ring of same
120 O - 15 - 20 35
+5
bearing
40
150 O - 18 - 24
$6
O - 25 - 32 45
180
+7
O - 30 -38 50
250 +8
315 O - 35 -44 60
+9
70
400 O - 40 - 50
+ 10
80
500 O - 45 + 12 - 57
630 O - 50 - 64
-
800 O - 75
-
1000 O -100
1250 O - 125
(1000)
1600 O -160
(1250)
(1600) 2000 O -200
O -250
(2000) 2500
* This diameter is included in the group,
** These deviations are valid for two-point measurements only. They apply only to diameter series O, 2, 3 and 4:
in diameter series O, up to and including D = 80 mm,
in diameter series 2, up to and including D = 315 mm.
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I
ISO/R 492 - 1966 (E)
3.2 Tolerance class 6
TABLE 3
Inner Ring Deviations in microns
Width B
Bore diameter
Cylindrical bore diameter
d
Radial
Variation
nominal
run-out
d, I d** of
Deviations
individual
millimetres
Deviations ring
~ - -
over incl. high low high low max. high low max.
- -
2.5 O -7 -8 O - 40 12
+1 5
10 O -7 -8 6 O - 120 15
+1
18 O -7 -8 7 O -120 20
+1
30 O -8 -9 8 O -120 20
+1
O - 10
50 -11 10 O -120 20
+1
80 O - 12 - 14
10 O -150 25
+2
120 O
-1
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