Page 37 - needle bearings

Bearing Fits
NTN

6.4 Recommended Fits diameter and bearing outer diameter.
The dimensional tolerances for the diameter of a shaft Table 6.2 shows the recommended fits for the
and the hole diameter of a bearing housing, on/in which a machined ring needle roller bearings (with inner ring) that
bearing is installed, are standardized under the metric are generally selected based on the dimensional and load
system in ISO 286 and JIS B 0401 (Dimensional conditions. Table 6.3 shows the numerical fit values.
Tolerances and Bearing Fits). Hence, bearing fits is For the recommended fits for others than the
determined by selection of the dimensional tolerances for machined ring needle roller bearings, refer to
shaft diameter and hole diameter as applicable. Fig. 6.1 "Commentary" described in the respective Dimension
shows the relationship between shaft diameter and Tables.
bearing bore diameter and between housing hole

ʴ50Жm ʴ50Жm
F7
p6 F6
n6 G7
m6 G6 H7
k6 m5
k5 H6 JS7
js5 JS6
h5 K6 K7
0 0
϶dmp ϶Dmp
h6 js6
g5 M6
g6 M7 N6
f6 N7 P6 P7
R7
ʵ50Жm ʵ50Жm

Fig. 6.1 (a) Bearing fits on shaft Fig.6.1(b) Bearing fits in housing hole

Table 6.2 Machined ring needle roller bearing fits
Table 6.2 (1) Dimensional tolerance for shaft diameter Table 6.2 (2) Dimensional tolerances for housing
Conditions Tolerance Tolerance
Shaft diameter d range class Conditions range class
Load characteristic Load magnitude
mm
Light load ʙ 50 j5 Ordinary and heavy load J7
Outer ring static load
ʙ 50 k5 Two-split housing, ordinary load H7
Rotating inner ring Ordinary load 50ʙ150 m5 Light load M7
load or directionally
unstable load 150ʙ m6 Rotating outer ring load Ordinary load N7
ʙ150 m6 Heavy load and shock load P7
Heavy load and
shock load 150ʙ n6 Light load J7
Medium- and low-speed Directionally unstable load Ordinary load K7
rotation, light load g6
Heavy load and shock load M7
Inner ring static All dimensions
load General application h6 When high rotational accuracy under light load is required K6
When high rotational h5 Remarks: Light load, ordinary load and heavy load are classified per the
accuracy is required
following criteria.
Light load : Prʽ0.06Cr
Ordinary load : 0.06Cr< Prʽ0.12Cr
Heavy load : Pr>0.12Cr

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