Page 161 - needle bearings

Machined ring needle roller bearings, separable Type
NTN

Accuracy of bearing Dimension of oil hole in outer ring
The dimensional accuracy, profile accuracy and The outer ring of bearing Type ZW is provided with an
running accuracy of machined ring needle roller bearing, oil hole and an oil groove to facilitate oil lubrication to
separate type (with inner ring) are specified in JIS B 1514 bearing.
(Accuracy of Rolling Bearings). (Refer to Table 4.3 of Table 1 shows the oil hole dimension every outer ring
Section 4. "Bearing Tolerances" on page A-26.) diameter.
Although the accuracy of NTN standard bearings
conforms to JIS Class-0, NTN can also supply bearings
Table 1 Oil hole dimension
conforming to JIS Class-6, -5 and -4. Feel free to contact
Outer ring outer diameter Oil hole dia. Number of
NTN for the further detail of these bearings.
(mm) oil hole
The dimensional tolerances for the roller inscribed over incl.
circle diameters (Fw) of the bearing type without inner ring ʕ 20 2.0 1
conform to ISO Tolerance Range Class-F6. The outer 20 40 2.5 1
ring and the needle roller and cage assembly are 40 80 3.0 1
supplied in set and, therefore, the bearing must be 80 200 3.5 1
installed with the combination of these two in set
remained unchanged.
Particularly when high bearing accuracy is required, a
bearing with grinding allowance for its inner ring raceway
surface can be supplied upon request from a client. In Mounting relations
that case, however, the client is requested to finish the The inner ring and outer ring of any machined ring
inner ring to the intended dimension after having installed needle roller bearing, separable type must both be
on a shaft. positioned in axial direction by shoulder or a snap ring.
For the shoulder dimension and corner roundness (ra)
of the shaft and the housing are as specified in applicable
Radial clearance and bearing fits
"Dimensions Table". The cage must be guided by the
Table 5.1 of Subsection 5.1 "Radial Clearance in shaft or the side face of the housing shoulder, but the
Bearings" (page A-30) shows the radial clearance of guide surface must be finished by, at least, grinding for
bearings with inner ring. Because of the narrow non- deburring.
interchangeable clearance range, the bearings shipped
after adjusted to a specific non-interchangeable clearance
must be installed with the clearance remained
unchanged.
The respective fitting tolerances for shaft and housing
bore on/in which bearing with inner ring is press-fitted are
per Table 6.3 of 6.4 "Recommended Bearing Fits"
(page A-34) which specifies them according to load
characteristic, load magnitude, and shaft and housing
bore sizes.
The profile accuracy and surface roughness of shaft
and housing to be applied are as specified in Table 7.3 of
7.3 "Shaft and Housing Accuracy" (page A-39).
A shaft is used as the direct raceway surface for a
bearing without inner ring and, in this case, the shaft
diameter (raceway diameter) tolerance is per Table 1
specifying the tolerances according to each running
clearance. And K7 tolerance generally in broad use is
applied as the dimensional tolerance for the housing
bore. Feel free to contact NTN for application of housing
bore tolerance other than K7.
For the profile accuracy, surface roughness and
hardness of a shaft acting as the raceway surface, refer
to Table 7.4 of 7.4 "Raceway Surface Accuracy" (page
A-39).

B-99