Page 119 - needle bearings

Machined ring needle roller bearings
NTN

surface roughness of shaft and housing to be applied are
as specified in Table 7.3 of 7.3 "Shaft and Housing Mounting relations
Accuracy" (page A-39). In the case of raceway with an oil hole, the bearing
A shaft is used as the direct raceway surface for a must be installed so the oil hole locates within the non-
bearing without inner ring and, in this case, the shaft load area. In addition, any bearing with inner ring must be
diameter (raceway diameter) tolerance is per Table 1 used within the allowable stroking value (s) (with the
specifying the tolerances according to each running rollers retained within the effective contact length range of
clearance. And K7 tolerance generally in broad use is inner ring).
applied as the dimensional tolerance for the housing For the allowable stroking value (s), refer to Fig. 1 and
bore. Feel free to contact NTN for application of housing applicable "Dimensions Table".
bore tolerance other than K7. The inner ring and outer ring of machined ring needle
For the profile accuracy, surface roughness and roller bearing must be positioned in axial direction by
hardness of a shaft acting as the raceway surface, refer shoulder or snap ring in this case. For the shoulder
to Table 7.4 of 7.4 "Raceway Surface Accuracy"(page dimension and corner roundness (ra) of the shaft and the
A-39). housing are as specified in applicable "Dimensions
Table".
Table 1 Shaft diameter (raceway diameter) tolerance
Roller inscribed circle dia. Tolerance range class for shaft
Fw
mm Smaller than Ordinary class Larger than s
ordinary
ordinary
Over incl. clearance clearance
80 k5 h5 f6
80 160 k5 g5 f6
160 180 k5 g5 e6
180 200 j5 g5 e6
200 250 j5 f6 e6
250 315 h5 f6 e6
315 400 g5 f6 d6

Fig. 1
Dimension of oil hole in outer ring
The outer ring is provided with an oil hole and an oil
groove to facilitate oil lubrication to bearing. (but
excluding Type NK with roller inscribed circle diameter
(Fw) of 12mm and less.)
Table 2 shows the oil hole dimension every outer ring
diameter.

Table 2 Oil hole dimension
Outer ring outer diameter Number of
Oil hole dia. (mm) oil hole
Over incl.
ʕ 20 2.0 1
20 40 2.5 1
40 80 3.0 1
80 200 3.5 1
200 350 4.0 1
350 ʕ 5.0 1

B-57