>> P.274
Needle Roller Bearings with Thrust Roller Bearing■Identification NumberThe identication number of Combined Type Needle In this series, needle roller bearings are combined Roller Bearings consists of a model code, dimen-with thrust roller bearings to receive thrust loads.sions, any supplemental codes and a classification Their axial load ratings are greater than those of bear-symbol. Some examples are shown below.ings that are combined with thrust ball bearings. Also, elastic deformation of the rolling contact surfaces under load is minimal. Furthermore, the thrust bear-ing section is nished to high accuracy, and therefore high rotational accuracy is obtained in the case of both vertical and horizontal shafts.Like the needle roller bearings with thrust ball bearing, this series also includes bearings with a dust cover and bearings with an inner ring.Needle Roller Bearings with Angular Con-tact Ball BearingIn this series, caged needle roller bearings are com-bined with angular contact ball bearings to receive thrust loads. These bearings conform to the interna-tional dimension series #59, which is based on the ISO Standard. They can withstand heavy radial loads and unidirectional axial loads simultaneously.When the axial load exceeds 25% of the radial load, the radial load will be induced in the angular contact ball bearing, and bearing life will be affected. The relationship between the two loads must therefore be taken into careful consideration.Needle Roller Bearings with Three-point Contact Ball BearingThese bearings can withstand heavy radial loads and bi-directional axial loads at the same time during high-speed rotation.Since the non-interchangeable inner rings are sepa-rated at the center of the ball raceway surface, they must be rmly tightened against the shaft in the axial direction. The axial clearance of this bearing is 0.1〜0.3 mm, and like NATA59, the axial load should not exceed 25% of the radial load.Examples of identication numberExample 1 Model codeDimensionsSupplemental codeClassification symbolNAXI1730ZP6Type of bearingBearing bore diameter(17mm)Assembled bearing width(30mm)With dust coverAccuracy class(Class 6)Example 2 Model codeDimensionsNATA5905Type of bearingDimension seriesBore diameter number■AccuracyDimensional accuracy and rotational accuracy of Combined Type Needle Roller Bearings are based on Table 2 below and Tables 12 and 13 on page A31. The tolerances for the smallest single roller set bore diameter of bearings without inner ring are based on Table 14 on page A33. Thickness variations of thrust rings of NAX(I) and NBX(I) are based on Table 2.4 on page F5.Bore diameter of the small width inner ring of NATB59 is made for a transition t with k5 tolerance shaft.G3
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