NTN tapered roller bearings are designed so the inner and outer ring raceway and the apex of the tapered rollers intersect at one point on the bearing centerline. For this reason, the rollers are pushed against the inner ring rib and roll guided by the rib, receiving the loads from the inner ring raceway surface and the outer ring raceway surface as a combined load on the raceway surface.
Component force is produced in the axial direction when a radial load is applied, so the bearings must be used in pairs. The inner ring with rollers and outer ring separate, facilitating mounting with clearance or preload. However, assembled clearance is hard to manage and calls for attention. Tapered roller bearings are capable of supporting large loads, both axial and radial.
NTN tapered roller bearing have both metric and inch series, and they have been standardized as shown in the following table.
|Metric series||Inch series|
JIS B 1512
|ABMA (includes metric J-series)|
|Inner ring no. / outer ring no. ("J" appears at the beginning of the basic number in the case of J-series.)|
* Dimension series previously not covered by 3XX are regulated under JIS B 1512; dimensions previously missing from 3XX will henceforth use the NTN bearing number.
In addition to level type, there are also medium contact angle and large contact angle types, and the contact angle code C and D, respectively, is appended to the basic numbers of the latter two types.
NTN tapered roller bearings can be disassembled into parts .. the inner ring, rollers, and cage (collectively known as the "cone") .. and the outer ring (known as the "cup"). These are the bearing¡¯s "subunits". Subunit dimensions are standardized under ISO or ABMA standards, and unified subunits are interchangeable within each dimensional standard. However, high precision grade bearings are generally not interchangeable, and these subunits must be used by assembling only subunits with identical manufacturing numbers.
Aside from any cautionary notes that may appear, the single row tapered roller bearings listed in the dimension tables have subunits standardized for both metric and inch systems (including J series).
These NTN bearings are constructed to have a high capacity for radial loads, axial loads, and combined loads. The larger the contact angle, the greater the axial load capacity becomes. When a pure radial load is placed on the bearings, an induced load in the axial direction is also generated, and so these bearings are generally used in pairs arranged face to face.
When used in pairs, proper internal clearances and preload can be set by adjusting the distance between the two bearings' inner and outer rings.
NTN single row tapered roller bearings are separable, so both the inner and outer rings can be used with tight fits.