Taper Roller Bearings
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The
taper roller bearings can carry combinations of large
radial and thrust loads or thrust load only. Because of the difference
between the inner and outer raceway contact angles, there is a force
component, which drives the tapered rollers against the guide flange. The
relatively large sliding friction generated at this flange makes this
bearing typically unsuitable for high-speed applications without special
consideration to coolant / lubricant. Typical applications include
construction machinery, gear construction, vehicle manufacture and rolling
mills.
Physical Characteristics
- Taper roller bearings have tapered inner and outer ring raceways
between which tapered rollers are arranged.
- The projection lines of all the tapered surfaces meet at a common
point on the bearing axis. Their design makes taper roller bearings
particularly suitable for the accommodation of combined (radial and
axial) loads.
- The axial load carrying capacity of the bearings is largely
determined by the contact angle. The larger the angle, the higher the
axial load carrying capacity.
- Taper roller bearings have the logarithmic contact profile that
provides for optimum stress distribution over the roller/raceway
contacts
- The special design of the sliding surfaces of the guide flange and
large roller ends considerably promotes lubricant film formation in the
roller end/flange contacts.
Advantages Of Taper roller bearings
- Dimensional Stability
- Long Life Even In Contaminated Lubricant
- Durable Steel Cage
- Dimensionally Interchangeable With Other Bearing Manufacturers
Applications Of Taper Roller Bearings
- In many applications taper roller bearings are used in back-back
pairs so that axial forces can be supported equally in either direction.
- Pairs of taper roller bearings are used in car and vehicle wheel
bearings where they must cope simultaneously with large vertical
(radial) and horizontal (axial) forces.
- Agriculture, Construction and Mining Equipment
- Various Axle Systems
- Conveyance Vehicles
- Gear Box, Engine Motors, Reducers
Taper Roller Bearings Design
Tapered roller bearings consist of four basic components including the cone
(inner ring), the cup (outer ring), tapered rollers, and a cage (roller
retainer). Tapered roller bearings are designed such that their conical
rollers and raceways are arranged so that all elements of the roller and
raceway cones meet at a common apex on the bearing axis. The rollers are
guided by the contact between the large end of the roller and the rib on the
inner ring (cone).
This construction provides a high capacity for radial loads, axial loads,
and combined loads. The larger the contact angle, the greater the loading
capacity becomes. When a pure radial load is placed on the bearing, an
induced load in the axial direction is also generated. So, these bearings
are generally used in pairs opposing each other.
Proper running clearance or preload can be obtained by adjusting the
distance of the two bearings against one another. Since the inner (cone) and
outer (cup) rings are separable, each ring can be mounted individually,
allowing both rings to use tight fitting practices, if desired.
Both metric and inch systems are standardized by bearing series and both
systems are widely used. The metric system is specified in ISO (ISO 355) and
JIS 1512, and the inch system (including J-series) is standardized in AFBMA
standard.
Press steel cages are generally used in these bearings, however,
large-sized bearings use machined or pin type cages. Smaller sizes sometimes
use plastic cages depending on the application.
Subunits
Tapered
roller bearings can be disassembled into subunits, that is, the inner ring
with rollers (cone) and the outer ring cup). The subunit dimensions are
standardized in ISO or AFBMA standards. The unified subunits provide
interchangeability within each dimensional standard, Classes 0 and 6X of JIS
for the metric system standards (ISO or JIS); with Classes K, N, and C for
the J-series (AFBMA); and with Classes 4, 2, and 3 for the inch system
(AFBMA). Furthermore, since high precision grade bearings are not
interchangeable these bearings should be used by assembling subunits with
the identical manufacturing number.
Types Of Taper Roller Bearings
The most common types are:
- Single-row tapered roller bearings
- Double-row tapered roller bearings
- Four row tapered roller bearings
Single-row tapered roller bearings
Characteristics
- There are both metric and inch series, and they have been
standardized as shown in the following table.
Dimension series
| |
Metric series |
Inch series |
| Regulations |
· JIS..B 1512
· ISO 355.... |
· ABMA (includes metric
J-series) |
| Basic number |
Example
30210, T2EE040 |
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
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.
- Subunits
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) (Refer to Diagram 2)
- These 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.
- Single row tapered roller bearings are separable, so both the inner
and outer rings can be used with tight fits.
- Tapered roller bearings are also manufactured with flanges attached
to the outer rings. For more details, contact NTN Engineering. (Refer to
Diagram 3)
Specifications & Standards
Dimensions - The boundary dimensions of the drawn cup
needle roller bearings are in accordance with ISO.
Tolerance - They are manufactured to Normal tolerances as
standard. Some are available with reduced width tolerance to tolerance class
specifications.
Misalignment - They are designed to adjust to limited
angular misalignments of the inner ring with respect to the outer to a few
minutes of the arc.
Internal Clearance - The internal clearance for single row
angular contact ball bearing is obtained after mounting and depends on the
second bearingthat provides a location in the opposite direction.
Click here to
View - Total Width Tolerances and Standard Internal Clearance of Taper
Roller Bearings
Minimum load - For satisfactory operation, the bearings
must be subjected to the minimum load that is calculated by
Frm = 0,02 C
where
F
rm , =, minimum radial load, kN
C, =, basic dynamic load rating
Equivalent dynamic bearing load
Equivalent static bearing load
Double-row tapered roller bearings
Characteristics
Back-to-back
arrangement (using double row outer rings) and face-toface arrangement
(using double row inner rings) are both available, and they have been
adjusted so that each type's internal clearance values are fixed.
Therefore, only parts with identical manufacturing numbers can be used
and they must be assembled according to their code numbers. (Refer to
Diagram 4)
- The axial internal clearances for double and duplex bearings are
listed in Table 8, 9 on pages A-58
- Pairs of duplex single row tapered roller bearings are also
manufactured. For more details, contact NTN Engineering.
Double-row tapered roller bearings are used for bearing arrangements
where the load carrying capacity of a single taper roller bearing is
inadequate. They are also used where the shaft is axially located in both
directions with a given positive or negative axial play. Matched bearing
sets provide an economic solution to many bearing arrangement problems and
offer many advantages, including. The matched pairs of the paired bearings
can be provided as
- Face-to-face
- Back-to-back
- In tandem
Advantages
These matched bearings set simplify many problems and are rather
advantageous:
- They allow simple mounting, and mounting errors are avoided
- Exact axial location of the shaft; the axial play is determined
during manufacture
- High radial and axial load carrying capacity
- Easy maintenance
Specifications & Standards
Dimensions - The boundary dimensions of the drawn cup
needle roller bearings are in accordance with ISO.
Misalignment - Misalignment faced by the matched bearings
produces moment load in the bearing thus reducing its life.
Tolerance - They are manufactured to Normal tolerances as
standard.
Minimum load - For satisfactory operation, the bearings
must be subjected to the minimum load that is calculated by:
Frm = 0,02 C
where
F
rm = minimum radial load, kN
C = basic dynamic load rating
Four row tapered roller bearings
Characteristics
As
shown in Diagram 5, four row tapered roller bearings are constructed of
two double row inner rings and two double row outer rings.
- Life of large bearings is extended by using case hardened steel,
hollow rollers and pin-type cages.
- Used primarily where heavy load capacity is important, and in the
roller necks of rolling mills.
