Double row spherical roller bearings with cylindrical and tapered bore
The spherical shape of the raceway in the outer ring enables the misalignment of the rings and ensures balanced distribution of load over the rolling elements even under the slightest shaft deflection, or even when the alignment of the bearing beds is not kept.
These unique parameters enable spherical bearings to:
- reach lower operating temperature and higher rotation speed,
- accommodate higher axial load,
- accommodate higher combined load,
- longer operating life.
The main dimensions of double row spherical roller bearings specified in the dimension tables are in accordance with the international standards ISO 15 (STN 02 4629).
The internal structure of the double row spherical roller bearings utilizes symmetric cylindrical rollers and in dependence on the cage design it has a number of modifications. The design with two-part pressed steel cage, with a floating central collar of the inner ring is marked “E…J” The bearing with a one-part brass cage running on the inner ring is marked “M” and two part brass cage is marked “MB”.
Double-row spherical roller and spherical roller thrust bearings are commonly produced in the basic P0 tolerance class. Production of bearings with a higher tolerance class should be discussed in advance with the manufacturer. The limit values of deviations in tolerances and the operation are specified in ISO 492.
Commonly produced double-row spherical roller bearings have normal radial clearance which is not indicated. In specific cases bearings with radial clearance C2 (smaller than normal clearance) or with the radial clearance C3, C4, C5 (greater than normal clearance) can be produced.
Lubrication groove and holes in the outer ring
In order to ensure better lubrication and higher reliability of the operation double-row spherical roller bearings have a groove and three lubrication holes (W33) in the outer ring.
Bore of the inner ring
Double row spherical roller bearings are produced with a cylindrical or a tapered bore (K), taper 1:12 or 1:30. Bearings with tapered bore are mounted directly to a tapered pivot or to a cylindrical pivot using adapter or withdrawal sleeves in accordance with ISO 2982-1,2.
Stabilisation for operation at higher temperature
For arrangements with operating temperature higher than 120°C specially stabilised double row spherical roller bearings with stabilised shape for operating temperature from 150°C to 400°C (S0, S1, S2, S3, S4 and S5) that are in accordance with ISO 2982-1,2 are produced. Delivery of stabilised bearings should be discussed in advance with the manufacturer.
Double-row spherical roller bearings can misalign from the central position without affecting their correct function.
|Permitted Misalignment||Bearing Type|
|1°30´||222XX, 230XX, 231XX,233XX,239XX|
Axial load ratio of bearings mounted with adapter sleeves
When mounting double row spherical roller bearings to a shaft using adapter sleeves the axial load rating depends on the friction between the shaft and the adapter sleeve. For the properly installed bearings the acceptable axial load can be calculated as follows:
Fap = 3.B.d
Fap – maximum acceptable axial load (N)
B – width of the bearing (mm)
D – diameter of the bearing bore (mm)
Radial equivalent dynamic load
If the bearing is subject to simultaneous radial and axial load, the radial dynamic load is calculated as follows:
Pr = Fr + Y1.Fa for Fa/Fr ≤ e
Pr = 0,67.Fr + Y2.Fa for Fa/Fr > e
Pr – radial dynamic equivalent load (N)
Fr – radial load (N)
Fa – axial load (N)
e,Y1,Y2 – see the table section
Radial equivalent static load
Radial equivalent static load is calculated as follows:
Por = Fr + Y3.Fa
Por – radial static equivalent load (N)
Fr – radial load of the bearing (N)
Fa – axial load of the bearing (N)
Y3 – see the table section
The limiting speed specified in the tables section of the catalogue is the maximum number of revolutions acceptable for the bearing to operate trouble-free at a certain level of safety. Following conditions must be fulfilled:
- bearing load corresponds to the service life L10h =~ 100 000 hours,
- axial forces Fa affecting a radial spherical roller bearing reach max. 25% of the radial force Fr,
- bearings have been produced at the normal level of tolerance class with normal radial clearance,
- limiting speed value for oil lubrication applies to oil-bath lubrication.
The designation of basic designs of the bearings is specified in the dimension tables. Modification of the basic design is designated with additional symbols according to STN 02 4608. The meaning of the most used symbols for double-row spherical roller is in the table.
|K||22208EKW33J||Tapered bore, taper 1:12|
|W33||22311EW33J||Lubrication groove and holes in the outer ring|
|J||22215EW33J||Pressed steel cage, rolling element centred|
|M||22218W33M||Massive brass cage, rolling elements centred|
|E||22319EW33J||Bearing with higher basic load rating|
|P6||22214EW33J P6||Higher tolerance class|
|C2||22309EW33J C2||Radial clearance smaller than normal (normal radial clearance is not indicated)|
|C4||22326KW33M C4||Radial clearance greater than C3|
|S2||22308W33M C5S2||Stabilisation of both rings for operating temperature to 250°C|