Single row cylindrical roller bearings
Single row cylindrical roller bearings are able to carry large radial load on a relatively small space. Some applications are able to carry also axial load in one or both directions. Raceways of the outer and inner rings together with the sheet profile of the cylindrical rollers in the shape of ZB allow optimal distribution of the contact pressure in the rolling space. This arrangement also allows advantageous formation of lubrication film between the contact parts of the bearing, optimal rolling, decrease of friction, growth of temperature and therefore lower stress of the junction in the arrangement.
At the same time certain mutual misalignment of the rings is allowed and so the bearings cope better with the real operating conditions and contribute to a better reliability and durability during the operating life of the bearings. Cylindrical Roller Bearings are suitable for arrangements, with high requirements for load transfer in connection with high rotation speed, e. g. machine tools, rolling mills, vehicle axle, etc.
Main dimensions of cylindrical bearings are specified in the dimension tables and they are in accordance the international standards ISO 15.
Cylindrical roller bearings generally consist of two parts – outer or inner ring block on which with the help of cages and guiding ribs cylindrical rollers are fastened and second, separate ring. This arrangement allows separate mounting of rings and so the manipulation of indiviudal parts is made easier. Through the gradual development and introduction of new possibilities in the materials and processing technologies better utilization of the inner bearing space and introduction of application with higher load marked “E” was enabled. Bearings with steel cage are offered in the whole range with higher load. Higher load bearings with brass cage are dependent on technological possibilities and they are indicated in
the table section.
Separate group are bearings with brass cage where rib is joined to the cage body by unriveting of cross pieces. This arrangement allows more efficient utilization of inner bearing space and offers better working properties mainly in connection with durability. Designation of these bearings is done by additional letters „EDM“.
The Following Constructions are the Most Common
The cylindrical rollers are guided by cage between two ribs of outer ring. The inner ring is ribless, which allows mutual bearing rings displacement.
Similar to NU, but inner ring contains a rib on one side. The bearing can accomodate axial force in one direction.
The outer ring is manufactured with two ribs, loose inner ring contains solid rib on one side, from the other side is flat angle ring attached. This type of bearings can be used to carry axial forces in both directions.
The cylindrical rollers are guided by cage in inner ring with two solid ribs. The outer ring is rib less, relative axial bearing rings displacement is possible.
The inner ring with two solid ribs, outer ring with one guiding rib.
Angle rings, which use allows to accomodate axial load from needed direction.
Possible combinations of angle ring HJ with bearings:
We do not recommend the combination of NU bearing with two angle rings, because of axial nipping of rollers can occur.
The illustration of the combinations is above the table chart.
The cylindrical bearings are commonly manufactured within the normal tolerance class P0. Production of bearings with higher tolerance classes is necessary to consult with manufacturer. Limiting values of dimension deviations and operation are stated in the standards ISO 492.
The commonly manufactured cylindrical bearings are with normal radial clearance or with radial clearance C3. For special applications cylindrical bearings can be supplied with radial clearance C2 (smaller than normal) or with clearance C4, C5 (greater than normal and C3). Radial clearance values are in accordance with the standard ISO 5753. These values are
valid for manufactured and unassembled bearing.
Stabilisation for operation at higher temperature
For operating temperature higher than 120°C specially stabilized single row cylindrical roller bearings with stabilized dimensions for operating temperature from 150°C to 400°C (S0, S1, S2, S3, S4, S5) are produced. Delivery of stabilized bearings should be discussed in advance.
The inner construction of area of rolling contact allows the operation of cylindrical bearings with a certain misalignment of both rings.
The standard values are:
4´ – for bearing series 2, 3
3´ – for bearing series 22, 23
Cylindrical bearings are generally produced with cages running over the rolling components in following versions:
E – pressed steel cage, consisting of 2 ribs and cross pieces, joined by unriveting of pins
M – massive brass cage, which rib is joined to the shell by steel pins
EM – similar cage as M, but in construction with higher load
EDM – massive brass cage, where rib is to the cage body joined by unriveting of cross pieces
TNG, ETNG – a single cage made of polyamide PA 6.6, reinforced by 25 % content of glass fibres, delivered mostly in more bearing ETNG version. Availability of cages in other versions must be consulted with the manufacturer in advance.
Equivalent dynamic load
If cylindrical bearings are used to convey only the radial load rating without the axial load, dynamic load is calculated as follows:
Pr = Fr
If the cylindrical bearing is subject to simultaneous radial and axial load, the dynamic load is calculated as follows:
Pr = Fr for Fa/Fr ≤ e
Pr = 0,92.Fr + Y.Fa for Fa/Fr > e
e = calculation coefficient
e = 0,2 for bearing series 2, 3, 4
e = 0,3 for bearing series 22, 23
Y = axial load coefficient
Y = 0,6 for bearing series 2, 3, 4
Y = 0,4 for bearing series 22, 23
For trouble free operation of cylindrical bearings, which convey the axial load, there is important to achieve radial load, where ratio Fa/Fr should not exceed the value 0,5.
Equivalent static load
For static loaded cylindrical bearings is valid:
Por = Fr
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.
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 cylindrical roller bearings is in the table:
|M||NU210M||Massive brass cage, with steel pins|
|E||NU210E||Bearing with higher basic load ratio and steel cage|
|EM||NU310EM||Bearing with higher basic load ratio and with steel pins joined brass cage|
|EDM||NU210EDM||Bearing with higher basic load ratio and brass pin less cage|
|P6||NU210E P6||Higher tolerance class|
|C2||NU210E C2||Radial clearance smaller than normal (normal radial clearance is not indicated)|
|C3||NU210E C3||Radial clearance greater than normal|
|S1||NU210E S1||Stabilisation of both rings for higher operating temperature|
Combination of symbols
|NJ+HJ||NH210E||Bearing NJ with angle ring HJ|
|P6+C3||NU210E P63||Bearing with higher tolerance class than standard and radial clearance greater than normal|