Cylindrical roller bearings with disc cage/with spacers are suitable where:
- Bearing arrangements are subjected to very high radial loads and higher speeds occur ➤ section, ➤ section
- High dynamic inertia forces are present
- Not only high radial forces but also axial loads from one direction must be supported by the bearing position (semi-locating bearing function) ➤ section
- High shock loads occur
- Thermally stable conditions are required in the bearing even at higher speeds
- The cages are subjected to high dynamic inertia forces; e. g. in vibratory machinery
- Axial displacements of the shaft relative to the housing must be compensated without constraint in the bearing
- The bearings should be separable for easier mounting; in vibratory machinery, for example, the bearing ring with circumferential load as well as the ring with point load should have a tight fit ➤ section, ➤ section
Cylindrical roller bearing with full complement bearing/standard cage/disc cage, comparison of speed and load carrying capacity
nG = limiting speed
Cr = basic dynamic load rating
SL1923 = full complement cylindrical roller bearing
NJ23 = cylindrical roller bearing with standard cage
LSL1923 = cylindrical roller bearing with disc cage
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Design variants
These cylindrical roller bearings are available as:
- type LSL1923 (bearing with disc cage) ➤ Figure
- type ZSL1923 (bearing with spacers) ➤ Figure
- special design for vibratory machinery ➤ link
- X-life bearings ➤ link
Basic design – standard range
LSL1923 and ZSL1923 correspond to dimension series 23
Cylindrical roller bearings with disc cage or with spacers are part of the group of radial roller bearings and correspond to dimension series 23. These single row bearings comprise radially split outer rings, removable inner rings, disc cages or spacers and cylindrical rollers. The rollers have profiled ends, i. e. they have a slight lateral curvature towards the ends. This modified line contact between the raceways and rolling elements prevents damaging edge stresses ➤ Figure. For mounting of the bearings, the inner ring can be removed.
Series LSL1923 – bearings with disc cage
Bearings with semi-locating bearing function
Cylindrical roller bearings LSL1923 have two rigid ribs on the outer ring and one rigid rib on the inner ring. An externally-guided flat brass disc cage prevents the rolling elements from coming into contact with each other during rolling ➤ Figure and ➤ section. The disc cage has pockets in which the rolling elements run. The rollers are guided between the ribs on the outer ring. The outer ring is axially split and held together by fasteners. Due to their design configuration, the bearings permit axial displacements of the shaft relative to the housing in one direction. In the opposite direction, they act as locating bearings. The maximum axial displacement s is given in the product tables.
Cylindrical roller bearing with disc cage
Fr = radial load
Fa = axial load
Brass disc cage
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Series ZSL1923 – bearings with spacers
Bearings with semi-locating bearing function
In the case of cylindrical roller bearings ZSL1923, plastic spacers prevent the rollers from coming into contact with each other during rolling ➤ Figure and ➤ section. The spacers are guided axially between the ribs on the outer ring. They are designed such that the rolling element set is self-retaining, so the outer ring with the rolling element set and the inner ring can be mounted separately from each other. Due to their design configuration, the bearings permit axial displacements of the shaft relative to the housing in one direction. In the opposite direction, they act as locating bearings. The maximum axial displacement s is given in the product tables.
Cylindrical roller bearing with spacers
Fr = radial load
Fa = axial load
Plastic spacers
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Special design of bearings LSL and ZSL for vibratory machinery
In addition to high basic dynamic load ratings Cr (and thus long rating life values), bearings for vibratory machinery must also be able to compensate or support considerable shaft tilting due to load or misalignment. The cylindrical roller bearings LSL and ZSL are therefore also available by agreement in the BIR design ➤ Table. In these bearings, the inner ring raceway is ground slightly spherical.
X-life premium quality
Many sizes of the bearings are also available as X-life bearings. These bearings exhibit considerably higher performance than comparable standard cylindrical roller bearings. This is achieved, for example, through the modified internal construction, the optimised contact geometry between the rollers and raceways, better surface quality and the optimised roller guidance and lubricant film formation.
Increased customer benefits due to X-life
These technical enhancements offer a range of advantages, such as:
- a more favourable load distribution in the bearing and thus a higher dynamic load carrying capacity of the bearings
- a higher fatigue limit load
- lower heat generation in the bearing
- lower lubricant consumption and therefore longer maintenance intervals if relubrication is carried out
- a measurably longer operating life of the bearings
- high operational security
- compact, environmentally-friendly bearing arrangements
Interchangeable with comparable standard bearings
Since X-life cylindrical roller bearings have the same dimensions as the corresponding standard bearings, the latter can be replaced without any problems by the higher-performance X-life bearings. The major advantages of X-life can therefore also be used for existing bearing arrangements with standard bearings.
Lower operating costs, higher machine availability
In conclusion, these advantages improve the overall cost-efficiency of the bearing position significantly and thus bring about a sustainable increase in the efficiency of the machine and equipment.
Suffix XL
X-life cylindrical roller bearings include the suffix XL in the designation ➤ section and ➤ link.
X-life indicates a high product performance density and thus a particularly significant benefit to the customer.
Designed for high radial loads
Cylindrical roller bearings LSL and ZSL are used as semi-locating bearings. These bearings can support not only high radial forces but also axial forces in one direction; i. e. they can guide the shaft axially in one direction. Furthermore, they can withstand high shock loads, vibrations and accelerations.
Higher basic dynamic load ratings lead to an increase in basic rating life
Due to the internal construction, the bearings can acommodate more rolling elements than conventional cylindrical roller bearings. As a result, there is a significant increase in the basic dynamic and static load rating and thus the basic rating life compared with conventional cylindrical roller bearings. ➤ Figure shows a comparison of the basic dynamic load rating Cr between a cylindrical roller bearing NJ2324 with a conventional cage, a bearing with a disc cage and a bearing with spacers. The advantage in basic dynamic load rating of approx. 14% gives an increase in the basic load rating of approx. 55% ➤ Figure.
Comparison of basic dynamic load ratings – conventional cylindrical roller bearing NJ2324 with LSL192324 and ZSL192324
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Comparison of basic percentage rating life – conventional cylindrical roller bearing NJ2324 with LSL192324 and ZSL192324
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Higher axial load carrying capacity of bearings with toroidal crowned roller end face
Neither wear nor fatigue occurs on the rib contact running and roller end faces
In the case of cylindrical roller bearings with toroidal crowned rollers (TB design), the axial load carrying capacity has been significantly improved with the aid of new calculation and manufacturing methods. A special curvature of the roller end faces facilitates optimum contact conditions between the rollers and ribs ➤ Figure. As a result, the axial contact pressures on the rib are significantly minimised and a lubricant film capable of supporting higher loads is formed. Under standard operating conditions, this completely eliminates wear and fatigue at the rib contact running and roller end faces. In addition, the frictional torque is reduced by up to 50%. The bearing temperature during operation is therefore significantly lower. Bearings of the toroidal crowned design are available for a bore diameter of, or larger than, d = 90 mm ➤ dimension table.
Contact geometry of roller end face/rib face – modified roller end faces
Cylindrical roller with inner ring
Detail (representation not to scale)
End of roller
Rib
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Load ratio Fa/Fr
Ratio Fa/Fr ≦ 0,4 or 0,6
The bearings can support axial loads on one side by means of the ribs on the inner and outer ring ➤ Figure. In order to ensure problem-free running (tilting of the rollers is prevented), they must always be subjected to radial load at the same time as axial load. The ratio Fa/Fr must not exceed the value 0,4. For bearings with toroidal roller ends (TB design), values up to 0,6 are permissible.
Continuous axial loading without simultaneous radial loading is not permissible.
Permissible axial load
Influencing factors on the axial load carrying capacity
Axial loads are supported by the bearing ribs and the roller end faces ➤ Figure and ➤ Figure. The axial load carrying capacity of the bearing is therefore essentially dependent on:
- the size of the sliding surfaces between the ribs and the end faces of the rolling elements
- the sliding velocity at the ribs
- the lubrication of the contact surfaces
- tilting of the bearing
- friction
Force flow under axial load – semi‑locating bearing LSL1923
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Calculation of permissible axial load – cylindrical rollers with conventional roller ends
Bearings with standard roller ends
The permissible axial load Fa per can be calculated from the hydrodynamic load carrying capacity of the contact ➤ Equation.
Permissible axial load – bearings of standard design
Legend
Fa per |
N |
Permissible continuous axial load. In order to prevent unacceptably high temperatures in the bearing, Fa per must not be exceeded
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Fa max |
N |
Maximum continuous axial load in relation to rib fracture. In order to prevent unacceptably high pressures at the contact surfaces, Fa max must not be exceeded
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kS |
- |
Factor as a function of lubrication method ➤ Table. The factor takes into consideration the lubrication method used for the bearing. The better the lubrication and in particular the heat dissipation, the higher the permissible axial load
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kB |
- |
Factor as a function of the bearing series, kB = 28
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dM |
mm |
Mean bearing diameter dM = (D + d)/2 ➤ link
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n |
min-1 |
Operating speed
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Factor kS