Double row full complement cylindrical roller bearings

Double row full complement cylindrical roller bearings are suitable where:

• Bearing arrangements are subjected to particularly high radial loads ➤ section
• Not only particularly high radial forces but also axial loads from one or both directions must be supported by the bearing position (semi-locating or locating bearing function)➤ section
• Bearing arrangements must have very high rigidity
• Axial displacements of the shaft relative to the housing must be compensated without constraint in the bearing (in the case of bearings with a non-locating or semi-locating bearing function) ➤ section
• Very high radial loads occur at lower speeds, i. e., the bearings do not need to achieve speeds as high as those of cylindrical roller bearings with cage ➤ section and ➤ link
• Space-saving designs are required despite very high load
• The bearings should be separable for easier mounting (bearings with non-locating bearing function) ➤ section and ➤ section

Cylindrical roller bearing with cage/single row full complement bearing, double row full complement bearing, comparison of speed and load carrying capacity

Cr = basic dynamic load rating

nG = limiting speed

Design variants

The standard range of double row full complement cylindrical roller bearings comprises:

In addition to the bearings described here, Schaeffler supplies double row full complement cylindrical roller bearings in other types, series and dimensions. These products are described in some cases in special publications. If necessary, please contact Schaeffler. Larger catalogue bearings GL 1.

Bearings of basic design – standard range

Key features

Double row full complement cylindrical roller bearings are part of the group of radial roller bearings. These bearings comprise solid outer rings, inner rings and full complement rolling element sets. Due to the absence of a cage, the bearing can accommodate the largest possible number of rolling elements. 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. Bearings in the standard range differ essentially in the arrangement of the ribs on the inner ring and outer ring. Depending on the design, they are used as non-locating bearings, semi‑locating bearings or locating bearings.

Series SL0248, SL0249

Bearings with non-locating bearing function

In bearings of these series, the inner ring has three rigid ribs, while the outer ring is without ribs ➤ Figure.
As a result, axial displacements of the shaft relative to the housing can be compensated within certain limits. During rotational motion, length compensation occurs without constraint in the bearing between the rollers and the raceway without ribs and is therefore practically free from friction. The maximum axial displacement s is given in the product tables. The bearings are used as non-locating bearings, i. e. they cannot guide the shaft axially in either direction ➤ section. The series SL0248 and SL0249 are not self-retaining (the outer ring without ribs can be removed from the bearing). As a result, the bearing parts (the inner ring with the rolling element set and the outer ring) can be mounted separately from each other. This gives easier mounting of the bearings ➤ section.

According to DIN 5412-9:1982, which has now been withdrawn, the bearings have the following designation:

• SL0248: NNCL48..V
• SL0249: NNCL49..V

The bearings are held together in handling and mounting by a transport and mounting retaining device on the outer ring ➤ Figure. This retaining device remains in the bearing even after mounting and must not be subjected to axial load.

Double row full complement cylindrical roller bearing –
non‑locating bearing

Fr = radial load

Transport and mounting retaining device

Series SL1850

Bearings with semi-locating bearing function

Bearings of series SL1850 (dimension series 50) have three rigid ribs on the inner ring and one rigid rib on the outer ring ➤ Figure. In these cylindrical roller bearings, axial displacements of the shaft relative to the housing are possible in one direction only. The maximum axial displacement s is given in the product tables ➤ link. The bearings are used as semi-locating bearings, i. e. they can guide the shaft axially in one direction ➤ section.

The bearings are held together in handling and mounting by a transport and mounting retaining device on the outer ring ➤ Figure.
This retaining device remains in the bearing even after mounting and must not be subjected to axial load.

Double row full complement cylindrical roller bearing –
semi‑locating bearing

Fr = radial load

Fa = axial load

Transport and mounting retaining device

Series SL0148, SL0149

Bearings with locating bearing function

In these bearings, the inner ring has three rigid ribs and the outer ring has two rigid ribs ➤ Figure. Axial displacements between the shaft and housing are not possible. The bearings are used as locating bearings, i. e. they can guide the shaft axially in both directions ➤ section.

According to DIN 5412-9:1982, which has now been withdrawn, the bearings have the following designation:

• SL0148: NNC48..V
• SL0149: NNC49..V

The split outer ring is held together by a transport and mounting retaining device ➤ Figure. This retaining device remains in the bearing even after mounting and must not be subjected to axial load.

Double row full complement cylindrical roller bearing –
locating bearing

Fr = radial load

Fa = axial load

Retaining ring

Series SL0450..-PP and SL04..-PP – cylindrical roller bearings with annular slots

Bearings with locating bearing function, particularly suitable for the support of rope sheaves

These bearings comprise solid outer rings without ribs, inner rings with three ribs, rib-guided rolling element sets and sealing rings ➤ Figure. The outer rings have annular slots for retaining rings. The inner rings are axially split, 1 mm wider than the outer rings and held together by a sheet metal ring. They are used as locating bearings (but can support only slight axial loads) and are used in preference for the support of rope sheaves.

Light series and dimension series 50

Cylindrical roller bearings with annular slots are available as a light series SL04..-PP and in the dimension series 50 as SL0450..-PP. The latter has a higher load carrying capacity than the light series ➤ link.

Extensive information on rope sheave bearing arrangements is given in the Technical Product Information TPI 237. This publication can be requested from Schaeffler.

Double row full complement cylindrical roller bearing with annular slots –
locating bearing

Fr = radial load

Fa = axial load

Slots in outer ring

Sealing rings

Sheet metal ring

Retaining rings

Rope sheave

X-life premium quality

Double row full complement cylindrical roller bearings of series SL1850 are available in many sizes as X-life bearings ➤ link. 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, the better surface quality and the optimised roller guidance and lubricant film formation.

Advantages

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.

Areas of application

Due to their special technical features, double row full complement X-life cylindrical roller bearings are highly suitable, for example, for bearing arrangements in:

• heavy industry (steel production)
• power transmission (gearbox engineering)
• processing machines and construction machinery
• wind turbines (gearbox applications)

X-life indicates a high product performance density and thus a particularly significant benefit to the customer. Further information on X-life ➤ link.

Designed for very high radial loads

Depending on the type, double row full complement cylindrical roller bearings can support not only very high radial forces but also high axial loads on one or both sides:

• The series SL0248 and SL0249 must not be subjected to radial load
• The series SL1850 can support radial loads as well as axial loads on one side
• The series SL0148 and SL0149 can support radial loads as well as axial loads on both sides
• The series SL0450..-PP and SL04..50-PP can support radial loads and are suitable for the support of moderate axial loads from both directions

Higher axial load carrying capacity of bearings with toroidal crowned roller end face

Neither wear nor material 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 axial frictional torque is reduced by up to 50%. The bearing temperature during operation is therefore significantly lower. Bearings of toroidal crowned design ➤ link.

By agreement, bearings of series SL1850 are available starting from a bore diameter d = 180 mm in the TB design.

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

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. 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 SL1850

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

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

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

kB -

Factor as a function of bearing series ➤ Table

dM mm

Mean bearing diameter dM = (D + d)/2 ➤ link

n min-1

Operating speed