# Self-aligning roller bearings

## Description

Self-aligning roller bearings are designed for extremely high loads and stresses and composed of two rows with symmetric barrel rollers that are positioned without constraints in the concave outer raceway. Thanks to this design, it is possible to compensate for shaft deflections and misalignments. Self-aligning roller bearings are equipped with a maximum of rolling elements of large diameter and length. Matching the rolling element geometry with the raceway provides homogeneous stress distribution and high load-carrying capacity.

## Dimensions/standards

In self-aligning roller bearings, the main dimensions are standardized according to DIN 635-2 (Radial-self-aligning roller bearings), DIN 616 (Roller bearings – boundary dimensions) and ISO 15 (Radial bearings – boundary dimensions).

## Tolerances

SLF produces self-aligning roller bearings with standard tolerances (PN) according to DIN 620-2 (Roller bearing tolerances – tolerances for radial bearings) and ISO 492 (Radial bearings – dimensions and tolerances). These bearings can also be delivered in other tolerances upon request.

## Bearing design type

Self-aligning roller bearings are non-detachable, self-contained roller bearings. They are equipped with two rows of rolling elements with a joint spherical raceway in the outer ring and raceways inclined toward the bearing axis in the inner ring. Because they can be swiveled into angled positions, self-aligning roller bearings are not sensitive to misalignment of the shaft related to the housing or shaft deflections.SLF self-aligning roller bearings are in general made in E design, and, for this reason, are not marked with the letter “E”. Our product portfolio includes self-aligning roller bearings with cylindrical and tapered hole. The design of these bearings includes an oil ring groove and oil holes at the outer ring (designation suffix .W33).
We supply self-aligning roller bearings in the 230, 240, 231, 241, 222, 232, 213 and 223 series. The self-aligning roller bearings manufactured by SLF are by default in the design type …MB.W33.

Under normal operating conditions and assuming a circumferential inner ring, self-aligning roller bearings can be swiveled by 0,5° out of the central position to compensate for misalignment without any limitation. At low loads and stresses, swiveling angles up to 2° are permissible.

## Clearance

It is standard at SLF to deliver self-aligning roller bearings in the clearance class CN according to DIN 620-4 ( Roller bearing tolerances – radial clearance) and ISO 5753-1 (Roller bearings – clearance – radial clearance). We also deliver design types in other clearance classes or special clearance upon request.

Clearance table for self-aligning roller bearings:

## Cage

It is standard to supply self-aligning roller bearings with brass cages. We can also deliver other cage design types upon request.

## Working temperature

SLF-self-aligning roller bearings are standard stabilized in dimensions by S1, meaning that they are subjected to heat treatment that makes them usable up to 200°C. As a rule, however, the maximum working temperature is not limited by the dimensional stability of the bearing rings and rolling elements; frequently it is limited by the cage or lubricant / grease. Please find the necessary information in the relevant chapters. If you are uncertain or have specific questions regarding our bearings’ temperature limits, don’t hesitate to contact the SLF team.

## Greasing/lubrication & sealing

Upon request, self-aligning roller bearings made by SLF can also be delivered sealed on both sides. The sealed self-aligning roller bearings are filled with high-quality grease and should not be rinsed before installation. Sealed bearings of the 222 and 223 series are slightly wider due to the sealing.
In self-aligning roller bearings without seals, the bearing position must be sealed around/ on the surrounding components. We deliver unsealed bearings ungreased, but they must be filled with oil or grease before use. Choose the lubricant according to the application.

## Dimensioning


 $$P=F_r+Y_1*F_a$$ for $$\frac{F_a}{F_r} \leq{e}$$ $$P = 0,67 * F_r + Y_2 * F_a$$ for $$\frac{F_a}{F_r} > e$$

Values for e, Y1 and Y2 are provided in the product table (Online-catalogue)

To avoid slippage between elements in contact, the self-aligning roller bearings must be sufficiently loaded. A minimal radial load in the order of magnitude of

$$P > \frac{C_0}{100}$$

has been shown to be necessary.

In most cases, the radial load resulting from the weight of the components run on bearings combined with the external forces is higher alone than the minimal load required. Should this value not be met, contact an SLF application technician.


 $$P_0 = F_{0r} + Y_0 * F_{0a}$$
$$S_{0} = \frac{C_0}{P_0}$$