# Thrust ball bearings

## Description

Due to their design, thrust ball bearings are detachable, and the bearing components can be assembled separately. These bearings are formed as single and double row types. Thrust ball bearings are only suitable for axial loads, while radial loads must be avoided. Due to their kinematic characteristics, thrust ball bearings should be used for low to medium speed ranges.

## Dimensions/standards

In thrust ball bearings, the main dimensions are standardized according to ISO 104 (Roller bearings – thrust bearings), DIN 616 (Roller bearings – boundary dimensions) and DIN 711 (Thrust ball bearings, single direction), as well as DIN 715 (thrust ball bearings, double direction).

## Tolerances

As the default, we produce SLF-thrust ball bearings with standard tolerances (PN) according to DIN 620-3 (Roller bearing tolerances – tolerances for thrust bearings) and ISO 199 (Thrust bearings –Geometric product specification and tolerances). We deliver bearings in other tolerance classes or special tolerances upon request.

## Bearing design types

### Single direction thrust ball bearings

Single direction thrust ball bearings consist of a shaft washer, a seating washer, and the ball complement inside a cage. Bearings of this type can withstand axial forces in only one direction. The SLF standard portfolio comprises bearings in the 511 and 512 series. We deliver bearings in the 513 and 514 series, as well as the 532, 533 and 534 series with spherical seating washers, upon request.

### Double direction thrust ball bearings

Double direction thrust ball bearings consist of a shaft washer, two seating washers, and two ball complements. These bearings can withstand axial forces from two directions and guide the shaft to both sides. We deliver double direction thrust ball bearings (522, 523, 524, 542, 543 and 544 series) upon request.

## Cage

The standard manufacturing of SLF thrust ball bearings uses steel plate cages. The exception is large-sized thrust ball bearings, which are equipped with brass solid cages (designation suffix: MP).

## Working temperature

SLF thrust ball bearings with a maximum 240 mm outer diameter are standard stabilized in size by S0, meaning that they are subjected to heat treatment to make them usable up to a working temperature of 150 °C. At more than 240 mm outer diameter, the thrust ball bearings are standard stabilized in dimensions by S1, meaning that they are subjected to heat treatment to make them usable up to a working temperature of 200 °C. However, as a rule, the maximum working temperature is not limited by the bearing rings’ and balls’ dimensional stability. Frequently the limitation is the cage or lubricant. For the necessary detailed information, see the corresponding chapters. If you are uncertain of have specific questions regarding the maximal temperatures our bearings withstand, don’t hesitate to contact the SLF team.

## Greasing/lubrication & sealing

Thrust ball bearings are manufactured without seals. Consequently, the bearing location has to be sealed around/ on the surrounding components. The sealing must ensure that no moisture and/ or contaminants can enter the bearing and that no lubricant is lost.
Thrust ball bearings are delivered ungreased, but must be lubricated with oil or grease. Choose the lubricant according to the application.

## Dimensioning

### Dynamic equivalent load

$$P = F_a$$
 P dynamic equivalent load [kN] Fa axial dynamic load [kN]

### Static equivalent load

$$P_0 = F_{0a}$$
 P0 Static equivalent load [kN] F0a axial static load [kN]

### Static load safety factor

In case of statically loaded thrust ball bearings, always check static load safety factor S0 in addition to nominal lifetime L (L10h).

$$S_0 = \frac{C_0}{P_0}$$
 S0 static load safety factor [-] C0 static load rating [kN] P0 static equivalent load [kN]

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### Required minimal load

If thrust ball bearings are run at high speeds with low loads, centrifugal force presses the balls to the outside. As a result of centrifugal forces and gyratory moments, the rolling elements slide against the tracks, which is harmful. To avoid these sliding effects, the bearings must always be run at or above the axial minimum load Famin.
For SLF thrust ball bearings, the minimal axial load should be 4% of the dynamic load rating. If you intend to use the bearing below this value, please contact an SLF application technician.

### Reference speed (calculation basis):

The reference speed is calculated according to ISO 15312 and is the speed at which, under defined reference conditions, a bearing operating temperature of +70 °C is achieved. It is not a speed limit for the application of a bearing but provides the basis to compare the speed suitability of different bearing types.