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Double-sided deep groove thrust ball bearings consist of a shaft washer, two housing washers and a ball-cage assembly and can absorb high axial forces from both directions while radial loads are to be avoided. They are suitable for high speeds and can compensate angular errors and misalignments with a spherical shaft washer and an additional housing washer. Double-sided deep groove thrust ball bearings are not self-latching, so the ball-cage assembly and the bearing washers can be installed separately.

 

Dimensions and Tolerances

KRW supplies deep groove thrust ball bearings in accordance with DIN 620-3 (Tolerances for rolling bearings) and ISO 199 (Thrust bearings - Geometrical product specification (GPS) and tolerance values) in normal tolerance (PN). All other deviating or special tolerances must be specified with the order.

 

Rolling Bearing Tolerances

Standards

The general dimensions of double-sided deep groove thrust ball bearings are standardised in ISO 104 (Rolling bearings - Thrust bearings), DIN 616 (Rolling bearings - Dimension plans) and DIN 715 (Double direction thrust ball bearings).

 

Structure of a Deep Groove Thrust Ball Bearings double direction

Bearing Design

Double-sided deep groove thrust ball bearings are non-latching bearings that can be disassembled. They can absorb high axial forces from both directions while radial loads are to be avoided. To guarantee an accurate centring of the washers, the shaft washer is provided with a smaller sharpened bore. The bore of the housing washers is a little larger and is also rotated.

 

Bearing Clearance

The bearing clearance for single-sided deep groove thrust ball bearings is adjusted only after installation according to operating conditions. The temperature-dependent length variation of the operating components must be considered.

KRW cages

Cage

By default, KRW deep groove thrust ball bearings are equipped with a solid brass cage (suffix: M). Other cage designs are available on request or chosen for specific applications and labelled accordingly on the bearing.

 

General Cage Information

Compensation of Angular Misalignments

Deep groove thrust ball bearings with smooth housing washer are not suitable for compensation of misalignments. Misalignments cause harmful ball movement and produce additional stresses in the bearing which reduce its operating life.

 

Deep groove thrust ball bearings with two-piece housing washer with a spherical contact area are suitable for compensation of misalignments between shaft and housing due to shaft deflections, angular errors and housing deformation.

 

Speed

The kinematic limiting speed nG is a practical mechanical limit value and is based on the mechanical fatigue strength of the rolling bearing as a function of its installation situation and lubrication. The limit speed must not be exceeded even under optimum operating conditions without prior consultation with KRW.

The DIN ISO 15312 (Rolling bearings - Thermal speed rating) does not specify a thermal speed rating nth for these bearings.

Admissible Operating Temperatures

The admissible operating temperature of a bearing is limited by cage material, dimensional stability of the bearing components (ball race and rolling elements), as well as lubrication. By default, KRW bearings are stabilised up to 200°C (S1). KRW provides roller bearings for higher operating temperatures on request.

 

General Information to Cage Material

Dimensioning

For dynamically loaded bearings

The service life formula according to ISO 281 L10 = (C/P)p for dynamically loaded bearings requires an equivalent load (P) from constant direction and size. To calculate P, calculation factors and the ratio of axial and radial load are required.

Equivalent dynamic bearing load Pa

The equivalent dynamic bearing load can be determined using the following formula:

Paequivalent dynamic load[kN]
Fadynamic axial force[kN]

 

For statically loaded bearings

Dynamic dimensioning loses its validity for bearings rotating at very low speeds (n x dm ≤ 4000 mm/min). The static load safety factor S0 is calculated as follows:

S0static load safety factor[-]
C0basic static load rating (from bearing chart)[kN]
P0 equivalent static bearing load[kN]
nbearing speed[min-1]
dmmean bearing diameter [dm = (D+d)/2][mm]

 

Static load capacity

Famax. axial static load[kN]

 

Minimum Axial Load

A minimum load is required for the reliable operation of a rolling bearing. If the minimum load is not reached, slippage may occur. This produces surface damage which leads to premature bearing failure. Deep groove thrust ball bearings are protected against slippage exclusively through a minimum axial load. The calculation for the minimum axial load for deep groove thrust ball bearings is shown in the following formula:

Fa,minmin. axial load[kN]
nmaxmax. operating speed[min-1]
Abasic static load rating (from bearing chart)[-]

 

If the value falls below this value, please consult KRW Application Engineering.

 


 

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