Thrust Ball Bearings are separable axial bearings that are produced in both single and double direction acting design.
To assist in simple effective mounting or dismounting the bearing washers, seatings, and cage and ball assemblies, may be individually mounted in their arrangement location.
Thrust ball bearings may accommodate comparatively high axial loads but they must not be exposed to any radial forces.
Due to their specific kinematic behaviour, thrust ball bearings are only suitable for low to medium operating speeds.
Furthermore, they require minimum axial loads for their optimum function.
Since thrust ball bearings do not compensate any misalignment, they are also frequently used in conjunction with sphered housing washers or with both sphered housing washers and seating washers.
Thrust ball bearings are produced in both, single direction and double direction design. The most important design variants are shown on the below.
Single direction thrust ball bearings consist of a shaft washer, a housing washer and a ball and cage thrust assembly, (see a, b and c below).
These bearings are able to accommodate axial loads in one direction only.
Single direction thrust ball bearings of series 511, 512, 513 and 514 have plain housing washers, (see a below)
For applications where some misalignment may occur, single direction thrust ball bearings of the series 532, 533 and 534 are also available with sphered housing washers, figure b.
These bearings may be applied either direct to sphered shaped bearing seats or, they may be used together with seating washers of series U2, U3 or U4 (see c below).
All thrust ball bearing types with flat housing washers do not allow any misalignment.
The contacting surfaces of both shaft and housing seats must be parallel.
Misalignments can only be accommodated by using Thrust Ball bearings with sphered housing washers.
NKE thrust ball bearings are normally fitted with pressed steel cages as standard.
For larger thrust ball bearings solid brass cages, (suffix M), or solid steel cages, (suffix F), are fitted as standard.
NKE thrust ball bearings are produced to normal tolerance class (PN) as standard.
For applications of higher dimensional and geometrical accuracy these bearings are produced to precision tolerance class (e.g. P6) on order request.
Standard plans DIN 616
Single direction DIN 711
Thrust ball bearings, double direction
Seating washers DIN 715 DIN 711
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Spherical Roller Thrust Bearings are separable single direction acting axial bearings (see sketch below).
NKE Spherical Thrust bearings are manufacttured to the standard boundary dimensions DIN 728 General.
Spherical roller thrust bearings are self-aligning as their spherical rollers run on the sphered raceways of shaft and housing washers. Therefore they are well able to accommodate errors of misalignment and some shaft bending in an optimum way.
Spherical roller thrust bearings transmit forces via a contact angle towards the centre axis. Thus, they are able to accommodate some radial forces along with high axial loads.
But, it must be considered that the acting radial forces must not exceed approximately 55 % of the applied axial forces.
NKE spherical roller thrust bearings are produced to normal tolerance class (PN) as standard.
Detailed tolerance values available on request
Spherical Roller Thrust Bearings are optimum to compensate for misalignments.
The permissible amount of misalignment from the centre position however, is dependant on both the bearing series and the applied loading.
Under normal operating conditions, such as a rotating shaft washer and permanent misalignment the, following values may be assumed:
Small and medium size NKE spherical roller thrust bearings are available with either solid brass cages (suffix M) or pressed steel cages (suffix J).
Large spherical roller thrust bearings are produced with solid brass cages (suffix M) as standard.
All Spherical roller thrust bearings require a certain minimum axial load to perform effectively.
To prevent excessive sliding friction, the minimum axial load applied should be over 5 %
of the axial bearing dynamic load rating Ca.
Where such a minimum load is not achieved, the load must be increased by effective measures, (i.e. preloading the bearing), using spring washers or springs etc.
Oil lubrication is preferred for spherical roller thrust bearings.
Grease lubrication is adequate only for applications where low loads and low speeds occur.
Particular attention must be made to ensure a sufficient grease supply to the contacting areas between the roller ends and guide flange. Frequent re - lubrication is necessary.
It must be considered that the recommended speed limits for grease lubricated spherical roller thrust bearings applies only to horizontal bearing arrangements. In the case of vertical arranged spherical roller thrust bearings, these values must be reduced by 50 %.
Abutment and fillet dimensions
In the case of spherical roller thrust bearings, an effective support of both bearing washers is necessary.The bearing washer must contact adjacent parts with their face sides only.
The fillet radii of bearing corners must not touch the shoulder fillet radii of the shaft or the housing shoulders.
Therefore, the largest fillet radius must be smaller than the minimum fillet dimension of the bearing rings.
To avoid any contact between rollers and the housing with high misalignments, the housing bore must be designed according to the recommendations. Further information can be made available on request.