What is radial load and axial load

Thrust bearings

Due to their specific construction areThrust bearings ideally suited for low speeds with low centrifugal forces and high rigidity.

In relation to the radial ball bearing, the pressure angle in an axial bearing is increased to 90 °, so that only axial loads occur. The difference with this bearing is that all rolling elements bear evenly.

There are two different versions of the axial bearing: one-way and double-acting axial bearings.

The classic design of the axial bearing is supplemented by special designs: axial angular contact ball bearings, swivel bearings or slewing rings. Often thrust bearings are also used in combination with radial bearings.

Axial forces require thrust bearings

If the forces to be absorbed by a roller bearing do not act radially, but in the direction of the axis or shaft, these are referred to as axial forces. In order to dissipate these forces, bearings are to be provided that have a fundamentally different structure. These prevent a shift in the axial direction. Standard radial bearings are primarily designed to take up radial forces, but they can also take up small / medium-sized axial forces. But sometimes the axial forces are too great to use this solution sensibly.

In contrast to radial deep groove ball bearings, the load in axial bearings is evenly distributed over all rolling elements. Due to the special design, axial bearings are particularly suitable for applications with low to medium speeds and where very high rigidity is required.

The areas of application can be divided into 2 cases:

  • Example helical gear transmission: Both radial and axial forces occur here. A combination of radial and axial bearings on one shaft is therefore always required. The same applies to machine tools and packaging machines.
  • Example crane: Above all, large forces occur in the axial direction, here due to the crane's own weight and the loads to be lifted. There is a completely different load case: Above all, the shaft or axle must be secured against displacement in the axial direction. For this reason, the rolling elements are stored or arranged differently here so that only pressure forces act on them.

Embodiments: Axial bearings are either in the form of a ring, outwardly similar to radial bearings, but with larger dimensions, or in the form of discs for larger loads. However, if rollers are required as rolling elements, the permissible speeds are very limited, as it is not just pure rolling friction that occurs here. Here too, however, the radial loads must by no means be neglected; a combination of radial and axial bearings on one shaft is mandatory.

Types of thrust bearings

  • Axial deep groove ball bearings: No load in the radial direction; suitable for higher speeds.
  • Axial cylindrical roller bearings: Very high load capacity in the axial direction, insensitive to shock; also not loadable in the radial direction. Unsuitable for high speeds.
  • Axial spherical roller bearings: Can absorb axial as well as radial forces, also suitable for higher speeds. Can compensate for misalignments. Very robust and widely used, even with very large dimensions.
  • Axial needle roller bearings: Very flat design, ideally suited for particularly rigid and shock-resistant bearings with high axial forces.

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