Slewing rings are large-diameter roller bearings with high load capacity, which are designed for slow, rotary or oscillating movements (pivoting movements),

Slewing rings are ball or cylindrical roller bearings with a large diameter and usually consist of an inner ring and an outer ring, wherein one of the two rings is usually designed with a gearing. If the bearings are not as full complement bearings designed, the rolling elements are held by separators at a distance; not by means of a cage as usual for rolling bearings. The bearing rings are provided with holes for the mounting screws. Integrated seals protect the bearing system from harmful environmental influences and prevent the grease from escaping.

Photo of an IBO four point contact ball bearing with an outer gearing
IBO four point contact ball bearing with outer gearing - cross section
Photo of an IBO axial radial roller bearing - cross section
IBO axial radial roller bearing - cross section

Slewing rings can support axial and radial loads as well as moments loads and are installed in the majority of cases in a horizontal position. However, slewing rings can also be used in a vertical position. In general, slewing rings are installed on top. For suspended storage, the limit load curves are not applicable and an increased number of screws is required for attachment to the adjacent construction. The screws are tensile stressed by the axial load on.

The compact design and the freedom of the center allow the simplified arrangement of drive units and other controls. The arranged on the rotating ring units are more accessible. The low height of the bearings reduces the cantilever length of the drive pinion.

Slewing rings are used in a variety of applications as a reliable system solution:

  • General engineering
  • Antenna and radar equipment
  • Builders and cranes
  • Pivot mountings
  • Aerospace
  • Telecommunications technology
  • Offshore technology
  • Steel plants
  • Telescopes
  • Tunneling machines
  • Packing and filling machines
  • Water treatment
  • Tooling machines
  • Wind and solar energy systems

Slewing rings are special bearings or system solutions tailored to the application. For the reliable design of slewing rings, the correct dimensioning of the bearing raceways, the teeth and the screw connection is essential. For that, the most important information is:

  • Loads
  • Load collectives with associated time proportions in %
  • Position of the bearing axis (horizontal, vertical, reciprocal)
  • Design of the bearing (overhung, hanging)
  • Type of movement (setting, swiveling or rotary movements)
  • Speed or number of swivel movements and swivel angle per unit time with associated load collective
  • External forces, the are to be transferred by the gearing
  • Dimensions of the installation situation
  • Special environmental and operating conditions (e.g. running accuracies, temperatures, humidity, acceptance conditions, etc.)

Based on the data, we are happy to develop a technically suitable and economical system solution with corresponding technical calculations such as service life, bolt calculations, gear calculation and calculation of the friction torque.

The bearing rings of slewing rings have a very limited inherent rigidity due to their relatively large diameter in relation to the cross-sectional area. Thus, the bearing behavior of the bearing system is essentially determined by the supporting stiffness of the adjacent construction. Finite element calculations support optimal design. IBO has the necessary software solutions and know-how in the application and the data exchange allows a reduced effort in the prototype development.

About the known slewing rings with inductively hardened raceways, IBO supplies slewing rings with through hardened bearing rings as well as systems made of light materials. For more information about lightweight systems, see raceway systems.

Photo of an IBO four point contact ball bearing with an inner gearing
IBO four point contact ball bearing with an inner gearing

Manufacturing sizes

Up to an outer diameter of 4.500 mm


  • Four point contact ball bearings
  • Double-row ball slewing ring
  • Ball-roller slewing ring
  • Cross roller bearing
  • Axial radial roller bearing (triple-row roller slewing rings)

Bearing rings materials

Heat-treatable steel (standard), for special applications stainless steel also possible

Roller bearings materials

Roller bearing steel (Standard)

Ring heat treatments (hardness gap)

The bearing races are inductively or flame hardened as standard. The unhardened point between the beginning and the end of the hardening of the bearing raceway is marked with a punched-in “S“on the inner and the outer diameter (depending on the gearing).

Heat Treatments

Balls or rollers are hardened.

Cage materials

The segments or spacers are of synthetic material.


To connect with the transmission the design can have interior or exterior gearing.

The gear rim can be variously hardened according to the demands on it and thus the expected surface pressure. To increase wear resistance the teeth can also be hardened..

Please contact our Engineering in relation to gear calculation.

Dimensional and running accuracy

See the accompanying delivery drawings for dimensional and running accuracy. We can manufacture slewing rings to a precision of IT4.


The bearings are sealed and are delivered greased. The first re-lubrication of the raceway system and the gear teeth must be immediately after installation.

Please contact our Engineering in relation to the lubricants to be used and periods between lubrication..

Connection to adjacent construction

Bolt connection – fixing holes needed for this are provided in the bearing rings.

Please contact our Engineering in relation to bolt connections (calculation, configuration and application).