Slewing rings are large-diameter roller bearings with high load capacity for slow, rotary turning movements or slewing movements. In most cases, they are fitted to absorb axial forces and large tipping moments in horizontal positions. They have been installed for years particularly in excavators and cranes as an operationally safe bearing solution and more recently in tunnelling machines and wind power appliances.

The dimensioning of large diameter slewing rings depends predominantly on their static load capacity, due to the usual high load present when not operational of at slow turning or slewing movements. Slewing rings are special large diameter roller bearings. The abbreviations and dimensions are not standardised.

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).