The bearing rings used for slewing bearings have only a relatively large diameter in relation to their cross-sectional area. Consequently, their inherent stiffness is limited. For this reason, the supporting stiffness provided by the companion structures has a major influence on the load bearing characteristics of such a slewing bearing.

To be able to exploit the optimisation potential consistently, an integral calculation by aid of the finite elements analysis is imperative. Therefore, an optimum design is a joint task involving the slewing bearing manufacturer and the machine manufacturer.

The machine manufacturers calculate normally the adjoining companion structures by aid of finite elements models.

Defined interfaces can feed the information of the companion structures into the finite elements model of the slewing bearing enabling the calculation to consider the stiffnesses of the superstructure and of the undercarriage. Fully centralized development of an expensive overall model is no longer necessary.

This avoids the problems involved with having to interpret unfamiliar design documentation. A know how transfer does not take place.

The following part models are linked for the purpose of the analysis:

• the upper companion structure from the customer
• the slewing bearing including fastening bolts
• the lower companion structure from the customer.

The information of the part models can be easily exchanged by e-mail.



The special software is able to directly import the files with the stiffnesses of the companion structures as generated by the customer and to add them to the model of the bearing. Thus results a complete overall model with one calculation method which considers all major influence quantities simultaneously.

Schematic of the calculation method designed by Rothe Erde


Once the bearing calculation has been completed, the customer receives an e-mail with files containing data on the displacements and rotations of the interface nodes on the flanges of the companion structures. These data can be directly imported from his finite elements programme and used to calculate the corresponding internal stresses and deformations to which the companion structures are subject. This offers an economical means of optimising prototypes in which design weaknesses can be rapidly identified.

The developed calculation method offers the customer and the manufacturer an opportunity to participate in a long-term development partnership. The new method enables both, a highly economic and a thorough analysis from the mechanical point of view.

Experiments acknowledge that the use of this system allows a very precise calculation. This in turn greatly reduces the expenditure required for prototype development.