Slewing gear

from Wikipedia, the free encyclopedia
Slewing ring at a windmill

A slewing gear , also known as a slewing ring , is a connecting element in technology and mechanical engineering for the transmission of rotary movements with a simultaneous blocking of the remaining 5  degrees of freedom (3 translations, 2 rotations). This storage usually has to transmit very large axial forces and absorb tilting moments. Classic applications are the slewing gear on cranes or excavators, as well as the rotatable mounting of the front axle on the drawbar of a truck trailer .

Technical development

Roller turntables

Until the beginning of the 20th century, the development of ball bearings was limited to applications with lower forces for reasons of strength. In conveyor technology, especially with cranes and excavators, the problem arose that a large part of the machine had to be rotatably mounted on the chassis, but at the same time had to be tilt-proof. A circular rail track was used for this, on which wheels mounted in the superstructure rolled. To prevent the superstructure from tilting, the engineers placed a steel pin, the king pin, in the middle of the track . This type of storage was also used in mill construction.

Cylindrical roller lathes

Cylindrical roller slewing ring on a cable excavator . A claw roller can be seen on the turntable.

Due to the dimensions and the unevenly distributed load on the individual wheels, the cylinder roller slewing gear was developed in the first half of the 20th century. The wheels were replaced by smaller cylindrical rollers. These are not stored in the superstructure, but on a separate roller carrier on the kingpin. Thus, like a cylindrical roller bearing, they can roll between a track on the lower and upper structure. However, the kingpin was still necessary to absorb the tilting moments, and claws were also used.

These are rolling bearings that consist of two rings that are rotatably mounted against each other with the help of balls or rolling elements (rollers) .

Slewing rings

The next stage of development are the ball slewing rings that are common today. Balls run on obliquely arranged annular tracks like in an angular contact ball bearing and can thus absorb axial forces and tilting moments. The entire bearing is protected against grease leakage and dirt with seals. For special applications there is a large number of further developed designs, e.g. B. with several ball tracks.

Applications

Roller slewing ring on a turntable
Trailer drawbar with ball slewing ring (turntable trailer )

See also

Web links