Rotary bearings, like ordinary bearings, have rolling bodies and raceways. However, compared with the ordinary rolling bearings, there are many differences. The main points are as follows:
1) The dimensions of slewing bearings are large, and their diameters are usually 0.4-10 meters, some of which are up to 40 meters.
2) Slewing bearings generally bear several kinds of loads, not only axial and radial forces, but also large overturning moments. Therefore, a set of slewing support often plays the role of several sets of common rolling bearings.
3) The rotational speed of rotary bearing is very low, usually less than 10 rpm. In addition, in most cases, the slewing bearing does not rotate continuously, but only rotates back and forth in a certain angle, which is equivalent to the so-called "swing bearing".
4) There are great differences between rotary bearing and rolling bearing in manufacturing process, material and heat treatment.
5) Usually, the revolving bearing (turntable bearing) is equipped with ring gear for rotary drive and sealing device for dust prevention.
6) Rotary bearings (turntable bearings) are large in size, unlike ordinary bearings, which are not sleeved on the mandrel and installed in the bearing box, but are fastened to the upper and lower supports by screw.