Light Slewing bearings are special types of bearings which are generally used in some machinery. The way they are mounted on the structures, working nature which is generally “static”, higher load carrying capacity, and larger number of rolling elements.
Light slewing bearings are generally selected on the basis of the static load, which is calculated using the forces for axial and radial loads coming on it as well as the tilting moment. For correct selection of the slew bearing, certain parameters such as speed, load, and operating temperature are required. There are certain assumptions which are to be considered:
1. The bearing is made from high quality material and is free from manufacturing defects.
2. Bearing is selected as per the load calculations.
3. Installation of the bearing is proper.
4. Grease used is of good quality and it reaches to every corner of the bearing.
5. Bearing is sealed using high quality seal.
6. Operating temperature of the bearing is within range.
7. Proper care for maintenance is ensured.
The conditions mentioned above, if fulfilled, ensure maximum bearing life.
When the slew bearing is rotating, the rolling elements are rolling in cyclic pattern over the inner raceways. Since the rotational speed is very low (mostly below one RPM), the phenomenon of gradual pitting and chipping takes place. Pitting is caused by the heavy loads on roller elements. The durability of the slew bearings who have undergone improper induction heat treatment are more prone to failure in early stages of the operating cycle. If this occurs, the bearing must be replaced or repaired immediately, as by not doing so, pitting will be more and that might result into jamming of rolling elements inside the bearing. This may also cause the ring to crack in extreme conditions, if it is not taken care of.The causes for such failures is mainly due to the excessive over loading of the bearing.
