Based on the exposure in the previous article, we know the importance of preloading. There are many methodologies available for the preloading of the bearings in which Spring Preloading of bearings is one of them.
Spring preloading is one of the simplest procedures for preloading a bearing and always has a first preference. Though the current design methodologies adapt to various other modes of preloading, spring preloading always has significance. The main advantages of spring preloading are as follows
· It tends to provide a constant preload from the spring and is very less sensitive to differential expansion and expansion of the bearings due to thermal variations
· They tend to act as an automatic mechanism, which account for the wear in the bearings. As the bearing wears out, the spring is always ready to expand to account for the wear and preload the bearing again.
· It has the capability to accommodate minor misalignments occurring during the preloading and moreover supports the bearing to the full.
Just like the advantages they also tend to have their own disadvantages. Some of the disadvantages of this method are
· As time passes, the springs tend to loose their stiffness and hence may not be able to provide the preload to the maximum possible.
The various types of springs that are used for preloading of bearings are as follows
· Coil Springs
· Belleville Springs
· Wave springs and
· Finger Springs
The basic principle of the arrangement is such that the spring is compressed during assembly by the outer race of the bearing. The main reason why the outer race is preloaded is that the outer race is normally the non-rotating member. If the outer race is not directly made to compress the spring, other methodologies are followed to compress the bearing. Care is also ensured that the spring does not buckle due to the compression and ample supports are provided for the spring.
We will look in detail on the other preloading methods in the forthcoming articles.