March 19, 2006

By: Mark Harris
Website: http://www.bearing-n-bearings.com

Bearing preload.An explanation of a vital but largely misunderstood area of bearing technology from Trevor Morris of The Barden Corporation

Preloading and axial adjustment is the operation of controlling the internal clearance of a bearing. This is important because the degree of internal clearance within a bearing can influence noise, vibration, heat build-up, and also fatigue life. When applied correctly, pre-loading reduces or overcomes the causes of these problems; it controls radial and axial play, and gives predictable system rigidity, reduces non-repetitive run-out, reduces the difference in contact angles between the inner and outer rings at very high speeds and controls ball skidding under very high acceleration.

Preloading and Axial Adjustment Techniques

In all bearing arrangements where preload is judged to be necessary, it should be applied as lightly as possible to achieve the desired result, avoiding excessive heat generation, which reduces speed capability and bearing life. In addition, it is important to choose the most appropriate method of preloading, there being three main types: Springs, Axial Adjustment and Pre-load Ground Duplex Bearings. Of the three, springs are usually regarded as the simplest method and should be considered first. Spring preloading provides a relatively constant preload because it is less sensitive to differential thermal expansion than rigid preloading, and accommodates minor misalignment better. Also, it is possible to use bearings, which have not had the added cost of preload grinding. A disadvantage is that spring preloading cannot generally accept reversing thrust loads. Space must also be provided to accommodate both the springs and spring travel, and springs may tend to misalign the ring being loaded due to required clearance fits.

About The Author:

Mark Harris is a successful author and regular contributor to http://www.bearing-n-bearings.com.  Keep things running smoothly with ball bearings, roller bearings, ball thrust bearings and tapered bearings.