Power at Work: Machinery parts need a good, tight fit

What constitutes a good bearing fit on a shaft? Zero or negative clearance


In our mechanic’s world, thread locker chemicals have a close cousin called retaining compounds. These are similar to the thread lockers. The purpose of the retainer compound is to take up small amounts of space and keep things in place.

With many bearing-on-shaft installations, even a space as small as one-half of a thin piece of paper is too much space. As the shaft turns, the inner race of the bearing will wear away the shaft. So, think about the last time you changed such a bearing. Did you run your thumb nail along the shaft and feel that little groove where the old bearing has worn away the shaft?

Better Farming - March 2009