FEEDOPERATIONS Choosing the right bearing The correct type must be used for each application including proper mounting and lubrication by Fred Fairchild Rotating shafts are used in many types of equipment in feed mills. This can vary from a simple hand wheel shaft to open or close a gate, to high speed shafts turning pulleys or blades in a piece of equipment. No matter the purpose of the shaft, it has to be supported with some type of bearing. These bearings vary from a simple plain sleeve-type bearing to a precision ball or roller bearing. Bearings are subjected to two forces or a combination of these forces. The first force is radial based on the forces that act perpendicular to the shaft. Examples of these are forces needed to hold a shaft in place from forces pulling perpendicular to the shaft. Keeping the hand wheel shaft in a fixed location while it is used to move the slide in a gate is one example. Another is to support the headshaft and pulley on a bucket elevator or conveyor. The second force is thrust force created parallel to the shaft that tries to pull the shaft out of the bearing. This type of force is always present in bearings securing a vertical shaft. An example of a piece of equipment that has both forces is a screw conveyor. It requires bearings that support the radial loads of the screw flight, but also needs at least one bearing to hold back the thrust that the screw flighting creates while it moves the material along the length of the conveyor. This is done by using a combination radial and thrust bearing on one end of the screw conveyor. A radial bearing can simply be a hole bored in a block of All rotating shafts must be supported by some type of bearing. Photo by Sergiy Goruppa For more information, see Page 126. 100 November 2012 / World Grain / www.World-Grain.comhttp://www.flour-improver.de http://www.World-Grain.com