Shifting the idler axis with respect to the path of the belt, commonly known as "knocking idlers," is effective where the entire belt runs to one side along some portion of the conveyor or radial stacker. Training the belt with the troughing idlers is accomplished in two ways. When combinations of these two occur, the one having the stronger influence will become evident in the belt performance. This is contrary to the old "rule of thumb" statement that a belt runs to the "high" side of the pulley. When pulleys are not level, the belt tends to run to the low side. Pulleys with their axes at other than 90° to the belt path will lead the belt in the direction of the edge of the belt which first contacts the misaligned pulley. They should be kept that way and not shifted as a means of training, with the exception that snub pulleys may have their axis shifted when other means of training have provided insufficient correction. Take-up pulleys are sometimes crowned to take care of any slight misalignment which occurs in the take-up carriage as it shifts position.Īll pulleys should be level with their axis at 90° to the intended path of the belt. The greatest advantage here is that the crown, to some degree, assists in centering the belt as it passes beneath the loading point, which is necessary for good loading. Tail pulleys may have such an unsupported span of belt approaching them and crowning may help except when they are at points of high belt tension. As this is not possible on the conveyor carrying side, head pulley crowning is relatively ineffective and is not worth the lateral mal-distribution of tension it produces in the belt. Crown is most effective when there is a long unsupported span of belting, (approximately four times belt width) approaching the pulley. Relatively little steering effect is obtained from the crown of conveyor pulleys. The usual cases when a pattern does not emerge are those of erratic running, which may be found on an unloaded belt that does not trough well or a loaded belt which is not receiving its load uniformly centered.įactors Affecting the Training of a Conveyor Belt Reels Pulleys and Snubs Combinations of these things sometimes produce cases that do not appear clear-cut as to cause, but if a sufficient number of belt revolutions are observed, the running pattern will become clear and the cause disclosed. These are the basic rules for diagnosis of belt running troubles. When the belt is loaded off-center, the center of gravity of the load tends to find the center of the troughing idlers, thus leading the belt off on its lightly loaded edge. If one or more portions of the belt run off at all points along the conveyor, the cause is more likely in the belt itself, in the splices or in the loading of the belt. When all portions of a belt run off through a part of the conveyor length, the cause is probably in the alignment or leveling of the radial stacker or conveyor structures, idlers or pulleys in that area. The book will tend to shift to the left or right depending upon which end of that dowel rod the moving book contacts first. Then lay a book across the dowel rod and gently push push/roll it in a line directly away from you. The basic rule which must be kept in mind when tracking a conveyor belt is simple, "THE BELT MOVES TOWARD THAT END OF THE ROLL/IDLER IT CONTACTS FIRST." You can demonstrate this for yourself by laying a small dowel rod or a round pencil on a flat surface in a skewed orientation. Training or tracking the belt on your radial stacker or conveyor system is a process of adjusting idlers, pulleys and loading conditions in a manner which will correct any tendency of the belt to run other than centrally.
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