In the portable belt conveyor conveying bulk materials, the belt center line from the belt machine center line, and the phenomenon of deviation to the side known as deviation. Due to the belt deviation may cause the belt edge and frame wear each other, so that the belt edge damage, shorten the service life. When the running deviation is serious, the belt will detach from the roller and fall off, causing a serious accident in the operation of the belt conveyor. Therefore, special attention should be paid to the running state of the belt during the installation, adjustment, operation and maintenance of the portable belt conveyor to prevent the belt from deviation and causing accidents. There are many factors that affect the deviation of portable belt conveyor, but the root cause is due to the inherent factors of uneven belt force. Firstly, the structure and workmanship of belt is decisive factor. For example, the belt core in the manufacturing if the force is uneven, may occur in the operation of off-tracking phenomenon. And such as  belt is not straight, that is, the joint and the center line of the belt is not vertical, resulting in uneven belt force, so that the belt deviation. In addition, the installation quality and adjustment of idlers and rollers also have a great impact on the deviation of belt conveyor. When installing the belt conveyor, it is required to be straight, so that each roller line and each roller axis should be perpendicular to the center line of the belt conveyor. Otherwise, the belt will be in operation by the transverse thrust and the phenomenon of deviation. Basic rules of deviation of portable belt conveyor:
(1)tight running without loose running: in the process of belt conveyor transportation, if the center line of front and rear rollers is not parallel, resulting in different tightness on both sides of the belt, the belt will move to the tight side;
(2) running high without running low: if the supporting roller is not in the same horizontal position parallel to the running direction of the rubber belt, but is high at one end and low at the other, the rubber belt will move to the high end:
(3) after running, not before running: the roller is not on the section perpendicular to the running direction of the rubber belt, but one end is in front and the other end is behind (according to the running direction of the rubber belt), then the rubber belt will move backward at one end. According to the analysis of the internal factors and the basic rules of the deviation of the portable belt conveyor, we get the following treatment methods for the deviation of the portable belt conveyor. The adjustment of belt machine deviation should be carried out in no-load operation. Generally, starting from the unloading drum of the head, adjust the return section first and then the bearing section along the running direction of the rubber belt. There are a variety of reasons for belt deviation, according to the different reasons for different treatment. According to the experience of our company's professionals in the use of portable belt conveyor, we have summarized some treatment methods for belt conveyor deviation, which are briefly introduced as follows:
1. Drum off-tracking method: the adjustment of driving drum and reversing drum is an important part of belt belt machine off-tracking adjustment. The installation position of all rollers must be perpendicular to the center line of the belt conveyor. If the deviation is too large will certainly occur deviation. The adjustment method is similar to the adjustment roller set.
2. Correction of drum off-tracking method: machining error on the outer surface of the drum, uneven wear or coal and other attachments on the outer surface of the drum, resulting in different diameters, the rubber belt will run off to the side with larger diameter. In this case, the solution is to replace the drum or clean up the surface of the drum sticky coal and other objects, to eliminate deviation.