How to prevent problems with belt flatness

1. Different types of parallelism

The first type is non parallel between one axis and the other (but both axes are horizontal), the second type is non parallel due to the offset of the pulley installed on the axis, and the third type is non parallel between two axes, and one or both axes are not parallel to the horizontal plane.

2. Causing consequences

a. The unevenness caused by the offset of the pulley can lead to a decrease in the performance of the Synchronous Belt, as it can generate a significant deviation force, resulting in uneven load on the teeth, wear on the bottom of the teeth, wear on the side of the belt, noise, and failure of the wire rope, all of which may be caused by uneven load on the wire rope. Of course, a wide belt will appear more severe in this situation.

b. The deviation of the pulley leads to non parallelism, which accelerates the wear of the belt and pulley, reduces the lifespan of a single belt, and leads to uneven load on the belt and rope, but it is not as obvious as in Figure 1. However, among the problems caused by the non parallelism of the two axes, the triangular belt is more severe than the synchronous belt. Triangle belts do not move freely on the pulley like Synchronous Belts (corrected by deviation), so their consequences are more serious.

Due to the non parallelism caused by the installation of two pulleys, if it is a synchronous belt, as long as there is no friction with the blocking edge or deviation on the pulleys during operation, there is no significant risk. The width of the synchronous belt pulley is designed to be larger than the width of the belt, mainly considering this factor and tolerance accumulation, allowing for a certain deviation of the synchronous belt during installation. As long as the width outside the engagement between the pulley and the belt exceeds the width of the belt deviation, the belt will automatically correct it on the pulley without friction with the pulley edge. But if the belt and pulley only make slight contact, we believe there is no problem.

c. In general, we can use a ruler or thin rope to measure parallelism, and sometimes incorrect use of measuring tools, especially thin ropes, can lead to incorrect conclusions.

You can use one side of the ruler to tightly adhere to the edge of one of the pulleys. If you use a thin rope, the principle is the same. Then, judge the parallelism by looking at the distance between the ruler or thin rope and the edge of the other pulley. When preparing to measure the parallelism of the pulleys, ensure that the thickness of the ribs between the two pulleys is consistent. It is more appropriate to measure the triangular or synchronous pulleys face to face according to the center, rather than using the outermost as a reference to confirm. When installing the pulley, sometimes a certain amount of deviation is given in advance to ensure that the main and passive wheels meet the parallelism requirements, so that the belt can run better on the pulley. The edge of the pulley also needs to ensure that there are no problems, because if the edge of the pulley is curved, the results obtained when measuring parallelism along its edge with a ruler or thin rope will be inaccurate. We must know what level of parallelism is acceptable and what level is unacceptable. So parallelism must be quantified and measurable. Usually, belt manufacturers have specified requirements for various belt parallelism under different driving conditions.