Question

Scenario 2: After installing a multiple belt system, you noticed the same belt keeps breaking. Answer the following: 1. What may be (2) reasons as to why the belt keeps breaking? (x2) 2. Are there tools to use in testing why the same belt keeps breaking, or to determine what type of belt it is? If so, name it/them and how do you use it them? (x2) 3. True or False.If a belt beaks in a multi-belt system, replacing only the broken belt is ok because it helps save money? BONUS Question (Bonus Points): How will replacing only the broken belt save money or how will it not save me money in the long run? (Answer is dependent on how you answered Scenario 2 Question 3)

Answer 1

A multiple belt system consists of more than single belts installed together. It is very important that in the multiple belt system, the tension should be distribued on all the belts in uniform manner. If the tension is different in different belts then the elongation of each belt is different. The belt system therefore is not able to stay in equillibrium due to the different elongation in different belts.

1. In this situation, we find the same belt is breaking down which is possibly due to

A1. The stress created due to elongation of the belt. The belt is improperly fitted or has different material properties than rest of the belt system. This creates pulling of the belt due to different belt velocity. The resulting stress tears off the belt due to unability of the belt to handle extra load due to its material properties such as load carrying capacity.

A2. Another possible reason is due to vibrations in the system the belt is wearing out faster than other belts. The system needs to be realigned properly to adjust the tension in all the belts so as to maintain the velocity of the belt system in balance.

B. It is definitely possible to find out why the same belt keeps breaking or to determine type of belt. The tension inside the belt is due to the velocity of the system. The spring tension meter or tension tester is a device which uses frequency waves to detect the tension in the belt. This tool can be used while the belt is running to record the elongation and stress the belt is undergoing.

       Another method of checking belt wear is visual inspection with eyes. The top portion, bottom portion, belt edges, sheaves etc needs to be carefully observed to locate any abnormality such as wear and tear, cracking on the belt, broken rubber material, abrasion of belt, uneven wear on ribs, oil contamination etc. This analysis could lead to possible exact root cause of the failure.

B.2 The type of belt is easy to understand with bare eyes. The belts are identified as per the shape of the belt cross section. The round belts, V shaped belts, Flat belts and toothed belts are easy to distinguish from each other simply by looking at the material geometry.

C. False. If one belt breaks in multi belt system then it is required to change all belts at the same time. Due to different wear of the belts the tension created is not uniform in the system. As noted above the tension in all the belts should be equally distribued in the system. When one of the set of belts break, the entire set should be replaced at the same time. If only one belt is replaced, theold weared out belts wil be loose and can not match the speed of new belt which is tight.

Bonus - If only one belt is replaced then the system is going to break down in short run. The cost for replacing this entire system frequently is more due to wasted human power, time to repair, machine productivity reduction and performance degradation. The cost is saved by replacing entire belt system at once becasue it lasts longer and gives standard performance.