In previous articles, we discussed the cost drivers when it comes to transmission belts and the differences between the cores that are found in this kind of belting. Based on the title, you can see that there are three common covers that are found on transmission belts; leather, rubber, and tempered polyurethane (TPU). In this article, we are going to discuss the differences between these three coatings.
Let’s go over the basics, rubber and TPU are both synthetic materials whereas leather is made from tanning the skin of animals. The process of tanning can be done with or without chemicals and contributes a great amount to the strength and the abrasion resistance of the belt.
TPU is stronger than rubber whereas rubber is more elastic than TPU. This means several things. First, TPU is going to be more abrasion resistant than rubber. Also, since TPU is stronger, it can withstand more cycles of being stretched than the other two covers. This means that TPU generally lasts longer. Leather, however, can last longer in cases where there are high startup loads or when there are chances of the machine choking down. When a machine chokes down, leather will slip, rubber burns, and TPU can break the machine if it is too strong.
When it comes to noise, rubber absorbs more vibrations allowing to be quieter than TPU. Leather is the loudest due to the fact that you have to join strips together to make a belt. Each place where the belt is joined is called a lap. Laps tend to be noisy when running. In regards to extreme temperatures, you will want rubber when the temperature is very hot and you will want TPU when the temperature is very cold. Leather operates somewhere in the middle of these two extremes. Lastly, let’s talk about chemical resistance. TPU generally has the highest chemical resistance and rubber follows it. The chemical resistance of leather all depends on the tanning process. I have linked a chart from a boot company that shows chemical resistance when it comes to materials being discussed. Hopefully this, along with the other transmission belt articles, can help you make an educated decision on your next belt.