Top 8 Causes of V-Belt Failure


and how to prevent them...

V-Belts are a low maintenance solution that are suitable for mid to hugh power belt drives. This makes v-belts amongst the most common components in modern machinery, found in almost every industry. 

We have caught up with J3 Belts & Bearings Belt specialist, Jack McGilligan about what exactly causes premature v-belt failure and how we can help our customers get the most out of their v-belts. 


Although sidewall wear us inevitable over time, rapid sidewall wear can be a sign of a bigger problem as most commonly it can be attributed to worn or damaged pulleys. However, there are many other possible influencing factors such as: using belts in extreme heat, excessive oil, grease, moisture and other generally abrasive environments.

Solution: Ensuring pulleys are replaced when changing belts is critical to be certain that you are getting the most from your belt system. If the pulley wall is bright and shiny, it is time to replace it. 


Most commonly, back wear is a direct cause of the belt being forced or pried on to the pulley or that there is some misplaced slack within the belt. Although, on some occasions defective or worn backside idlers can contribute to worn backside covers, however, this is less common. 

Solution: Ensuring your belts have the correct tension on installation is essential. Even belts that are measured correctly need to be re-tensioned within 24-48 hours of installation.


Excessive exposure to oil or grease can be a recipe for disaster for some v-belts as these products can result in the belt softening and become swollen, and thus no longer fitting properly into the pulley groove.

Solution: A simple belt guard can prevent foreign bodies including oil & grease from contaminating the drive, while its always worth noting that belt dressings are to be avoided. If oil and grease is still a problem, consider using composite v-belt as these belts are usually unaffected by oil, grease, water and common industrial solvents.


Spin burn can be a cause by worn or damaged pulleys, and incorrect tensioning, which can wreak havoc on your belts causing damage and ultimately premature failure. This can also be less commonly caused by using the wrong belt cross section or type, excessive oil, excessive grease or moisture and insufficient wrap on a small pulley.

Solution: This type of wear means it's time to check your pulleys and belt tension as under tensioned belts and smooth pulleys mean unnecessary wear. 


There's a lot to be said about the damage that can be caused by forcing a belt onto a pulley or running your v-belts with the incorrect tension, as this is the most common cause for many types of belt damage, including cover splits.

Solution: If you're sure that there are no foreign objects in the grooves that could be causing the issue, then ensuring regular belt tensioning and the correct size belts are ordered every time can result in solving this issue.


Cracking in belts can result in serious issues, especially if they are left untreated as they can affect drive efficiency and eventually cause belt failure. Cracks commonly begin to appear on belts that are being exposed to excessive heat. Although it can be caused by pulleys and backside idlers that are too small or misaligned.

Solution: If your v-belts are working in extreme temperatures, it may be time to consider an EPDM Rubber belt that is designed to be able to withstand these temperatures.


Missing cogs can cause belts to slip and fail, when it is discovered there are teeth missing, the belt should be changed immediately. The most common reasons your belt could be missing a cog are:

  • excessive heat
  • Pulleys are to small
  • Pulleys are misaligned
  • Improper or prolonged storage of belts

Solution: If your cogged v-belts are working in extreme temperatures, it may be ideal to consider belts designed for these environments. Additionally, establishing that your pulleys are correctly aligned using a laser alignment tool can eliminate the possible cause and improve machine running. 


Having cracked bushings means your drive is in dangerous territory, if the damage becomes too severe,, your pulleys may not be attached securely to the shaft. Bushings can become cracked due to excessive tension from the drive or using worn out or damaged pulleys.

Solution: Over-tensioning belts can be just as damaging to your v-belts as under tensioning, using a belt tension gauge to check belt tension can help you avoid unnecessary bushing damage. 


V-Belt drives really don't need a lot of attention to be efficient but getting the basics right can avoid these types of failure and really improve the life span of your belts and pulleys.

  • Don't replace brand new belts on to worn pulleys as it can reduce the life of a belt by up to 50%.
  • If the pulley is only worn on one side, alignment may be the fault.
  • Laser alignment tools are by far the best way to check alignment and can increase the belt life.
  • Although some belts  are now manufactured and pre-tensioned, most v-belts need to be tensioned on installation and re-tensioned with 24-48 hours. Over tension and under tension can contribute to belt failure.
  • Never mix old and new belts on the same drive.
  • A simple guard can prevent foreign bodies contaminating the drive, if your drive is in a dusty environment and there is oil and grease present, this can create a paste that eats away at the most robust components.
  • Other environmental factors such as extreme temperatures, high or a very low ambient temperature, try using EPDM rubber belt. 


Get in touch with J3 Belts & Bearings' belt expert, Jack McGilligan today:

T: 028 7964 5581