Belts are commonly used as a means for power transmission in electric motor drive trains. Belt drives enable power transmission between two or more shafts through the use of pulleys and a belt linking the pulleys. They are generally more cost-effective than other options such as chain or gear drives. They can also act as a torque limiting device from the perspective of exhibiting belt slip before transmitting unexpected torque through the drive train.
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As with any mechanical device, it is imperative to properly select, install, and maintain belts to maximize the life of the belt and prevent premature wear. There are many factors that affect the overall life of belt drives and subsequently the wear on the belts. The table below notes several common causes for belt wear and respective preventive actions.
Root Causes | Preventive Actions |
|---|
Belt Slip | - Follow the manufacturer’s recommended procedure for belt selection, installation, and operation (size, speed, load, tension, etc.) |
Improper Tensioning | - Use a calibrated tension gauge when installing new belts or inspecting used belts - Follow the manufacturer’s recommended tension specifications |
Environmental Conditions or Contamination | - When selecting a belt, refer to the manufacturer’s recommended specifications for items such as temperature, humidity, or UV exposure - Prevent contaminants such as dirt, grease, or oil from accumulating on the belt or pulleys with guards and regular cleaning |
Misalignment | - Use calibrated instruments such as a laser alignment tool or dial indicators to ensure pulleys are properly aligned - Simpler alignment methods such as using a straight edge or string may be utilized if the more precise tools are not available |
Overloading | - When selecting a belt, refer to the manufacturer’s recommended specifications for load and speed capabilities - Avoid shock loads where possible (ie, sudden start, stop, or load change) - Calculate the required load capabilities of the system before selecting a belt |
Belt slip is very common with belt drives, and its unique vibration signature can be readily detected. The image below demonstrates how belt slip would be captured by vibration monitoring with the frequency spectrum. More severe cases of belt slip may exhibit visual or audible indications as well as an increase in temperature due to excessive friction. However, less severe cases of belt slip may be imperceptible without the insight provided by vibration monitoring. Real-time vibration monitoring provides perpetual insight into the health status of belt-driven machines which will prevent excessive wear on the system.
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If the belts are not properly installed and maintained, the aggravated wear may also extend to the connected components such as the pulleys and bearings. For example, an over-tensioned belt will put excessive stress on the belt, cause increased friction, and lead to stretching or other damaging effects. Additionally, this will increase the load on the pulley bearings and other components in the drive train which may lead to premature wear or failure for these linked components.
It is recommended to address indications of belt wear as quickly as possible to prevent further expedited wear on the belt. Beyond the previously noted maintenance issues, there are also quality issues to consider with machines running ineffectively, production output issues with machines running inefficiently, and potential safety hazards from premature failure.
