V-Belts and Low Temperature Operation

In extremely low temperature operations, the rubber material in V-belts becomes stiff. At sufficiently low temperatures, the rubber will actually reach a glass point, where (as the name implies) the rubber is hard and will shatter like glass if it is bent.

This is an extreme condition but approaching this state the rubber will go through various degrees of stiffness. As long as a drive is in operation, the heat generated through drive friction and bending will increase the internal belt temperature and maintain belt flexibility in temperatures well below the normally accepted minimum operating temperature. Trying to immediately transmit a load through a belt which has taken a cold set can cause belt failure because the belt is too rigid to bend.

Minimizing Heat in V-belt Drives

The air temperature surrounding a belt drive is the ambient temperature. Operating temperature is the actual temperature of running belts. The operating temperature of belts always exceeds the ambient temperature.

Higher than recommended ambient and operating temperatures deteriorate rubber compound properties, leading to premature belt failures. However, there are ways to minimize the impact.

For high ambient temperature applications, increasing ventilation around the belt drive can help reduce belt operating temperatures. This can be accomplished by adding vents to belt guards, by adding fins to sheaves, or by providing a cooler external air source.

Belt slippage will increase operating temperature. If belt slippage is due to under-design, a re-design may be necessary to increase the capacity. If belt slippage is occurring on a properly designed drive system, the belt installation tension level may need to be increased or worn sheaves replaced.

If the heat source is within the belt drive system itself, re-designing may help. Some belt drive design tips to minimize heat generation are listed below.

• Select belt types with a higher ambient temperature range
• Use more belts to decrease the load per belt
• Use larger sheave diameters to reduce belt bending stresses
• Change to a smaller belt cross-section or use notched belts for increased flexibility

Temperature Effect on Belt Storage

To ensure belts maintain full performance capability, six years is the maximum recommended storage time.

To achieve full storage life, belts should be stored at temperatures below 85°F.  For every 15°F increase above 85°F, the recommended storage time is reduced by half.  It is not recommended to store belts at temperatures above 115°F.

For additional storage recommendations, refer to the Belt Drive Preventive Maintenance & Safety Manual: BeltPMManual.pdf

Gates Molded Notch V-belts Can Handle the Heat

Ethylene rubber is a robust material with excellent temperature and ozone resistance.  Several years ago, Gates developed and patented the technology to make ethylene rubber suitable for use in molded notch V-belts.

Gates latest molded notch single V-belt construction utilizes that patented technology to provide an allowable temperature range of -70°F to +250°F (vs. the industry standard of ‐30°F to +140°F).  The increased temperature range results in increased belt performance in high and low temperature environments. For more information on Gates molded notch V-belts, contact us at ptpasupport@gates.com or 303-744-5800.