Poly-V Belts Explained

While standard poly-V (PV) belts typically feature a polyester cord tensile member, elastic belts are unique in that they feature a polyamide cord, which gives the belt elastic properties. This stretch can be extremely useful in high volume applications requiring improved reliability with lower overall drive cost.

Elastic Belt Construction

PV Belt Construction

Rubber Construction: 1. Belt Body, 2. Adhesion Cushion, 3. Tension Members, 4. Belt Back

Elastic belts are constructed in largely the same way as any other standard PV belt, differentiated mainly by their cord material: elastic nylon (polyamide). However,  the difference in cord material is not visible to the naked eye, but sometimes branding is included on the belt itself to indicate the material of construction.

Made of rubber or urethane, these belts allow for a certain amount of stretch but, PV elastic belts don’t stretch as a rubber band does; their elongation capability is generally less than 4%.

Elastic Belt Structure

Featuring an elastic nylon cord, these belts are each engineered for a specific drive according to the power characteristics of the machine. Commonly provided in rubber H and J pitches, as well as polyurethane H, J, and TB2 pitches, the belts feature high flexibility and offer the benefit of a smaller wrap angle on the drive pulley.

Elastic Belt Benefits

elastic pv belt elongationSince elastic PV belts can be stretched onto a drive and automatically adjust to correct tension upon installation, they offer a wide range of benefits for various applications.

Firstly, these belts are specifically designed for operation on a fixed center distance application, eliminating the need for tension idlers and slide adjustment.

The drive’s fixed center distance also allows for easy automation and robotic installation. For driver pulleys, a smaller wrap angle can be used.

Elastic belts act as damping springs, they’re capable of absorbing temporary overloads with minimal noise and vibration ensuring quiet, smooth operation.

Because these belts don’t require tensioning devices, fewer quality issues arise due to incorrect belt tension. This helps cut down on labor, as workers aren’t required to have the skills necessary to apply correct tension during the assembly process; the need for manual installation labor can be eliminated through the use of robotic installation methods. All of these features allow for lower overall costs.

Elastic Belts – Advantages

  • Elimination of the need for tensioning devices
  • Easy installation
  • Cost reduction through lower “overall” drive cost
  • Smooth, quiet operation
  • Absorption of overloads and intermittent loads
  • Reduced maintenance and labor needs
  • Mounting installation without requiring pulley removal
  • Are used with standard pulleys
  • Eliminates tension errors in the installation process

Elastic Belts – Disadvantages

Although poly-V elastic belts offer a wide range of benefits, they’re not without their drawbacks.

  • Not intended for high-power applications (> 2-3 kW)
  • Can only be used on the drive for which it is designed
  • Non-Stock – made to order

Common Applications

Poly-V elastic belts are often used in the following applications:

  • Washing machines and dryers
  • Small appliances such as food processors (In these applications, polyurethane is ideal for optimal cleanliness)
  • Exercise equipment
  • Any application necessitating elimination of idlers

Learn More

Megadyne America offers elastic multi-V belts in both rubber and polyurethane, with several pitches available to suit your specific needs.  Want to learn more about our PV belting capabilities or discuss your next belting project? Contact us today to speak with one of our experts.

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