V-BELTS AND MAINTENANCE Most of today’s belt drives use standard V-belts, which have a trapezoidal cross section creating a wedging action on the pulleys. V-belts depend on friction as they are part of a wedging mechanical system. V-belt drives can run as high as 95-98 percent efficient at the time of installation. They are manufactured in a wide variety of materials, cross sections, banded multiples, reinforcement styles, and constant and variable speed configurations. Low acquisition costs, wide availability, and quiet performance make them a popular power transmission solution. A key difference between V-belts and synchronous, in terms of maintenance is that synchronous belts do not require a run-in procedure or retensioning. It is recommended that a newly installed V-belt is retensioned 24 hours after installation. V-belt drives and synchronous belt drives demand approximately the same amount of time for installation. “In most commercial applications the V-belt drive is the critical link and the only mechanism for mechanical transfer of power from the electric motor to the driven shaft/fan/blower,” said Don R. Sullivan, sr. product manager Belt Drives/Power Transmission Solutions for Emerson Industrial Automation. “Without high quality drive products, correct design, installation and maintenance procedures, a building owner is exposed to greater risk of unplanned downtime. By implementing a V-belt drive preventive maintenance program with sound fundamentals, (such as using premium V-belts, checking sheave wear, tensioning belts, and verifying alignment), building owners can ensure reliable drive performance and avoid inconvenient and costly repairs.” Sullivan said that in the past few years there has been a trend by users to specify notched/cogged style V-belts vs. traditional wrapped style V-belts. He noted, “The U.S. Department of Energy publishes that notched/cogged V-belts have slots that run perpendicular to the belt’s length. The slots reduce the bending resistance of the belt. Independent tests results show notched V-belts are 2-3 percent more efficient than standard wrapped style V-belts. “To put this in perspective, switching from a wrapped V-belt to notched V-belt on a single continuously operating 10hp drive operating at 75 percent load, and an electricity rate of 012.8 kWh results in annual savings of $255.26 (assuming a 3 percent efficiency gain). A facility with 20 rooftop units could save about $5,105.20 per year and payback would be just a few days for the belt upgrade.”