Improving efficiency in belt drive systems

Replacing V-belts with synchronous belts in air handling applications has been recognized as a best practice to reduce energy requirements in industrial and commercial applications, according to a recent report from the US Department of Energy.

Why are synchronous belts are considered ‘green’? At the time of installation, V-belt drives run at 95%-98% efficiency. Those percentages will decline to approximately 93% over the life of the belt if it is properly maintained. Most efficiency losses occur in the first 24 hours of operation, creating the need to re-tension the belt. If V-belt drives are not re-tensioned as part of a preventive maintenance program, they can drop to as low as 80% efficiency during the life of the belt.

Efficiency as applied to air-handling equipment is the rate of the motor’s energy as transferred to the driven fan. The lower the efficiency rating, the slower the fan speed, which results in less air movement and longer cycle/run times for the HVAC equipment — thus increasing electrical energy consumption.

Once properly tensioned, synchronous belts will maintain a 98% efficiency rating throughout the life of the belt, without the need for costly maintenance. Electrical savings due to the constant 98% efficiency standard of a synchronous belt are significant in many applications.

What is the annual energy and dollar savings if a 93% efficient V-belt is replaced with a 98% efficient synchronous belt? The Department of Energy report compares a continuously operating, 100- hp, supply-air fan motor at 93% efficiency, which runs at an average load of 75% while consuming 527,000 kWh annually. Electricity is priced at $0.05/KWh.

Energy Savings = Annual Energy Use x (1-93%/98%) = 527,000 kWh/year x (1-93/98) = 26,888 kWh/year. Annual Cost savings = 26,888 kWh x $0.05 = $1,345.

Not all synchronous belts are the same. For example, Jason Industrial Platinum offers Dual Core Cord technology, which maintains extreme dimensional stability under tension, allowing narrow widths that fit within existing belt-drive applications. Also, its RPC tooth profile supplies a 98% efficiency rating under less tension than V-belts.

Synchronous belts improve efficiency and save energy on most drive setups, however, they will not produce energy savings in every application. Smaller drive applications with short centre distances tend to use V-belt slippage to ramp up fan speed. Switching to synchronous drives in these applications can possibly increase electrical consumption.

Synchronous belts reduce bearing and shaft loads up to 15% for longer life and less wear. They run cooler than V-belt drives, increasing bearing life. In addition, Jason’s Platinum belt features HNBR rubber-based technology to reduce noise levels; offers a wide range of operating temperatures, from minus 30°F to +240F°; and has a fabric-covered tooth surface that improves torque-carrying capacity and tooth shear resistance.

Jason offers a drive design manual to assist with the procedures and calculations required to convert V-belt drives to synchronous belts, as well as a design engineering group to help with the process.

Craig Roozen is director of diversified products with Jason Industrial. 

Find the original article on the MRO website.