Drive belts may rebel: keep them under control with these helpful tips

Consider some of these ideas to keep your drive belts from revolting

By Russ Kratowicz, Executive Editor

Drive belts are items that really ought not to be ignored. Sure, in terms of sexy, they can’t compete with digital technology to get your attention, but they’re still important. Assuming your best practices endow them with good alignment and tensioning, a power transmission belt generally wears either from having to transmit large loads or from being left in service long past its normal life expectancy. With so much attention being focused on the idea of industrial reliability these days, your maintenance department might want to consider using horsepower-hours as a performance indicator for monitoring belt life.

V-belts, cogged V-belts and synchronous belts each have a different cost structure and relative operating advantages. In general, synchronous belts are the most efficient, while V-belts are the most commonly used. Depending on your circumstances, a change to synchronous belts across the board might prove to be a lucrative move. One of the sites we found shows the calculations.

There are many more tips you can glean from this month’s slog through the digital morass we call the Web in search of practical, zero-cost, noncommercial, registration-free resources that can help you improve your plant’s bottom line. Remember, we search the Web so you don't have to.

Technical information

Kelly Bramble, president of Engineer’s Edge in Monroe, Ga., wants to provide you with information that can help you solve typical and complex problems in a variety of technical disciplines, but we’ll focus on matters related to belting for power transmission. Let’s start exploring Bramble’s nugget by zipping ye olde mousie to www.engineersedge.com , a densely linked home page. Once there, click on “Vee and Flat Belt Design Data” shown in the right-hand column. This will give you access to a dozen links that open up tables and graphs related to belt sizes, applications, pulley groove sizes, tensions, torques and power, standard sizes and sheave diameters, service factors, design horsepower versus service factor and flat belt calculations.

Access more of Bramble’s belt information by clicking on “Engineering Calculators,” which appears at the top of the home page. Keep your eye on the center column as you scroll down to “Motion Control Design.” Click on “Motor Driving Speed Reducer” for the equation and online calculator to determine the torque and force to drive gear, belt or chain mechanical systems. While you’re at it, you might as well spend a few moments examining the other offerings Bramble provides.

From Down Under

Even if V-belts don’t really rotate in the opposite direction when you’re south of the equator, they’re still transmitting power in Australia. The School of Mechanical Engineering at the University of Western Australia offers an online tutorial about belt drives that should prove to be of interest. It covers drive geometry, kinetic effects, the relationship between belt fatigue and life expectancy, selection tips and a bit of information about traction mechanics. Because the posting is intended to be a teaching tool, it includes problems and their solutions. You might want to consider using this material as the basis for your in-house training. Waltz Matilda Mouse down to www.mech.uwa.edu.au if you want to get the goods. Enter the phrase “V-belt drives” in the search box in the lower right corner of the screen. When the page loads, the specific entry I’d recommend that you examine is titled, “DANotes: V-belt drives: Index of topics.” From there, navigation becomes intuitive.

More from the Aussies

Victoria is the province at the southern tip of the island continent and Sustainability Victoria is a provincial program that focuses on using resources efficiently and minimizing human damage to the environment. The program is inclusive in that it covers homes, offices, schools and industry. When it comes to energy efficiency, every little bit helps and, whether or not you believe it, V-belt performance affects overall energy efficiency. That’s why the Victorians offer a bit of help with a toolkit that you can access at http://www.sustainability.vic.gov.au. Click on “Take action” at the top center of the screen. Then, click on “Energy and greenhouse management toolkit” under “Business and Industry” at the far right side. You’ll want to open Module 5 and perform a search for “Efficient belt drives.” This will yield information about available belt drive types, their benefits and belt maintenance tips, including a troubleshooting guide. The latter element might work well for root cause analysis when belts start giving you a problem.

Downloads

The ability to exploit some stranger’s programming skills to solve your current problem is one of the beautiful aspects of digital life on the Web. Using the many downloads available should enhance your productivity, if not make it a bit easier for you to run in place vis-à-vis your competition. If you feel comfortable with downloads, you might consider MITCalc, the work product of Ing. Miroslav Petele in the Czech Republic. This site has a collection of Excel-based calculations for solving a variety of engineering problems. Because of its open format, you can freely modify the spreadsheets to suit your particular needs. As you’d expect, one of Petele’s downloads addresses V-belts, and accessing it is simple. Pop over to www.mitcalc.com and click on “V-belt.” Then, click the “Download” link on the left. Finally, skip the registration section and scroll down to the standalone calculations, where you’ll find the download link. The demo package self-installs on your machine and expires in 13 days unless you purchase the authorization code. To run the software, you may need to reconfigure your settings to accept popups. When you’re finished, the software’s uninstall option simplifies digital disposal.

From the makers

Standardization is the reason you can mount a belt purchased from one vendor on a sheave you got from another and then continue mixing and matching pretty much indiscriminately. Well, somebody must be keeping track of the applicable standards and I think it might be the Mechanical Power Transmission Association in Naples, Fla. Although these standards are aimed more at the manufacturers that produce belts and sheaves, they’re available to us commoners if you go to the organization’s Web site, www.mpta.org. The offerings include standards that cover pulley balance, surface finish and dimensional tolerances. Also, the site has calculations for quantifying the stresses that occur in the radial arms of large sheaves and a primer on balancing rotating objects. That last feature might be of some value to your organization. Go to the group’s Web site and click on “MPTA Publications.”

Precise is sehr gut

Even if you don’t agree that the Germans have a reputation for excellence in engineering and manufacturing, you’ve got to admit they make some mighty fine vehicles for traversing the Autobahn. German apprenticeship programs involve a lot of classroom and on-the-job training, which isn’t exactly a bad thing when it comes to industrial competitiveness. To get a flavor for what faces someone wanting to enter the trades in Germany, just take a look at the Online Library for Vocational Training developed by Deutsche Gesellschaft für Technische Zusammenarbeit (Eschborn, Germany) or CRYSTAL, the Network for Training and Learning Media. This is a prodigious work that includes more than 370 online instructional books covering everything from the proper way to remove metal with a file to carpentry and power tools to a complete course on internal combustion engines and way beyond. And, yes, there’s content covering V-belts. Send your most precise and exacting desk rodent to http://crystal-netbook.info.

The Whole Building Design Guide is where you can obtain building-related guidance, criteria and technology, all from a “whole buildings” perspective. The information comes from federal agencies, industry, non-profits and educational institutions. Because our tax money paid for at least a part of the material WBDG assembled, you might as well see what we bought. Point your trusty browser at www.wbdg.org  and perform a search by plugging “MO 114” as the argument in the appropriate space in the upper right. When I did this, “MO-114 Volume 3 Maintenance and Operations of Ventilation Systems” was the first citation to appear. It comes from the Naval Facilities Engineering Command in Alexandria, Va. I direct your attention to Sections 2.7 and 2.8, which cover belt-drive fans and starts on page 2-12. You’ll learn something about sizing sheaves to achieve specific performance and the energy consumption associated with changing sheaves after the fact.

Ivory Tower ROI

The University of Michigan’s Industrial Assessment Center is funded by the U.S. Department of Energy and appears to serve as an aggregator of information intended to help small- to medium-sized manufacturers reduce costs, energy consumption, waste and pollution while increasing productivity. One of the content elements on the Center’s Web site was published by the Office of Industrial Productivity and Energy Assessment at Rutgers, the State University of New Jersey. The document in question is titled “A Self-Assessment Workbook for Small Manufacturers” and recommends that you replace the drive belts on large motors with high-torque belts or energy-efficient cog belts. To buttress this call to action, the document provides the calculation you can use to prove that a more costly belt can increase overall efficiency enough to generate an acceptable return and payback period. If you’re interested in this sort of continuous improvement, enroll your mouse in http://umich.edu and search on the term “IAC.” The first citation will probably be the one to access. When it loads, click on “Toolbox” on the left side, then click on “Self Assessment.”

Without comment

www.nrel.gov/docs/fy05osti/37502.pdf

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