Januari 19, 2017
welcome to the first part in our mech minutestiming belts and pulleys series. over the next few videos, we’ll be covering the basicsand most frequently asked questions when it comes to choosing, installing, and using timingbelts and pulleys, and similar power transmission systems. in this episode, we’ll be discussingbelt selection for power transmission systems, taking a look at timing belts, v belts, flatbelts, and chains (for chain and sprocket systems).before comparing each system for pros and cons, several elements need to be consideredin any application when deciding on a type of power transmission: overall system or packagesize, environment considerations, and application specific requirements, including food gradeor food safe requirements, and anti-static
or conductive systems for electronic applications.important operating environment considerations include environmental temperature (both extremelyhigh and low temperatures, which can create problems for belts), large dust particlesor debris (increasing belt tension and adding excess wear to the belt), and, depending onthe belt material, grease or oil exposure, which can cause the material to break downmore quickly than normal operation (urethane belts are better in these environments). also,if there is any chance of your belt and pulley operating in the presence of ozone gas, aurethane or rubber belt with an ozone block chemical may be less prone to material degradationfrom ozone, as standard rubber belts may eventually exhibit similar breakdown characteristicsas high temperature environments. while these
are some of the more common operating environmentconcerns, make sure to evaluate your application for any others.with the application environment taken into consideration, let’s look at the differentstyles of belts and the pros and cons of each. before diving into belts and pulleys, a commonpower transmission system is the chain and sprocket, which works well for longer lengthapplications (by adding more links), has a low start-up cost, can be used in conveyancewith lugs, and works well in extreme temperature ranges. there are, however, a few downsides,including metal-on-metal contact (causing more wear and noise), the necessity of lubrication,and more frequent maintenance periods. using a belt and pulley system can help tominimize these issues, as they typically require
no lubrication and longer maintenance periods.friction systems like flat and v-belts can be cheaper belt options, however due to theirconstruction, have lower efficiency, generate heat, and have lower power generation thantiming, or synchronous, belts. v-belts do operate with lower noise which can be an importantfactor to consider, and flat belts are usually the most cost effective belt option available,but both types, being friction systems, require the highest belt tension, and may cause excessloading on the bearings and overhung load on the pulley shafts. timing belts maintainsystem timing better through the use of a toothed profile and toothed pulleys or sprockets,and typically have a higher power density, allowing for smaller belt and pulley packagesfor a similar load. because of these improvements,
timing belts are also usually a more expensiveoption, so carefully evaluate all requirements when choosing a belt type.as mentioned before, the operating environment may cause some issues with the belt, especiallyin temperature extremes, but if you’re using it in an approved temperature range, usinga belt and pulley system may be your best bet, and for applications which require superiortiming and load or power transmission, a timing belt is the way to go. already have a beltand pulley system, but are concerned about when to replace the belt? our next episodewill go in depth into typical belt wear signs and can help you diagnose imminent belt failure.
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