Newer designs incorporate many simple but highly effective engineering improvements.
In 2014, the Society of Tribology and Lubrication Engineers (STLE) embarked on a study to identify new trends in our industry. Cited by many STLE members in the study was the trend toward mechanical systems that are more reliable and require lower-cost maintenance. Examples include better corrosion protection, lube-for-life bearings, etc. Now I recognize that more than a few of you might be exclusively urbanophiles, but for the agrarianly-inclined, the application of these new trends is an exciting development of great importance to society that reveals how we overcome tribological challenges in a cost-effective manner.
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A manure spreader manages a significant hygienic issue in an ecologically sound manner by recycling nutrients to the soil and increasing the amount of topsoil so more nutrients can be grown to feed livestock. Accumulated manure can pose serious run off problems, cause bad odor, result in bacterial, fungal and insect infestation and have a displeasing landscape. This is not trivial as the average horse generates 25 lbs. of manure per day, plus any urine-soaked bedding, leftover hay, etc. You can soon create a small mountain of very biologically live material in no time at all—which is great for the garden and flower beds. For people with livestock, this task is carried out 24/7, every month of the year. Figure 1 shows a manure spreader in action on a good day—it is only lightly raining.
So what about the tribology of a manure spreader? As you can see, it is essentially a two-wheeled wagon. In the older designs, the wheel bearings are sealed from the manufacturer and, thankfully, require little maintenance—that’s just about all the good news.
In Figure 2, looking into the bed, we see two chains on either side with simple angle iron pieces spaced evenly running from chain to chain. As the chain is pulled toward the back of the wagon, the manure is fed slowly into whirling paddles that spread and disperse the manure evenly out the back.
Living on a farm with more than 20 horses, this is a topic I know a bit about firsthand. However, my own manure spreader died an unceremonious death during -15° F weather several years ago. I bought a new spreader of the same model from the same manufacturer and noted a 20 percent higher price.
However, when the new spreader arrived, I was pleased to see the engineering improvements that nicely meshed the trends we identified in our study. Examples are better corrosion protection, lube-for-life bearings and a more robust chain design. So it struck me that it might be worthwhile to share a few of these changes to illustrate the point of STLE’s emerging trends study.
First, the chains on the old system are inexpensive metal stampings. This means that they have relatively sharp edges that preclude coatings or most lubricants to protect them from corrosion. Further, the bearing surfaces are also rough, adding to friction and wear (see Figure 3). The new chains are made from rod stock so the only rough edges are on the cut ends (see Figure 4), thus they have an inherently more corrosion-resistant shape and better bearing surfaces.
The older chains have another remarkable property. They only seem to break at below 20° F, especially if it is windy and snowing. As time goes on, constant exposure to the elements, manure, urine and wet bedding eventually corrode and weaken the chain. The stresses of winter put more strain on the chain, further increasing the probability of failure.
Repair is simple enough: the tension on the chain is released, the chain is bent into position with just a few light taps of a hammer, the old link is removed and the new one installed. This repair, of course, happens only out in the field and only on a cold, windy, snowy day—during daylight if you’re lucky. The manure must first be dug out of the spreader, by hand, to access the chain. The light taps of the hammer are actually a bare-handed, knuckle-busting, operation that takes only a few seconds. However, the new chains are thicker, so it will take longer for wear/corrosion to do their damage. Also (and most important) they interlock simply, which can easily be done with a gloved hand. The new chains also are relatively inexpensive.
Learn more about manure spreader tribology
This article is excerpted and reprinted with permission from the February 2015 issue of Tribology and Lubrication Technology (TLT), the official magazine of the Society of Tribologists and Lubrication Engineers, an international not-for-profit technical society headquartered in Park Ridge, Illinois. Read the full article at stle.org.
About STLE
The Society of Tribologists & Lubrication Engineers (STLE) is the premier technical society serving the needs of over 12,000 individuals and 250 companies and organizations that comprise the tribology and lubrication engineering business sector. STLE members are employed by the world’s leading corporations, academic institutions and by governmental agencies dealing with science and technology. STLE supports these distinguished technical experts with a variety of professional education and certification programs.
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