January 5, 2011
by Jerry R. Fifer
“Maintenance? It’s our top priority!”
Everyone talks about keeping equipment in excellent shape and how important it is, how it saves money, and how it increases operating time on the job site. Today’s economic realities demand using every trick of the trade in order to make equipment last longer while squeezing every excess expense — including purchasing new tools — out of the balance sheet.
Service professionals know the dirty secret: saying proper, by-the-book maintenance is a priority is a lot different than actually doing it right and making a difference in the life of your equipment.
Take breakers as an example. When it comes to keeping breakers running right, the most common maintenance gaffes that cost companies both in tool wear and big money for replacements come down to four basics.
1) All grease is the same, right? No, it’s not!
The Fault: Breaker tools or points become extremely hot (as high as 400 degrees Fahrenheit or more) when in use. At those temperatures, kiss standard lube grease goodbye: it will liquefy and run off the tool or actually burn up entirely. You’re left with a shorter lifespan for your tools’ bushings and broken tools.
The Fix: Spring for the good grease. Breaker grease should be, at minimum, #2 lithium-based grease containing 3 percent molybdenum. It should be rated to work at temperatures of at least 500 degrees Fahrenheit or more. Why is the molybdenum a must have? It helps the grease stick to the tool and not run off.
2) Where do I grease it?
The Fault: You may have the best grease, but failing to put enough on and applying it in the wrong way can be just as bad as using low-quality product.
The Fix: Start with a quick examination. When the breaker is raised vertically off the ground, the tool will drop down and expose the portion that is in contact with the lower tool bushing. The condition of this exposed portion is indicative of the condition of the upper, unexposed sections. The exposed portion should be thoroughly covered with grease.
How do you apply it? Use an automatic greaser (if available) and set it to apply grease only when the breaker is operating. If the automatic greaser runs while the breaker tool has dropped down, grease will be deposited on the top of the tool. The next time you use the breaker, the grease (now trapped between the top of the breaker tool and the bottom of the strike piston) will be forced through the lower piston seals and damage them. If applying lubricant manually, the tool must be pushed upward into the breaker before greasing. This is easy to do by lowering the breaker vertically and pressing the tool against the ground.
The bottom line: using the proper amount of high-quality grease and putting it on in the correct manner will greatly reduce the friction wear on the tool and tool bushings.
3) When is it time to inspect?
The Fault: Tool tops not checked regularly lead to more damage overall.
The Fix: The top of the tool takes a tremendous beating from the strike piston. Eventually, the tool top’s surface will mushroom just like the top of a mechanic’s cold chisel or punch. It is important that the mushrooming areas be filed off before they become so large that they break off. Broken pieces of the tool can get trapped between the tool and the strike piston, resulting in piston damage. Also, be sure to check for damage on the areas of the tool that strike the tool retainers. Any mushrooming or other faults must be filed off regularly.
An important reminder: different types of breaker applications will result in more or less tool damage. Inspect and service the tool once a week until experience teaches you how long your service intervals can be.
4) When do I replace the bushings?
The Fault: Wear limits on bushings are routinely misjudged, resulting in piston damage and shortened lifespan on other parts.
The Fix: All breaker tool bushings have a specified inner-diameter wear limit. When this limit is reached, most bushings appear to have plenty of material left to wear off and are usually not replaced as recommended. But the key is to remember that the wear limit is not based on how much material is left, but on the possible angle of engagement between the tool and strike piston. The lower bushing will be the first to wear out. If it is allowed to wear past the limit, the tool can be at such an angle to the piston that the piston only hits the tool on the edge of the strike surface. Continuing to operate the breaker in this way will damage the strike piston. In addition, wear on the upper bushing is accelerated when the lower bushing is worn out. You can extend the lifespan of the upper bushing by replacing the lower bushing when the wear limit is reached.
Why risk down time, lost job opportunities, and uncontrolled spending to replace worn equipment? Spend a little time and money on the simple fundamentals and the results can pay off for a long time to come.
To view this article in the Aggregates Manager Digital Edition, which includes photos and illustrations, go to http://www.digitalmagazinetechnology.com/a/?KEY=aggregatesmanager-10-06june#page=25.
Jerry R. Fifer is Tramac’s technical support manager in the Southeast. He can be reached via email at email@example.com.