January 5, 2011
by Christina Fisher
When it comes to hydraulic breaker maintenance, proper equipment operation is as important as routine preventive maintenance. These two factors work simultaneously to keep a breaker operating at peak efficiency with minimal downtime.
Operator training: back to basics
“When I conduct a seminar, I really stress operator training,” says Jeff Graham, technical support representative for Atlas Copco Construction Equipment. “Improper operation can really destroy a breaker just as much as a lack of maintenance.”
1. From the outside to the inside. Don’t start breaking in the middle of the material. The breaker may not be able to break the rock very quickly. The working tool could get lodged in the material or overheat. It’s like eating a sandwich. You don’t start in the center; you start at the outside and work your way in, taking small bites to work your way into the material. Starting in the middle will increase the likelihood of extended cycle times.
2. 90 degrees, please. Always work 90 degrees to the work surface. (This is not the same as 90 degrees to the ground!) When an operator works at an angle, the tool is put under stress and can break.
“This is why we put breakers on excavators,” Graham says. “The excavator can angle the breaker in different directions so that you can obtain that 90 degrees to the work surface of the material you’re working on.”
3. They’re breakers, not drills. Never place the breaker straight down into the material like a drill, which can cause the tool to get wedged into the material. Instead, slightly rock the breaker 5 degrees in either direction. This allows the dust and debris to come out of the hole in order to easily remove the tool when you are ready to move.
“You rock the breaker to find the sweet spot,” Graham says. “It’s like playing golf. There’s a certain spot on your golf club that you want to make sure you hit to get the most power and the farthest drive out of your hit. It’s the same thing with a breaker. By finding the sweet spot, it reduces the amount of wear on the bushings and allows the breaker to work more efficiently.”
4. Break, don’t pry. Never pry material apart with the breaker. It’s not designed to break by prying, which can damage the tool. Instead, break larger material up into smaller pieces.
5. No progress? Time to move on. One of the most important things an operator can do is to avoid extended run time. “This is a common error,” says Matt Cadnum, vice president of aftermarket for Atlas Copco Construction Equipment. “Our specs indicate a run time of no more than 30 seconds in any one place, but a good rule of thumb is that if the material is not breaking in 10 to 15 seconds, then the operator should reposition the working tool.”
A lack of progress also indicates that the breaker may be improperly sized for the material. “When the debris and dust stop coming out of the hole and settle at the bottom, the tool is actually beating on the dust,” Graham explains. “The breaker is not transferring its energy from the tool to the material. Breaking power is decreased, and you lose that energy. That lost energy is turned into heat from the friction. This heats up the end of the tool and starts to distort and destroy it.”
This excess heat can also damage the auxiliary hydraulics on the carrier because it’s working harder. “The carrier is only designed to handle a certain amount of generated heat from the attachment,” Graham adds. “If you run the breaker for long periods of time, you can overheat the carrier as well, and the cooling system for the carriers won’t be able to handle it.”
Maintenance: All day, every day
By putting some simple steps and procedures into practice throughout the day, an operator or technician can keep a hydraulic breaker operating at peak efficiency for longer periods of time.
Each morning, visually inspect the breaker and the carrier. Make sure nothing is cracked and that the hoses are intact and properly attached. The most important thing an operator can do, however, is to ensure that the breaker and the tool are greased properly.
“Several times a day the operator should draw the tool up near to him so he can see the tool and the bushing. He doesn’t even need to get out of the cab,” Graham says. “The operator should see wet black grease. If the tool looks grainy or powdery, then it’s very dry and not getting enough grease. If the tool is shiny, it’s not getting any grease at all.”
At this point, the equipment needs to be shut down to determine what is causing the lack of grease, whether it has run out of grease, a grease hose has broken, or the central lube system is malfunctioning.
“Many customers in the field don’t realize how critical it is to lubricate the bushing and the tool, so their operators don’t do it,” Cadnum says. An automatic lubrication system, available on some breakers, prevents damage due to improper lubrication.
A breaker should be lubricated every two hours at a minimum. A breaker cannot be over-greased unless it’s done improperly. Whenever a breaker is being greased, there needs to be down pressure on the tool so that the grease will not be forced up into the impact area of the tool and piston. The grease should travel down the tool to the area where the bushing is and exit the breaker.
Graham says that operators often ask how much grease should be used each day. “Different applications call for different amounts of grease. Longer cycle times mean more grease. If the material is light and it doesn’t take much to break through it, then less grease is needed. It all depends on the material,” he says. “The most important thing to do is to check the tool multiple times a day.”
It’s not just the lubrication process itself that is important, however. It’s using the proper type of lubricant. “Using an off-the-shelf grease won’t work,” Cadnum points out. “You need something specifically made for hydraulic breakers. The stresses are such that the machine is very demanding and its needs (are) very specific. The amount of friction, side loading, and heat on a breaker requires a tough lubricant with a high dropping point, and usually some solids added as well.”
Many manufacturers offer a type of grease with copper particles added to it. When all of the grease is pushed out of the breaker, the copper particles act like miniature ball bearings, providing some lubrication in a binding situation.
It is also important to regularly check that the breaker and the carrier are properly adjusted. “Most hydraulic excavators allow the operator to adjust the hydraulic input to the breaker right from the cab,” Cadnum says. “It’s extremely important that the operator understands what setting is appropriate for that hydraulic attachment. If the setting is incorrect, it could damage the breaker.”
Graham adds that when a breaker is moved to a different machine, the carrier needs to be flow tested and properly adjusted for that breaker. “Otherwise, it can really reduce the life of the hydraulic seals inside the breaker. Anytime the breaker has been rebuilt — and annually, at a minimum — the carrier should also be flow tested and adjustments made as necessary.”
Proper storage is essential
Finally, at the end of the day, the breaker should be stored standing upright. This takes the weight of the piston off the seals. Storing in this position also helps to keep rain from getting into the vital areas of the breaker. The shiny surface of the piston is exposed when the breaker is not running, and if the breaker is lying flat, water can sit on the piston and cause it to rust. If it’s not feasible to stand it upright, the best alternative is to elevate the bracket end of the breaker that attaches to the machine. Place a tarp over the tool end of the breaker to protect it against the rain.
Breakers can be very expensive to repair. However, “if you’re doing your routine maintenance and operating the equipment correctly, you should be able to schedule repairs when you are ready,” Graham says. “The whole idea is to ‘pick your downtime.’”
For the Aggregates Manager Digital Edition of this article, which includes photos and illustrations of proper techniques, go to http://www.digitalmagazinetechnology.com/a/?KEY=aggregatesmanager-09-12december#page=33.
This article was written by Christina Fisher, public relations manager of Ellenbecker Communications,on behalf of Atlas Copco Construction Equipment.