Keeping the Moving Parts Moving

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Gx Bug Web
Gx Bug Web
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Gx Bug Web

Maintaining an excavator’s moving parts (stick and boom, tracks, chassis, bucket and attachments) isn’t rocket science. But it takes time, attention to detail, and being diligent about following manufacturer specifications. Maintenance is critical. Read the manual, schedule according to manufacturer-recommended intervals, operate your machines properly and do visual inspections daily to catch small problems before they become big ones. You’ll be a long way ahead of the game.

Make Maintenance a Priority
“It comes down to how you want to operate,” says Armando Najera, excavator product manager at Komatsu American Corp. Are you willing to take a failure here and there for the sake of what you think of as productivity, or are you aiming for zero downtime because you know in the end downtime costs a lot more than changing filters or oil or hydrologic fluid a little earlier than you need to?

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“Equipment and components are so well designed today,” says Najera, “you probably can get along with a philosophy of “˜catching it next time,’ but you’re sacrificing useful life. Some companies are very good at tracking what needs to be done-maybe they’ve found hoses failing at 400 hours so they’ll change them at 250. They know if something fails, the downtime required to bring in another machine is substantial plus a crew sitting around doing nothing. In that context it’s no big deal if you’re losing 100 hours of useful life on a hose.”

“The excavators we produce today are much more sophisticated than 10 or 15 years ago,” says Tim O’Brien, North American marketing manager for Case Construction Equipment. “And I’m not sure maintenance practices have kept up. For example, the undercarriage and the track are now typically grease-lubricated, whereas before they were essentially dry. This adds longevity to the machines, but maintenance practices have to adjust.”

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“Operators should make sure they are up to speed on all the tools available to them,” says Chad Ellis, product manager at Doosan Infracore America. “This includes technology on the machine and dealer resources for both preventative and scheduled maintenance. Your dealer has the expertise, he has all the maintenance records and the factory-trained technicians. And when the dealer is doing the work, it’s on him if something happens.”

“The big companies will bring their mechanics in and I’ll work with them, tell them what’s important,” says Ed Deutsch, head mechanic and shop foreman at Knickerbocker Russell Co. Inc., in Pittsburgh, PA. “And then when they’re not using a machine for a week, or they have a big job coming up and don’t want any downtime, they’ll call us and ask if they can bring it in and we can check it over.”

Daily Checks-Get the Habit
The first line of defense against downtime and premature wear is daily checks. “Finding problems before they become problems is number one,” says Ellis. “It shouldn’t take an operator or a maintenance guy more than 30 minutes for a daily check and greasing.” A daily check should not be a production, says John Schrader at Fabick Caterpillar in Missouri. “It’s just taking a good look at your machine and seeing what right be loosened up or leaking.”

“You want to make sure things stay nice and tight with the boom and stick,” says Brian Coulter, general manger at New England-based Norfolk Power Equipment, “so when it does wear, you’re replacing pins and bushings, not refabricating the whole bore.”

Look for rust, says Jeff Powell at Liebherr USA. “Rust stains coming from weld areas are usually a big indicator of a crack forming in a structural component. Look for loose pins and bushings. It’s an inexpensive fix if they’re caught soon enough. If they’re worn out, the performance of the machine will be drastically reduced, and this ultimately could affect the tracks or breakage of other components down the road.”

Diego Navarro, who is the John Deere service-marketing manager for general construction and forestry, reminds operators the arm is not an unbreakable part of an excavator.

“Over the years, as the demand for hydraulic pressures has gone up, the machines have become more powerful, and this increases the opportunities for abuse. Abuse may cause a crack. The arm and boom become an extension of the bucket and need attention. Some arms and booms may develop cracks that need to be fixed in time. The utilization of heavy attachments like tree harvesters may require shortening the arm and reinforcing of both, the arm and the boom.

“The trick is to reweld as soon as a crack is observed, and if necessary add a plate. If you’re using a hammer on a machine, the hammer itself is extending the length of the arm, which puts tremendous force on the arm itself. In these kinds of situations, there should be a more thorough check to make sure there’s no fatigue starting.” For large machines, Navarro recommends annual ultrasound inspections.

“Check the bucket,” says Coulter. “Is it bent? Are there cracks? Are the teeth worn down? Keep grapples and other attachments greased. Check for leaks. And when you’re connecting and disconnecting the hydraulic lines, clean off the fittings before connecting them together or you’ll wear out the quick-coupler and cause leaks and contaminate the hydrologic oil.”

Joel Escalante. Product Competency Manager at Volvo Construction Equipment, also wants operators to check wear on bucket teeth and to keep them wearing evenly switch the internal ones with the externals. “All it takes is a lock. For $5 to $10, you save a lot of money. If you’re using a hammer, make sure there’s no leaks and it stays charged properly, and be sure to use high melting point type grease, 350 degrees.”

“You need to take a good look at the quick couplers and make sure they’re working properly, says Dean Eby, service manager at D-P Equipment Co. Inc. in Camden, MI, “because you basically have only two pins where the attachment is made, and it’s another wear point.”

Tracks are next. “The biggest thing for tracks is keeping them adjusted properly,” says Powell, “but the biggest thing I see when I go on job sites is that the tracks are loose. Some of the pins or bushings are frozen or kinked so they don’t run correctly, and this will wear out the sprockets or the undercarriage. Loose tracks also mean the rails on the undercarriage will get worn prematurely.”

Michael Aubrey, product support at IHI Compact Excavator Sales, agrees. “The biggest thing we see as far as distress on the machine is improper track maintenance. Keeping proper track tension is a big savings as far as wear and premature failure of tracks, sprockets, and undercarriage. If you’re reinstalling tracks of another brand, follow the correct sizes on your originals, or you may be faced with premature failure of your idlers and lower rollers and sprockets.”

“Raise your tracks up and check the tension,” says Coulter. “A rubber track that’s loose will wear out faster; a loose steel track wears out the pins and bushings quicker. Overtighten, and you’ll do the same thing. Make sure there are not broken links and bolts coming out of the pads.” (Eby notes that with ground speed on contemporary machines increased threefold, he sees pins and bushings wearing out faster.)

When you’re checking tracks, also check for any loose, damaged, or missing components, such as bottom rollers, loose track pads, top rollers, and track guides, says Reece Norwood, marketing manager at Kobelco Construction Machinery America. “Look down along the tracks to see if there is a section out of line, which could indicate a loose track pad or broken track pin. Stand to the side and check that all rollers are in place and in proper alignment. Check rollers, idlers, and final drives for any oil leakage.”

“Everybody in the industry says rollers are lifetime lubricated,” says Escalante. “That is incorrect. The upper roller has a plug to check the oil level every 500 hours. If oil doesn’t come out of the hole, grab the oil feeder. Do the same with the lower rollers, where the plug is on the side. And rotate your lower rollers; grab one roller from the center on the lower side and exchange it with the front one and another one from the back with another one from the center.” And from the Escalante school of hard knocks, roller oil should be changed every 2,000 hours.

Navarro points out that excavators were not designed for long-distance travel, which means operators should expect some wear on rollers and chains if they have to travel with their machine. “Very narrow shoes will be the best approach and keeping tension on the tracks appropriate. But widening the tracks (distance between tracks) also increases stability, thus increasing hydraulic power utilization. Also remember, track tension is very important for the life of the chain.”

Keep Those Grease Guns Smoking
Greasing is the biggest thing with wear items, says Aubrey. “Grease everything that’s moving, on a daily basis or every eight hours.”

Make sure it’s enough grease and that it’s getting where it’s supposed to go, says Schrader. “On excavators you’ve got remote lines so you can reach them, but very few people ever lay it down and look at it to make sure all those fittings are taking grease and the lines aren’t pinched off or a hose torn off. A lot of times the grease isn’t going anywhere. And when you’re greasing the housing bearing, remember to rotate the machine to make sure you’re getting good coverage with the grease.”

“Where, you ask, is the machine greased?” says Tom Conner, product specialist at Bobcat Co., “the answer is often “˜yes.’ The question should be, “˜Is it greased from end to end?’ All too often I see machines where they’re getting the more prevalent points, but it’s not uncommon to see a zerk or two that probably haven’t been greased since the machine left the factory.”

“Volvo recommends lubricating the swing bearing daily for the first 100 hours,” says Escalante, “After that, it’s every 250 hours. Normally, with customers, I tell them once a month because some will do 10 hours a day for five or six days. It’s easier to do it once a month than to try the track the hours. And don’t forget the joystick-lubricate it every six months. Remove the boot and add just a little bit of grease between the pivot points. A lot of people forget this, and if they get erratic function, they think it’s hydraulic when it’s mechanical because the joystick hasn’t been lubricated.”

Acknowledge Applications
Daily walk-arounds should be attended to in a way that considers the application, says Scott Emmans, product support manager at Case. “If you’re working underwater, every four hours you should regrease that portion of the attachment that’s going under the water. Water tends to flush out the lubrication, and at some point you could have deterioration of the bushings. If the machine is going to be used in water regularly at some point you might want to put an automatic greaser on it.”

Pay attention to bucket tip wear if you’re in very hard material,” says Ellis, “so you don’t end up losing the shank the bucket slips over. You don’t see that in too many applications, but there are places where you’re in hard enough rock and sandstone that it will really grind them off.”

Better than trying to make adjustments, says Emmans, configure your machine properly to begin with. “Particularly the undercarriage. If you’re in higher-impact applications such as forestry, equip it with a high and wide heavy-duty undercarriage and guard body to give it clearance and for extra guiding. Also use narrower tracks so it won’t damage or bend if you go over stump. In rockier applications you don’t need as much flotation so you also want narrower tracks. In cases where there’s a need for more traction Case can offer double grouser shoes instead of triple grouser shoes.

Norwood agrees: “Start at the beginning and configure the excavator correctly for what you’re doing. Add track guards to keep out rocks and assist guiding, for example, and remember that more demanding jobs and harsher environments require an increase in service and maintenance frequency.”

“If you’re dredging,” says Najera, “you need dual greasing before and after. And you not only grease it, you go up and grease it and come back down and grease it again, just to make sure there are no gaps you missed and it’s nice and full. You’ve introduced water, liquid, or debris, potentially abrasive material, so it’s not enough to see that the grease is coming out of the joints. You want to go up and move that joint to make sure it works its way in. You can’t afford a little air gap with grease that hasn’t been renewed.

“And when you’re in water our operator’s manual calls out lifting one side at a time and rotating the tracks to dry them out. It’s more of an issue in winter, when there’s water potentially freezing them. But if you don’t clean the tracks of mud, when it dries it will become like concrete. It’s important to maintain them, not so much because it will wear it from a link standpoint, but more from a roller standpoint in that a lot of the times they compact and keep the roller from moving. And now you’ve got a flat spot and a ruined roller.”

Escalante cautions that mud inside the compartment that houses the travel motors acts as an insulator, and the motors will overheat. “It needs to be cleaned, but people don’t pay attention.” Because final drives are very close to the ground, Navarro also reminds operators to check for water and dirt contamination, which means oil analysis.

Practice Preventive Operation
“Sometimes people forget that things they do to machines may affect the life of the components,” says Navarro. “They may have good lubrication and take care about oils and filters, but they forget about how the machine is being used.”

At Case, Emmans agrees. “Excavators aren’t designed to push dirt into a trench from the side. Although you may get away with it for a while, it’s going to cause unnecessary wear on the machine.” Connor reminds operators that rubber track machines should always cross a curb perpendicularly, rather than at a 45-degree angle. “This avoids excessive edge pressure, which causes wear. And when you wear the edge of the tracks the steel cables are exposed to moisture and sunlight and will rust.”

Keep an eye on the depth when you’re operating in water, says Escalante. “The maximum water level manufacturers recommend is at the upper rollers on the crawler frame, right up the center of the upper roller. No deeper. If the water level is higher than the upper rollers, you will expose the engine fan to water and break a blade. Also to avoid this, when you come out of the water, swing around so your rear comes out first.” And once you’re out and on level ground, check the grease bath on the swing drive. If there is water on the top, drain it. “The swing gear is designed to last the life of the machine, and under normal conditions this grease bath must be changed every 2,000 hours. But if your grease is mixed with water, change the grease right there.” And while you’re at it, use a light and a mirror to check the condition of the gear.

“If you submerged the final drives,” says Powell, “you should pull all the oil out and flush it. Not just drain it and refill it. You should drain it, refill it, run it, drain it, refill it. Because the water will start to froth up the oil, and, when that happens, it’s almost impossible to get it out by just draining it.”

Bucket size should be appropriate to the machine and the application, Navarro cautions. “Many people switch buckets for larger ones thinking they can squeeze more productivity out of the machine. But we have shown that with a larger bucket the machine may actually produce less because it takes more time to break the soil. The bucket should also match the type of soils you typically work on. We have a list of buckets and tables and charts that allow you to pick the right bucket for your machine.” He also notes that with a larger bucket, machine can sometimes become “tippy,” and some users may compensate by adding more weight to the back of the unit. But adding weight increases the hydraulic power utilization, which exerts more stress to the arm and the boom. Navarro also cautions that, like compacting the soil with a bucket, swinging the arm and boom in a side-to-side movement within a trench is also a no-no.

Also be aware, says Navarro, that while wide shoes provide better support and stability for a machine, the wider the shoe, the faster the tracks are going to wear out. “Determine what kind of work you do, and select the minimum width of the shoe you can use without sinking. Using huge shoes is also not good for the chains.

“There is a weak part in the frame where the swing bearing sits. If you add too much weight there, or if you convert the machine for a different use, the tower may suffer, because it was not designed for that added weight. Also the swing bearing is designed based on the original configuration of the machine and has limitations. Every time you add weight or increase the momentum through the arm or the boom, that bearing is going to shorten its life.”

Keep Things Clean
Wash your machines. People don’t keep their machines clean, says Coulter, and dirt and contamination get into joints. Then they go ahead and grease the dirty machine, and this wears out the pins in the joints a lot faster than it should. The best preventative maintenance for any equipment working in the dirt is to power-wash it every now and then.”

When machines come into the shop, they should be cleaned,” says Emmans. “Clean material from the tracks at the end of the shift rather than waiting until the next morning, when dirt will have hardened up. This keeps abrasive materials from wearing on the tracks and undercarriage. You can also see if you’ve got any problems.”

Escalante points out that the upper side of the crawler frame is built with a steep angle so the dirt doesn’t accumulate. “Operators should be cleaning those. Just before they go into a travel mode, they should pull out a shovel and clean the tracks because the dirt becomes like sandpaper and will wear track links, rollers and sprockets, and idlers.”

Also, while you’re at it, wash off your batteries once in a while, says Schrader. “We see machines where the batteries are in a box that is completely full of dirt, mud, just years of accumulation of junk, and then one day they curl across the top and short out, and the battery doesn’t work anymore, and everybody wonders what happened. ”

Be Aware of Personnel Challenges
Everyone agrees that if the first line of defense is the daily walk-around, the best person to do it is the operator of the machine. Coulter counsels against machines bouncing between different operators, a situation in which underqualified people could be operating (and thus checking) equipment. Schrader recommends a checklist for machines that have multiple operators and also “getting the owners and operators manual out from behind the seat and read it.” (The same suggestion was made by all the manufacturers.)

“There’s a generation of operators coming up that doesn’t have prior equipment history,” says Connor at Bobcat. “We see that in the operational characteristics of the machines. Some of the younger operators will make comments on display systems and controls, switches, and buttons more than on arm or boom control. Use the operator’s manual as a focal point and train the operator to operate the machine so that whatever actions he takes are not destructive to the machine. Also train him about preventative maintenance, and, if nothing else, an awareness of scheduled maintenance.”

“What you’re doing,” says Najera, “is putting ownership on the responsibility of doing a walk-around, teaching them to develop the habit of doing it. The mechanism that enforces the habit could be fear or economic incentive. The good operators will get there early, before they need to start, and on their own time will do the walk-around because that’s the machine they spend all day on. But then you get the guy who gets there five minutes before he has to be there, jumps in and he’s off and running. If he’s not being paid, he’s not doing to do it. So give him an extra half hour for doing that. It’s going to help you big time.”
Engine Remanufacturing“If you keep a machine long enough,” says Armando Najera, excavator product manager at Komatsu American Corp, “you’re going to need to rebuild components. I’ve seen customers who buy new machines, use them for three to five years and trade out of them. They maintain their fleet fresh. Other customers buy a machine and never get rid of it.

“That’s where the dividends pay off on daily maintenance. The weak link becomes the engine. If you rebuild the engine and if the rest of the machine has been properly maintained, you’ve maximized its value, and chances are it’s going to continue to work for you. But if you start off with a machine that wasn’t ever maintained properly, it changes the equation.”

Remanufactured products extend a product’s life cycle, says Patrick Carpenter, director of sales and marketing at SRC Springfield ReManufacturing Corp. “We disassemble every product down to the bare metal and remachine it to original OE specs. If something wasn’t done right originally—say, there was a warranty failure on a crankshaft from an engine—perhaps it was undersized and continually threw a rod—remanufacturing can produce a better-than-new quality because it considers the warranty failures inherent in the new product. And our remanufactured engines are dynamometer tested, cranked up to the same wear and tear a new engine would be.

“Remanufacturing is a value proposition if it’s the same OE quality but at a lower price point. The general rule of thumb is that remanufactured products are typically about 60% to 70% of new. So they should be about 30% to 40% less than new pricing.”

Dean Eby, service manager at DP Equipment Co. Inc. in Camden, MI, tosses another consideration into the mix. “If you go reman, chances are you’re going to get a six-month or year warranty. If you buy parts, you’re talking 90 days.”