It can be easy to look at the heavy-gauge steel and the massive horsepower that chippers possess and think they’re indestructible. Chippers are incredibly tough — they need to be to stand up to the extreme duties they perform — but they’re still machines at heart, powered by motors and pumps, belts and bearings. If you think of your chipper as just a big block of steel, that’s probably what you’re going to end up with. For it to perform the way it was designed, you need to maintain it properly.
Bruce Bartling, sales manager with Cal-Line Equipment in California, conducts regular chipper maintenance trainings on the West Coast. His company is a dealer for Bandit Industries, but Bartling says that, when it comes to chippers, many maintenance tasks are the same regardless of brand. Blade maintenance, for example, which he says is one of the most important chipper maintenance tasks. “That’s the heart of the machine,” says Bartling. “A chipper is a cutting device, so everything has to be sharp to work properly. If it’s not cutting properly, you can have a lot of associated problems that you may not think are related. It may not pull in the material the way it should; it may bog down the engine – everything is just having to work harder.” He compares it to using a chain saw with a dull chain: a chain saw (or chipper) can be brand new and have plenty of power, but if it’s not sharp, it could be outperformed by an older, smaller unit that is sharp.
How to know when sharpening is required? The answer to that depends on what’s being chipped, and how careful the crew running the machine is. For starters, hard, dry wood will wear blades out faster than soft wood. Constantly chipping big wood also speeds the wear process. Finally, “a lot of time, the wear on the blades can be caused by getting dirt and rock in there; crews are raking stuff up off the ground and not realizing they’re getting that stuff in with the wood,” says Bartling. The cutter bar or anvil can also be worn down this way, though more slowly. “It will round off, and it needs to be a square edge,” he says.
Chipper knives and anvil or bed knives are often overlooked in terms of maintenance, says Casey Gross, product sales manager at Morbark. “Often we see customers flip their chipper knives, or install new ones, then overlook setting the anvil or bed knife to the chipper knife,” he notes. “In order for the anvil or bed knife and chipper knife to work at optimal performance, it is important to ensure the anvil or bed knife has a 90-degree cutting edge and is properly adjusted to the chipper knives.”
Fluids, filters and more
Gross says there are many critical components on a chipper, including the engine, driveline, chipper disc or drum and the hydraulic system. “While it important to maintain all of these systems, the most overlooked is the hydraulic system maintenance,” he states. “The hydraulic system is the heart of the chipper’s operating system to run the pumps, motors, valves and cylinders. It is often overlooked because as long it is working, it is out of mind.”
One relatively easy way to keep this system running smoothly is through regular filter changes. “While changing the hydraulic fluid is not always necessary, periodic filter changes would benefit these systems greatly to avoid contaminants from damaging the hydraulic system components,” Gross explains, noting that some dealerships have the technology within their service departments to flush and recycle the existing oil to reduce the costs replacing the oil. Of course, it’s also important to regularly check and change engine oil and oil filters.
Some of the other most-overlooked maintenance items involve the engine air intake system, says Lucas Graham, lifecycle manager with Vermeer. On a basic level, that means inspecting the air cleaner filter restriction gage (if equipped). “If your machines don’t have a restriction indication, carefully remove the air cleaner cover and inspect the air cleaner element. Make sure to pay special attention to ensure it gets reinstalled correctly,” Graham advises. He says it’s also important to inspect the charge air coolers that have been added to many Tier-3 engines. “The charge air coolers can triple the number of intake hose connects compared to a normally aspirated engine. Each of these connects needs to be inspected, along with the tubing and elbows for cracks, loose hardware, and proper sealing on a regular basis.”
While some of this type of maintenance is best done in the shop, there’s plenty that a crew can do even out in the field. “Things like cleaning the air filters and keeping the radiator clean are really important,” says Cal-Line’s Bartling. “Greasing is something you definitely need to be able to do. And when it says ‘daily,’ it’s referring to eight hours of use,” Bartling emphasizes.
Scott Turney, fleet and facility manager with Graf Tree Care in Illinois, says that as a reminder about the importance of greasing, he printed pages from the manuals of the chippers the company uses showing all of the grease points and hung them on the wall of the shop. “Those have to be checked and greased daily,” he reiterates. In fact, that’s one of the maintenance items that Turney asks crews to check when they’re out on jobs during the day. “I equipped every chipper we have with a toolbox and a grease gun,” he explains. “If the chipper is running all day long, they can check it mid-day to make sure the grease is OK.”
One note of caution: “For some bearings over-greasing can be just as damaging as not greasing enough,” says Vermeer’s Graham.
Other things to keep an eye on
“There aren’t a whole lot of moving parts on a chipper, but what does move is key,” says Bartling. That means keeping an eye on things like hydraulic relief pressures, clutches and belts. Particularly on larger chippers that are handling bigger material, “you need to make sure you stay on top of your clutch adjustment, or you can burn your clutch up very easily,” he says. “On a brand-new chipper, it’s all set, but then you have a break-in period where you need to stay on top of it.”
Moving beyond the chipper itself, trailering maintenance is overlooked, says Bartling. There’s a lot of weight on a single axle, for instance, and the heavy use can eat away axle bearings. “That’s something that nobody ever looks at,” he says. “Yearly, depending on how far you’re driving, those should be opened up and repacked. But a lot of times people won’t do anything until there’s a problem. We see chippers every so often on a flatbed because the wheel came off.”
Turney with Graf Tree Care advises checking trailer wheels on a weekly basis to see if the bearings are loose, noting that he has heard of one instance where a bearing seized up and the wheel broke off, creating a bad accident.
It’s important to uncouple the chipper from the truck each night, and then reattach it in the morning, Turney says. Leaving the chipper hooked up all night “puts unnecessary wear and tear on the truck springs,” he points out. “Check the lights daily, and the trailer plug that plugs into the back of the truck. And, if you can, if you’re in an area where it’s salty during the winter you should rinse off the trailer — and the whole machine — daily to help prevent corrosion.”
On that note, Turney makes clear that cleaning the chipper is part of maintaining it. That includes checking the chutes at the end of each day: “You need to look for any debris that’s left in there; when it’s wet, it soaks up water just like a sponge. First, it can create a jam if gets too big. And, second, it can cause corrosion if it’s overlooked for a period of time.”
Graham adds that it is important to take time to clean off any accumulated wood chips and sawdust inside the engine compartment, as well as around the fuel tank fill neck and electrical connectors. “I recommend starting with a leaf blower first, since the lower air pressure has less force and will prevent forcing dirt and moisture further into bearing and electrical components compared to high pressure air, or pressure washing,” says Graham.
Finally, for late-model chippers equipped with EPA Tier-4 Final diesel engine technology, there may be some additional maintenance chores to perform.
“Operators may have Diesel Exhaust Fluid reservoirs to maintain and, depending on the engine manufacturer, Diesel Particulate Filters to watch over,” says Gross with Morbark. “It is important to understand how these systems work to ensure the engine continues operating at peak performance.”
Keeping track of it all
Gross says a great way to keep up with maintenance is to make it a daily part of the job. “It is important for operators to do a daily maintenance check and walk-around of the chipper every day before operating the unit,” he states. “A quick five-minute trip around the machine each day could save thousands in unnecessary repair costs.” As noted earlier, this walk-around should include an inspection of things like the trailer-to-truck connections, trailer lights, clutch engagement, drive belt tension and chipper knives, as well as a check for loose bolts, fasteners and fittings, or damaged hydraulic hoses.
Maintenance should be tracked on a log for each chipper, documenting the date and the number of operating hours at the time of each service. Gross says this can be done the old-fashioned way on paper, or on a smartphone or tablet, which can also be programmed to send reminders about specific maintenance when it’s needed.
Keeping up with maintenance pays off both in terms of the performance and longevity of the chipper, and the safety of those operating it, says Gross. For example, the poor feeding performance that results from dull chipper knives “may result in operators performing unsafe work practices such as trying to kick material into the machine,” he says, noting that operators kicking material into a machine feet-first accounts for 48 percent of chipper-related injuries and deaths. “With the root cause being poor maintenance, these accidents are completely avoidable.”
“The number one concern with not performing regular chipper maintenance is safety,” agrees Graham. But the other major reason to keep up with maintenance is also crucial to any tree care business, he adds: avoiding significant unplanned machine downtime for a major repair.