Vegetation equipment wear and tear
It’s not surprising that for many stump grinders and trimmers, the most wear and tear accumulates on the business end of the machine.
“The mulcher or the saw for the Jarraff requires the highest amount of maintenance because there's continuous rotation of either the drum and the mulcher or the [wheel] that turns the saw blade,” Walser explained.
But despite the work they’re put through, these machines are designed to have long lifespans, as long as they’re properly maintained. Walser noted that Jarraff tries to design their machines so that they last for 8,000-10,000 hours before they need to be overhauled or replaced.
Mace agreed that the same is true for his Vermeer stump grinder, which features diesel engines with 26-56 hp, depending on the model.
“I wouldn't be surprised if there are stump grinders out there that have run into the thousands of hours,” Mace commented. This is helped by how the moving parts on a stump grinder, such as the teeth and the cutting wheel, are designed to be replaced. But to do so in time, operators and technicians need to keep a careful eye on these parts.
Preventative maintenance
For vegetation management machines, preventative maintenance has to happen on an hourly basis, with operators handling some tasks and technicians taking care of others. But for much of this equipment, Walser noted that the first 50 hours of use is a major maintenance benchmark.
“It's that break-in period, some people might call it,” he explained. “From there, a lot of [equipment] either proceed to maybe 250-hour or 500-hour [maintenance intervals] for hydraulic systems and engine types of things.”
But PMs need to happen at smaller intervals, too. Regular greasing is critical for both stump grinders and tree trimmers. For the Jarraff tree trimmer, Walser said that they ask their operators or technicians to grease the saw arbor, quad tracks, and quad track undercarriage every day.
“If we grease the saw every four hours, or the undercarriage just once a day underneath the machines, that extends the life of those components before they actually need to be replaced,” Walser noted.
For Mace, these regular duties include greasing the zerks on the stump grinder every five hours as well as blowing out the air filter with a compressed air duster. Cleaning the grinder is important, too.
“It gets really impacted with dirt and soil, so you'd want to clean the stump grinder relatively regularly,” he added, “not between every single stump, but at the end of the day or the end of the week.”
Mace then tracks these tasks in a log book, as well as any notes he has from inspecting the grinder that may eventually go to a fleet technician.
“Having a log book when you service the vehicle goes a long way, because if the vehicle goes for five or 10 hours and you go to clean it, you don't necessarily know when the last time it's been cleaned,” Mace said. “It's just a good way to keep yourself accountable.”
Inspections
As with many heavy-duty trucks, vegetation management equipment needs to be inspected every day, or at least once a week depending on usage. For the tree trimmer and mulcher, Walser said that operators need to check for basic items such as oil levels, the engine, hydraulic levels, and grease points.
“We walk around daily and inspect these items because they are wear and tear items, and as you use the machine, depending on how they use them, they might wear faster than others,” he commented.
Meanwhile, Mace said they do a visual inspection before and after every stump grind. During these, he checks the grinder or cutting disc teeth, which are made of carbide and designed to wear at the same time, for any looseness, large breaks, or other wear that could indicate it’s time to replace them. Another helpful note for stump grinder teeth is that inspections can help identify when a full set of teeth can be flipped before they’re replaced, increasing their lifespan.
“If you stay on it [and flip them] before they get to the point of severe wear, you can flip all the teeth and get another season out of them,” Mace commented.
Additionally, Mace also looks for dripping hydraulic hoses, low hydraulic fluid, low oil, and if the zerks need any greasing.
These kinds of inspections help prevent component failures that can cascade into larger failures down the road.
Changing teeth and saws
As one of the main inspection and wear points for trimmers and grinders, teeth replacement is a common maintenance item for vegetation management equipment, enough so that most operators can handle the job without the help of a technician, Walser said. This is partly because the wear a grinder or saw experiences can often depend on the kind of tree, i.e. softwood or hardwood.
“Some of them [wear] really quick, and some can last a long time,” Walser explained. “Same with the mulching teeth on the T-Rex. Usually, the operator has the ability to change those out and they have to have the tools to do that on hand, because if they do break a tooth or something fails, the rotor becomes unbalanced and it shakes a lot.”
The same principle goes for Mace’s Vermeer stump grinder, as the teeth tend to be replaced seasonally, he said.
“A good rule of thumb with stump grinders is to replace all the teeth at once, because they wear in a way that's ergonomic to the stump grinder,” Mace stated. “They're set up in such a way that if one tooth starts to wear, it disproportionately wears the tooth behind it, in a lot of ways it’s similar to a chainsaw.”
This means that a worn tooth tends to make the one behind it grab more product and experience more wear.
But at least tooth replacement on a stump grinder doesn’t take any special equipment, with Mace noting that it only requires a torque wrench and a careful eye.
“You do need to torque the bolts down to a very specific pounds per square inch, because if you throw a tooth, it would be pretty detrimental to a person or the machine when the wheel is spinning at 1,000s of rpms,” Mace emphasized.
Technician tasks
While an equipment operator can handle simpler tasks like cleaning or greasing for a trimmer or grinder, there are some duties that are best for a technician to handle, such as internal repair related to electronics and sensors.
“In a lot of our machines, especially in the T-Rex mulcher, we have a lot of safety interlocks in that machine to allow or not allow the rotor to turn,” Walser explained. “In the past, the machines were not as smart as they are today, where we have a lot more electronics on them.”
This can lead to technicians replacing items that roundaboutly impact an operator’s safety, which can cause the equipment not to start, such as a broken door switch. Mace’s stump grinder works similarly, with the grinder able to shut off automatically and generate a fault code for technicians to service.
“If it senses that something is going to affect the life of the stump grinder, it's going to shut it itself off,” Mace said. “If it senses it's out of oil or out of hydraulic fluid, it's just going to idle down.”
Other bigger tasks fit for a technician can include larger oil changes, hydraulic system maintenance, and filter changes.
“In some instances, we have a time where you drain the hydraulic oil, so you need a technician there so they can properly catch it for environmental reasons,” Walser said. Additionally, Walser said that they encourage their customers to take oil samples and have them tested, which can help them know when to replace their oil on time.
“You could take an oil sample, and depending on where you're at, it could be anywhere from $30 to $100 to ensure that your oil is still good, versus the 1,000s of dollars to replace the oil in that machine,” Walser said. “[It] is a large cost savings, especially if you can extend [the machine’s lifespan] by hundreds of hours.”
Technicians might also have a couple mechanical tasks when it comes to vegetation management equipment. For example, the Jarraff tree trimmer may need a technician to service the turntable (sometimes called the swing function) and set the distance between the gear that swings the machine and the gearbox that turns it.
Equipment to keep on hand
For both operators and technicians, there are a couple of tools and pieces of equipment that are helpful to keep on hand. At the most basic level, having a grease gun and hand tools are useful for general maintenance, Walser noted, and Mace said that an electric grease gun is particularly helpful. Additionally, Walser recommended technicians keep certain personal protective equipment on hand, especially when changing teeth.
“When we talk about how sharp it is, we recommend that they have gloves because even the old one might be dull, but still sharp, and the new one is really sharp,” Walser stated.
