Stump Grinder Maintenance

How to maintain your stump grinders for maximum productivity and profitability.

Stump grinders are available in a variety of configurations. The most popular is the self-propelled type, shown above.
Stump grinders are available in a variety of configurations. The most popular is the self-propelled type, shown above.

If you've ever tried to dig a tree stump out of the ground, you know it's grueling work, nearly impossible to do, unless you have a stump grinder to assist you. And because the work is so tough, a stump grinder really takes a beating. Here's how to maintain your stump grinders for maximum productivity and profitability.

According to Jason Showers, tree care products group sales manager at Morbark, there are four types of stump grinders: handlebar, self-propelled via track or rubber tire, tow-behind and attachment.

"The handlebar style is typically gas powered," says Showers. "This model can either be configured as a manually operated unit, or is also available in a self-propelled configuration. This type of unit is popular with rental yards, DIY customers and customers requiring a small portable unit to access tight or hard-to-reach areas."

The self-propelled track or rubber-tire units can be either gas or diesel powered with a self-propelled drive. "This is the most common grinder on the market with the widest configurations available," says Showers.

Tow-behind stump grinders are normally diesel powered and are towed behind a truck. "This is the oldest stump grinder configuration," Showers says. "They're popular with municipalities doing curbside streetscape work."

Stump grinder attachments are available in a wide variety of configurations. They can be configured as an auxiliary equipment attachment (i.e. skid steer, or carrier mounted), self-contained excavator attachment, or Power Take Off (PTO) models for use on the back of a tractor, attaching to the three-point hitch.

Get your teeth checked regularly

The teeth of a stump grinder take the most abuse, says Todd Roorda, a solutions specialist in the EV segment with Vermeer Manufacturing Co. They should be replaced as wear dictates, and the rate of wear depends on many variables, including the material being cut. "Old wood is dryer, for example, and creates more wear on the teeth," Roorda says. "The operator should always do a pre-cut inspection."

Worn teeth can be sharpened and this should be done whenever the tips get rounded, Roorda says. "After each rental, check to see if the carbide is worn or gone. The softer metal behind it wears a lot quicker and if wear isn't caught early, there's a greater chance of wearing out the pocket or wheel, which just adds expense."

JR Bowling with Rayco agrees that teeth are the number-one wear item on stump grinders. "We encourage every rental company to have an extra set of teeth on the shelf," he says. "Provide fresh teeth with every rental and sharpen the other set in the meantime."

He continues, "Most [rental businesses] can get two or three sharpenings out of a set. The more the teeth get sharpened, the less material comes off, so it pays to do it often."

Bowling adds that teeth need to be sharp and tight. "If they're loose, they could come off, which is a safety hazard and could damage the cutter wheel."

Rental returns

Roorda advises that it's important to power wash a stump grinder once it returns from a rental. This removes dirt from the moving parts so any damage can be easily spotted.

"Stump grinders should be greased at the end of the day," Roorda adds. "If the machine sits outside, the bearings and pivot points collect moisture. You want to get some grease in there to keep the moisture out and prevent premature wear."

Bowling notes that the engine air filter is another important maintenance point on stump grinders. "In a lot of areas, especially in summer, it can get pretty dry and dusty, and a stump grinder kicks up a lot of dust," he says. "It's necessary to do frequent service of the air filter. If the engine fails due to dirt in the engine, it can be a costly repair. Because of the expense, you need to go above the manufacturer recommendations. And don't rely on any [machine] indicators."

He continues, "Check the air filter after every rental, but discourage customers from doing it. They might disturb something."

Bowling also advises rental businesses to maintain a constant oil level. "The oil level is important. It shouldn't be too low, or over filled either. You need to make sure it's accurate," he says, adding, "It's also important to check any safety devices, such as the operator presence system and emergency stop buttons, to make sure they're working properly."

Other common wear areas of a stump grinder are the belts and bearings. "While the stump grinder is a very simple machine in theory, it is important that customers take the time to properly maintain their investment to increase uptime and reduce unwanted down time," Showers says. "Daily maintenance on a stump grinder should include an inspection of the cutting system components, belt and hose inspection and lubrication, as specified in the OEM user manual schedule."