When The Chips Are Down: Chippers/Shredders

Manufacturers of chippers and shredders hope to capitalize on this environmental bent, and encourage lawn and landscape contractors to look at the myriad benefits to be enjoyed by adding one of their tools to their equipment lineup.

Indeed, chipper and shredder manufacturers visited by Lawn & Landscape at the International Lawn, Garden & Power Equipment Expo in Louisville in July talked about increased interest from contractors.

"Contractors need to be able to offer more services because they’re banging their heads against the wall trying to get more mowing business," explained Ross Johnson, marketing manager, Crary Bear Cat Co., West Fargo, N.D. "Having a chipper or shredder boosts their business."

KNOW THY WORK. All of the manufacturers agree the first step in purchasing one of these machines is anticipating exactly how it will be used.

Chipper units are designed to turn tree limbs and branches into small wood chips, but that doesn’t mean every machine can handle the same branches. "Each manufacturer has a maximum rated capacity for its machine," explained Mark Rau, assistant sales manager for brush chippers, Morbark E-Z Beever Co., Winn, Mich. "Too many people expect the machines to handle that size material without problems or without having to stop or reverse the feed roller periodically. We use the analogy that a car’s speedometer may read 100 miles per hour, but that doesn’t mean it can run that fast all day every day."

"Contractors should remember the ‘rule of thirds,'" recommended Rau. "If they intend to work mostly with 6-inch diameter branches, then they should look for a machine with a 9-inch capacity."

A chipper/shredder differs from a chipper in the way its name would suggest - it offers chipping and shredding capabilities.

"First, a chipper/shredder chips the wood," Rau noted. "Then, as an integral part of the cutting mechanism, it has a hammermill inside, and the wood is pulverized into a mulch."

"Chipper/shredders have two openings - one feeds branches into the chipper, the other feeds materials into the shredder," said Tim Crowley, national sales manager, The Patriot Company, Milwaukee, Wis. "This is important to contractors dealing with branches along with grass and leaves."

This versatility suits many contractors’ needs, but there can be tradeoffs in terms of productivity capabilities compared to independent chippers. "To hammer and pulverize material takes more horsepower, so users may be limited in terms of their chipping capacity," Rau added.

Mark Couturier, president, Chip-It Industries Inc., Bay City, Mich., also warned that having a chipper/shredder could lead contractors to misuse the machine. "Some people think that whatever doesn’t belong in the chipper must go in the shredder," he said. "That’s not always true, though, and that can cause some real damage to the machine." This includes non-wood materials or chunks of wood which are too large for the shredder.

CONSTRUCTION IS THE KEY. "These are the most abused machines in the industry," asserted Johnson. "Mowers get beat up when they hit a branch once in a while, but that’s all chippers and shredders deal with, so there should be a real emphasis on quality construction when buying these machines."

"Contractors should compare the gauge of steel used in different machines, especially in high wear areas such as the feed and discharge chutes," recommended Couturier. "It isn’t the wood and the chipping that wears out the machines as much as it is the vibrating and high rpm levels, which can fatigue the sheet metal."

"Some manufacturers may use bolt-together construction, but we recommend welded construction," added Johnson. "It’s also important to see how much support is offered the machine in areas of extra stress."

"Every chipper has an impact point where the wood is laying when the knife makes contact. That area takes a real beating, and it has to have steel support to absorb the shock," agreed Rau. "Light gauge steel in these areas won’t last."

Of course, the construction of the cutting mechanism also warrants attention. "We use tri-plate rotors for extra rigidity in our chipper/shredders," noted Crowley. "That way the blade won’t deflect when the plate hits the wood."

"We also use two 3-inch cutting knives on each unit, and they’re made of high carbon, hardened tool steel for increased durability," continued Crowley.

"Contractors should also examine the cutting disc, shaft and bearings assembly to make sure they are of adequate size," added Rau.

"Some manufacturers use a centrifugal clutch to drive the cutting system, and that clutch lining can wear out," claimed Couturier. "We use direct drive through belts. People think that’s hard on the engine when you start it up, but we’ve had our system approved for use by the engine manufacturers."

NEW & IMPROVED. While the manufacturers agree most chippers and chipper/shredders on the market are quality machines, they continue to work to improve their products.

"We’re seeing a growth in the popularity of hydraulically-fed units," observed Couturier. "They can handle brushier types of material because the feed wheel compacts it before it gets to the cutting blade, and that requires less stopping of the machine for the operator to prune.

"Hydraulic units are also thought of as being safer to work with because they don’t pull the material in as fast, they’re not as noisy as drum chippers and the feed wheel is further from the cutting disc," Couturier continued. "The downside is that hydraulic machines only feed material at 100 feet to 120 feet per minute, which is considerably slower than the drum chippers, and the hydraulic system requires additional maintenance and costs more."

"Electronic feed sensors are becoming very popular," Johnson said. "They sense the speed of the rotor disc, and if the disc starts to get bogged down the sensor automatically shuts off the fluid going to the hydraulic motor. This stops the material from feeding into the machine and allows the engine to build the disc rpms back to the appropriate level. Then the sensor automatically restarts the material feed."

PASS THE CHIPS, PLEASE. Again, the driving force behind using these tools is reducing the amount of yard waste which has to be dumped in landfills.

"We should see more reuse of wood chips around trees and as attractive ground covers than we see right now," noted Johnson. "But even if contractors don’t leave the materials on the property, the chipper lets them haul much more material in the truck or trailer than they would otherwise, and this saves a great deal of time and money."

When it comes to using chippers/shredders for producing mulch, contractors needs to pay attention to what materials are fed into the machine, though. "If branches are mixed in with grass and leaves to form compost or mulch, the wood chips will absorb the nitrogen produced in the decomposition of the shredded materials," warned Crowley. "That means the food value of the mulch as a nitrogen fertilizer for the soil is wasted. Keeping wood chips separate when creating the mulch eliminates the problem."