How Does a Chipper-Shredder Work?

How They Work

• Chipper-shredders are powered either by an on-board gasoline engine or by a shaft connected to the power take-off of a tractor or truck that is powered by the vehicle’s engine. The engine drives a set of sharp steel blades attached to a rotating drum that slices branches into small chips before discharging them from the machine. The engine also drives a shredder with a set of hinged steel blades called flails that reduce leaves to shreds before discharging them. These machines reduce yard waste volume by up to 90 percent.

Sizes

• Chipper-shredders are designed to handle leaves, twigs and branches up to 3 inches in diameter. If you have branches larger than 3 inches, you need to move up to a more-powerful machine that only does chipping. These pure chippers mount big engines, up to 50 hp, that can handle branches that are more than 6 inches in diameter. At the opposite end are pure shredders, designed for light use to handle leaves and twigs only. These small units may be gas- or electric-powered.

Clutch or Direct

• Smaller and less-expensive chipper-shredders typically are direct-drive units. This means that the blades are moving whenever the engine is running. Large machines may have a clutch that disengages the blades from the engine when the machine is not actually chopping up vegetation. A clutch takes the load off the engine, allowing easier starting. Most chipper-shredder models have a large loading hopper for leaves, a small loading chute for branches, and a discharge chute for the chopped-up material.

Safety Compliance

• Chipper-shredders should have stickers proclaiming compliance with the safety standards of the Outdoor Power Equipment Institute and the American National Standards Institute. Before using for the first time, read the machine’s operating manual. Make sure all guards and shields are in place. Wear work gloves when feeding branches into the machine in case the machine pulls the branch out of your hand. When you’re feeding leaves into the hopper, always use the tamper that came with the unit. Never use your bare hands to push leaves down into a running machine. Wear eye protection and avoid loose, baggy clothing.