A tree chipper or wood chipper is a machine used for reducing wood (generally tree limbs or trunks) into smaller wood chips. They are often portable, being mounted on wheels on frames suitable for towing behind a truck or van. Power is generally provided by an internal combustion engine from 3 to 1,000 horsepower. There are also high power chipper models mounted on trucks and powered by a separate engine. These models usually also have a hydraulic winch.

The original chipper design employs a steel disk with blades mounted upon it as the chipping mechanism. This technology dates back to an invention by German Heinrich Wigger, for which he obtained a patent in 1922. In this design, reversible hydraulically powered wheels draw the material from the hopper towards the disk, which is mounted perpendicularly to the incoming material. As the disk is turned by a motor, the blades mounted on the face of the disk cut the material into chips. These are thrown out the chute by flanges on the edges of the disk.


Drum chippers employ mechanisms consisting of a large steel drum powered by a motor. The drum is mounted parallel to the hopper and spins toward the chute. Blades mounted to the outer surface of the drum cut the material into chips and propel the chips into the discharge chute. Commercial-grade drum-style chippers usually have a material diameter capacity of 25 to 60 cm.

Conventionally-fed drum chippers use the drum as the feed mechanism, drawing the material through as it chips it. These are colloquially known as "chuck-and-duck" chippers, due to the immediate speed attained by material dropped into the drum. Chippers of this type have many drawbacks and safety issues. Hydraulically-fed drum chippers have largely replaced conventionally-fed machines. These chippers use a set of hydraulically powered wheels to regulate the rate of feed of material into the chipper drum.

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