Wood chippers are an amalgamation of parts, including a hopper, a collar, a chipper, and usually, a collection bin. Typically powered by a combustion engine (although many electric versions exist), they range in horsepower, depending on size and type. How wood chippers work is an interesting mix of processes.
All wood chippers contain the same basic pieces. An engine, whether electric or gas, provides power to a gearbox containing v-belts and pulleys, which lead to knives or rollers that chop, slice or mulch or grind, depending on the size and nature of the wood it receives. Most feature separate chutes for the resulting product: one for wood chips and one for mulch. The larger the machine, the bigger the branches it can handle.
Here are the different processing mechanisms:
Drum Chippers: Drum chippers feature a large, motor-run drum inside the machine. Drums are able to pull in material before cutting it then directing it to the appropriate chute. Drum-style chippers work quickly, but run loud and require careful operation. Users must feed carefully, so as to avoid blockages and jams.
Disk chippers: Disk chippers contain a steel disk the edges of which are cut into blades. Wheels (generally hydraulic) move the material to be chipped toward the blades. Disks come in a wide array of sizes and horsepower.
High Torque Rollers: Torque rollers are a common feature of electric chippers. Quieter than gas powered chippers, electric models are generally preferred by homeowners associations and considerate neighbors. The rollers work by grinding the material rather than chopping.
Whole Tree Processors or Recyclers can cut branches or trunks up to six feet wide, while Tub Grinders process trunks or branches up to eight feet wide. They process wood through pulverization rather than cutting, chopping, or grinding. These are used by professional arborists, in clearing or pruning applications.