Depending on your workload, there’s bound to be an ideal type of wood chipper for your purposes. There are numerous kinds of chippers, built for different tasks and capable of varying workloads. Let’s take a look at the different categories:
Most people simply call them by the broad term, “wood chippers.” They’re the small, tow-able kind you see being used by utility workers around town as they mulch up fallen branches. These are the kinds that can easily attach to your tractor via a 3-point hitch. Brush chippers typically range between approximately 25 to 275 HP, and are classified by their “in-feed throat capacity,” which refers to the inches in diameter of the logs it can mulch.
These chippers use either discs or drums to mulch branches and limbs. Discs are advertised with the number of “knives” fitted on them, which somewhat resemble large single-edge razors. These knives are fitted in notches within the discs (usually 2 or 3 notches), which chip away at branches as they’re fed into the machine. Drums look more like grooved cylinders — they have enormous torque and can make short work of a thick tree limb.
The smaller, more commonly seen brush clippers typically weigh around 1,200 lbs., and have shorter in-feed tables, which is where you would rest a tree limb as it gets fed into the chipper. If you intend on chipping long branches, you’ll want to consider a chipper with a longer in-feed table.
Modern brush chippers include helpful features to remedy jams, by pushing a tree limb out and back in until it “catches” and finally mulches.
It’s important to note that wood chippers are extremely dangerous pieces of equipment. Newer models have numerous emergency shut-off options, including foot and hand bars that can be engaged at any time to shut the chipper off.
Whole Tree Chippers
These chippers look like over-sized versions of the brush chipper, and have been built with the endurance to chip an entire tree from tip to tip, usually up to a full 2′ in diameter. They’re typically of the higher-end of the horsepower range, and are tow-able by tractor or utility vehicle.
These kinds of chippers are far more heavy-duty than brush chippers, featuring conveyor belts that feed material directly into the chipping mechanism, which usually consist of a single serrated drum, or pair of these drums (also known as a “mill”). There are two kinds of horizontal grinders: attachments that can be hauled via a tractor or utility vehicle, and actual self-driven vehicles complete with a cab.
Horizontal grinders usually have top-load access, where an excavator or backhoe may dump bundles of tree waste, planks, branches and limbs directly onto the conveyor. A discharge conveyor on the other end of the grinder points upward at a 45-degree angle, dispensing the mulch into a large pile.