A brush hog, often called a rotary cutter, is a heavy-duty mowing attachment designed for land clearing and managing rough terrain. Typically mounted to a tractor’s power take-off (PTO), it uses thick, intentionally dull blades that swing on hinges. Unlike a finish mower, a brush hog uses blunt force to impact and shred dense vegetation. Its robust construction and hinged blades allow it to deflect minor obstructions and handle material that would damage a conventional cutting deck, making it ideal for reclaiming overgrown fields.
Soft Vegetation and Dense Fields
The brush hog excels at clearing high-volume, non-woody organic growth too tall or dense for a typical mower. This includes tall grasses, thick weeds, and overgrown pasture material containing tangled vines and heavy cover crops. The rotary cutter’s design processes this heavy, massed vegetation, allowing it to handle material several feet high without clogging the deck.
The machine’s high-speed rotation shreds herbaceous material into finer pieces, distributing the organic matter back over the soil surface. This action is effective on tough field plants like thistle, goldenrod, briars, and brambles. The sheer volume and height of the soft material, rather than its diameter, dictates the brush hog’s efficiency, allowing for the quick clearing of large, neglected areas.
Woody Growth and Diameter Limits
The rotary cutter’s ability to handle small trees and thick brush is directly linked to the machine’s duty rating and the tractor’s horsepower. Light-duty brush hogs are rated to cut soft woody material up to about 1 inch in diameter. Medium-duty cutters have the structural integrity and power requirements to handle saplings and brush in the 2-inch range.
Heavy-duty models require substantially more PTO horsepower and process material up to 3 inches, and sometimes 4 inches, in diameter. This capacity allows them to clear small softwood trees and dense shrubs like sumac or multiflora rose. The cutting mechanism is a forceful impact that shatters and shreds the woody stem at its base, resulting in a jagged cut that discourages quick regrowth. The type of wood also affects performance; a 2-inch softwood sapling is easier to cut than a 2-inch hardwood sapling.
Material Size and Composition Limits
While a brush hog is engineered for rugged use, it has distinct limitations regarding the size and composition of material it can safely process. Attempting to cut organic material that significantly exceeds the rated diameter risks stalling the tractor or causing severe mechanical failure. A cutter rated for 3-inch material should not be driven over a 5-inch tree trunk, as the excessive force can damage the gearbox, shear the drive pins, or bend the blades.
Inorganic or hard, non-organic materials pose a serious hazard to the equipment and the operator. The cutter is not designed to process debris like large rocks, concrete chunks, metal scrap, or fencing. Striking these objects can cause sudden blade breakage, launching high-velocity shrapnel from beneath the deck. Even smaller, buried items can damage the blade construction or bend the spindle, necessitating costly repairs.