A bush hog or "brush hog" is a type of

rotary mower Rotary may refer to: General * Rotary motion Engineering and technology * Rotary dial, a rotating telephone dial * Rotary engine (disambiguation), multiple types of engines called "rotary" * Rotary latch * Rotary milking shed, a type of milkin ...

. Typically these mowers attach to the back of a

farm tractor A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a Trailer (vehicle), trailer or machinery such as that used in agriculture, mining or construc ...

using the

three-point hitch The three-point hitch (British English: three-point linkage) is a widely used type of hitch for attaching ploughs and other implements to an agricultural or industrial tractor. The three points resemble either a triangle, or the letter A. Three-p ...

and are driven via the

power take-off A power take-off or power takeoff (PTO) is one of several methods for taking power from a power source, such as a running engine, and transmitting it to an application such as an attached implement or separate machine. Most commonly, it is a sp ...

(PTO). It has blades that are not rigidly attached to the drive like a

lawnmower A lawn mower (also known as a mower, grass cutter or lawnmower) is a device utilizing one or more revolving blades (or a reel) to cut a grass surface to an even height. The height of the cut grass may be fixed by the design of the mower, but g ...

blade, but are on hinges so if the blade hits a

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, it bounces backward and inward, and then centrifugal force makes it go outwards again. The rotary blades are not sharpened in the same way as a conventional mower blade. They are usually quite dull so they whack through dense plant growth, whereas a sharp blade often gets stuck or slowed. The blades are very heavy, up to an inch thick, so the centrifugal force pulling out is stronger than the forces of the

vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic character ...

bouncing in. They are made of heat treated

high carbon steel Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, coba ...

that can withstand strikes with hard objects such as

rocks In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's ...

and stones.

Types of brush hog

Two archetypes of this type of mower are the Bush Hog which is made by Bush Hog, Inc. of Selma, Alabama and the Flex-Wing by RhinoAg of

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. The formal name for this type of implement is a rotary cutter or

, although it differs from mowers in that it does not cut with a sharp blade, but rather severs with an intentionally very dull wedge-like blade. Several other manufacturers make these types of mowers including: *Bush-Whacker *DR Power Equipment *Hardee By EVH Manufacturing Co. *King Kutter *Land Pride *RhinoAg *Woods Equipment There are two types of attachment for a rotary mower, either using the

or via a

draw bar A drawbar is a solid coupling between a hauling vehicle and its hauled load. Drawbars are in common use with rail transport, road trailers, both large and small, industrial and recreational, and with agricultural equipment. Agriculture and ...

. The height of the cut on models attached on the three-point hitch is adjusted using the hitch control lever. This adjusts the height of the front of mower. For more radical height adjustment the rear wheel can also be adjusted. Typically the mowers in this category range from mowing widths. A rotary mower that applies chemical while cutting was patented by Tom Burch of Boone, N.C. and was later sold to Diamond Mowers Inc. of Sioux Falls, S.D. under the name Wet Blade

On draw bar models the height of the cut is determined using

hydraulic rams A hydraulic ram, or hydram, is a cyclic water pump powered by hydropower. It takes in water at one " hydraulic head" (pressure) and flow rate, and outputs water at a higher hydraulic head and lower flow rate. The device uses the water hammer e ...

on the mower itself; this requires remote hydraulics on the tractor. These mowers in this category range from mowing width. Draw bar mowers which are able to mow larger widths up to are available. These are multi-spindle and hinged so that the side wings can move over varied terrain. Also these wings can be folded up into a vertical position to reduce width for transport on roadways.

Safety

The blades on a rotary cutter can have top speeds of over . Therefore the

kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its accele ...

enables the blades to cut through saplings and small trees up to several inches/centimetres in diameter. Consequently, these mowers can be very dangerous and contact with the blades would cause severe bodily injury or death. These cutters also pose a thrown object hazard. Objects such as rocks, stones and roadside debris can be thrown in excess of .{{cn, date=March 2020

Sizing

Larger rotary cutters require more powerful tractors to effectively operate. Tractor dealers can recommend the right size brush hog for any of their tractors, or tractor and brush hog sizing charts are available on the Internet. CalculatorsBrush hog mowing calculator
tractordata.com used to estimate the time required to mow different size areas with different size cutters are also available and can be used to help decide which brush hog is the best investment for different situations.

References

Agricultural machinery Lawn care