Brush Cutter Working Principle and Precautions

brush cutter

A brush cutter, also referred to as a grass trimmer, grass cutting machine, or lawn mowing equipment, is a commonly employed tool in households for maintaining lawns. Comprising a gasoline-powered engine, a transmission rod, and a cutting disc, the brush cutter is designed for single-person operation. Its operational principle involves utilizing the power of the gasoline engine to drive the brush cutter's high-speed rotation through the transmission system. This synchronous rotation of the cutting disc allows for the efficient cutting of weeds, employing a generated cutting force.

The brush cutter can be equipped with either a grass rope or a three-tooth blade. The selection of the grass rope's length depends on the spacing between orchard plants and the height of the weeds. Choosing between the grass rope and the three-tooth blade should be influenced by the quantity and thickness of the grass. Regular cleaning and maintenance of the brush cutter are crucial during usage. In unclear situations on damp grasslands, it is advisable to minimize the use of the brush cutter. When operating, grip the handlebars with both hands and maintain a certain degree of inclination.


Be thoroughly familiar with the controls and proper use of the unit. Know how to stop the unit and shut off the engine. Know how to unhook a hamessed unit quickly. Never allow anyone to use the unit without proper instruction. Be sure the operator wears the foot, leg, eye, face and hearing protection. Do not rely on the debris shield on the unit to protect your eyes from ricocheting or thrown objects. Keep the area clear of bystanders, children and pets. Never allow children to operate or play with the unit. Do not allow anyone to enter the operating danger zone with you. The danger zone is an area 15 meters in radius (about 16 paces) or 50 feet.

Insist that persons in the risk zone beyond the danger zone wear eye protection from thrown objects. If the unit must be used where there are unprotected people, operate at a low throttle speed to reduce the risk of thrown objects. Move the stop switch to "stop" position when the engine idles, insure it reliable before cutting. Only may continue to operate the unit when stop switch is in good condition. Routines for checking that the cutting attachment stops turning when the engine idles.


Line head rotates in a clockwise direction.The cut-off knife will be on the
right side of the debris shield.For nearly all cutting, it is good to tilt the line head so that contact is made on the part of the line circle where the line is moving away from you and the debris shield.This results in the debris being thrown away from you.

TRIMMING:This is feeding the trimmer carefully into the material you wish to cut. Tilt the head slowly to direct debris away from you. If cutting up to a barrier such as fence, Approach from an angle where any debris ricocheting off the barrier will fly away from you. Move the line head slowly until the grass is cut right up the barrier, but do not jam(overfeed )the line into the barrier If trimming up to a wire mesh or chain linked fence be careful to feed only up to wire. If you go to far the line will snap off around the wire. Trimming can be done to cut through weed stems one at a time. Place the trimmer line head near the bottom of the weed-never high up which could cause the weed to chatter and catch the line. Rather than cut the weed right through, just use the very end of the line to wear through the stem slowly.

SCALPING AND ENGING: Both of these are done with the line head tilted at a steep angle Scalping is removing top growth leaving the earth bear.Edging is trimming the grass back where it has spread over a sidewalk or drive way. During both edging and scalping, hold the unit a steep angle and in a position where the dibris, and any dislodging dirt and stones, will not come back towards you even if it ricochets off the hard surface. Although the picture shows how to edge and scalp every oprator must find for himself the angles which suits his body size and cutting situation.


There are many different types of blades, however the two most commonly used are the following. Brush blade is used for cutting brush and weeds up to 3/4" in diameter. Only 255mm 3-blade can be used in this type of brush cutter. SAWBLADE is used for cutting growth from 3/4" to 3" in diameter.
SCYTHING WEEDS. This is cutting by swinging the blade in a level arc. It can quickly clear areas of field grass and weeds. Scything should not be used to cut large, tough weeds or woody growths.

Scything can be done in both directions, or just in one way which results in the debris being thrown away from you. That is using the side of the blade that it is rotating away from you. Tilt down the blade slightly on this same side .You will be hit by some debris if you scythe in both directions. SAWING This must be done with a saw blade when the weeds are too thick and strong for scything. If kickback occurs, the blade may be dull, or the material so thick and hard that you should use a saw blade instead of the brush blade. Growth up to 3-inches in diameter, which is too thick for scything, may be cut by sawing. Sawing requires judgement on your part whether to cut on the side where the blade pulls away from you but throws back the debris ,or on the side where the debris is thrown away from you but the reaction is push which could become a kick out. Always cut on the side of the tree which will cause the tree to fall away from the unit. A kick out or bind may result if the tree falls toward the unit and pinches the blade.
Do not force the blade to cut. Do not change the angle of cut after into the wood. Avoid using any pressure or leverage which could cause the blade to bind or crack.

How to protect yourself when using a gasoline brush cutter

Proper safety precautions must be observed. Like all power equipment this unit must be handled carefully. Do not expose yourself or others to danger follow these general rules.
Always wear safety goggles for eye protection. Dress properly, do not wear loose clothing or jewelry that could become caught in moving parts of the unit. Safe, sturdy, nonskid footwear should always be worn. Long hair should be tied back. It is recommended that legs and feet be covered to protect from flying debris during operation.

Inspect the entire machine for loose parts (nuts, bolts, screws, etc.) and any damage. Repair or replace as necessary before using the machine.

DO NOT USE any attachment with this power head other than the ones recommended by our company. Serious injury to the operator or bystanders could result as well as damage to the machine.

Keep the handles free from oil and fuel.

  • Always use proper handles and shoulder strap when cutting.
  • Do not smoke while mixing fuel or filling tank.
  • Do not mix fuel in an enclosed room or near open flames. Assure adequate ventilation.
  • Always mix and store the fuel in a properly marked container that is approved by local codes and ordinances for such usage.
  • Never remove the fuel tank cap while the engine is running
  • Never start or run the engage inside a closed room or building. Fumes from the exhaust contain dangerous carbon monoxide.
  • Never attempt to make engine adjustments while the unit is running and strapped to the operator. Always make engine adjustments with the unit resting on a flat, clear surface.


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