Handheld Trimmers and Brush Cutters

Small Farm and Gardening Safety and Health Series
Agriculture and Natural Resources
S. Dee Jepsen, Associate Professor and State Safety Leader, Agricultural Safety and Health, Food, Agricultural and Biological Engineering
Jeffery Suchy, Graduate Student and Lecturer, Food, Agricultural and Biological Engineering

Handheld trimmers and brush cutters are capable of performing numerous tasks on small farms and gardens. While they are usually used for completing grass-trimming operations, many are designed to incorporate attachments such as brush-cutting blades, cultivators and edgers. They vary in size from small, handheld models to larger units with shoulder straps and handlebar controls.

Although relatively small, these machines are powerful, and contact from rotating cutters and flying debris can cause serious injury including cuts and lacerations. They pose additional risks to the operator and bystanders due to their tendency to throw objects from their spinning action. By following basic safety precautions, they can be operated safely, and the chance of injury can be greatly reduced.

Safe Operation

Trimmer and brush-cutter safety relies on the operator being aware of the proper use and inherent dangers associated with the task being performed. Always read and follow the manufacturer provided operator’s manual before using the equipment and any attachments. Although many units appear similar, there may be safety and operation features unique to each brand or manufacturer. If the operator’s manual cannot be found, obtain a replacement by contacting the equipment manufacturer or a local dealer.
Follow these general precautions before fueling and starting the equipment:
• Become familiar with proper equipment operation including starting, stopping and making adjustments.
• Inspect the unit and attachments for signs of wear and damage.
• Make sure shafts and connections are properly tensioned or tightened.
• Verify that the shields and deflector guards are in place, and that the safety features are not overridden.
• Refuel the engine only when it is cool.
• Do not smoke when working around fuel sources.
• Place the unit on the ground before starting it.
• Do not operate equipment in a closed building, as poisonous gases (carbon monoxide) can build up quickly.
Follow these general precautions when operating the equipment:
• Operate the unit only on stable ground, and maintain good balance and secure footing to avoid potential slips and falls.
• Do not operate the unit without the proper shield deflector in place.
• Inspect the area where the equipment will be used, and remove all visible stones, sticks, wires or other debris.
• Do not cut near hard objects when using rigid blades.
• Keep the hands and feet away from moving parts and cutting blades.
• Maintain a firm grip on the handles, and work slowly to minimize kickout and the risk of hitting hidden objects.
• Use the attachments only as they were designed to be operated.
• Be aware of bystanders in the event of thrown objects. Allow at least a 50 feet of safe distance.
• Do not operate the equipment when fatigued or under the influence of drugs or alcohol.
• Operate the equipment only with adequate visibility and light.

Safe Operation of String Trimmer Owner’s Manual

Inspection and Maintenance

Keep the equipment and all attachments in good repair. Use the maintenance schedule provided in the owner’s manual, which is the best source of information regarding equipment maintenance. Proper maintenance will increase the life of the equipment and decrease the likelihood of safety risks due to equipment malfunction. Well-maintained equipment will result in less strain on the equipment and operator, and will allow tasks to be performed more efficiently.
Always shut off the engine and disconnect the spark plug wire before performing maintenance or changing attachments. Follow these common maintenance and inspection guidelines:
• Review the operator’s manual for recommended service.
• Maintain proper oil levels and lubrication of moving parts.
• Maintain the cutting edges on the blades (not required on string lines).
• Replace the brush-cutter blades when they are damaged or excessively dull.
• Inspect, adjust or replace all deflector guards and safety features.
• Drain the fuel tank in a safe area and run the engine on idle until it stops, before storing the equipment for extended periods.

Personal Protective Equipment

Always use personal protective equipment (PPE) when operating a string trimmer or a brush cutter. Consider the following PPE recommendations:
• Wear safety glasses with side shields or goggles to protect the face and eyes from flying debris when using the cutting attachments. Also wear a face shield or screen over safety glasses to provide additional protection to the face and eyes from flying debris.
• Wear ear protection to preserve hearing and protect the ears from the high level of noise produced by the engine.
• Wear leather gloves to protect the hands from cuts, splinters, abrasions and contact with sharp cutting edges and flying debris.
• Wear sturdy leather work boots or hard-soled shoes to protect the ankles and feet from the rotating cutter head and flying debris. Steel-toed boots help provide additional protection.
• Wear pants and a snug-fitting long-sleeved shirt to protect the skin from flying debris and cuttings.


• Stihl USA. Product Safety Manuals: Trimmer and Brushcutter. 2009. stihlusa.com/manuals/safety-manuals.

Reviewer: Kent McGuire, CFAES Safety and Health Coordinator, Food, Agricultural and Biological Engineering


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