Mobile wood chippers chop up branches and trunk pieces from tree trimming operations. Workers feed materials through a hopper where the materials are grabbed by a feed mechanism. The materials then pass under rotating chipper knives moving at rates of 1,000 and 2,000 rpm until the tiny pieces are discharged out of the machine. Wood chippers can cause serious or fatal injuries and amputations, so use them with extreme caution and attention to safe work practices.

When operating a chipper, wear close-fitting clothing, cuff-less gloves, cuff-less trousers, and safety boots with non-skid soles. Tie back your hair, take off jewelry, and keep your clothing tucked in. Keep your hands and feet outside the hopper at all times. Know what your coworkers are doing and where they are—working with a buddy ensures that help is nearby if an emergency occurs.

Two-thirds of wood chipper-related fatalities occur when workers get caught and crushed by the chipper feed mechanism and/or get pulled into the cutting knives. You could be seriously injured or killed if you fall into the chipper hopper, get entangled in tree branches, or try to push short branches and debris into the hopper. Clearing jams while the machine is still operating or slowing down can pull you into the cutting knives.

Keep the work area around the chipper clear and free from tripping hazards to avoid falls into the hopper. Rake up small debris like twigs and leaves and place them directly into the trailer or a bag for disposal. Follow the chipper manufacturer’s recommendations for the safest position to stand when feeding limbs into the hopper. Feed the trunk or “butt end” of branches into the hopper first. Always lay short branches on top of longer branches, or use a long branch to push materials into the hopper. Never reach into the feed area to push small debris into the hopper. Once the feed mechanism has grabbed the materials, let go and allow the feed mechanism to draw the materials into the cutting knives.

The remaining one-third of chipper fatalities occur when workers get struck by chipper hood guards, which can fly off forcefully if they are opened or closed while the chipper knives are rotating. Before use, inspect the chipper hood for missing pins or cracked, worn hinges. Ensure the hood is properly latched closed and completely covers the knives.  Start the chipper at the lowest speed and listen for sounds of loose or broken parts. The knives should come to a complete stop before opening the chipper hood.

Get training on safe work procedures based on chipper manufacturer recommendations. Know how to use the safety devices and controls, especially the emergency shutoff switch. Learn where the caught/crush points on the machine are, where to stand, and where to keep your hands and feet during operation. Learn how to open and close the hood, clear jams, and feed branches. Keep the chipper well maintained. Perform safety checks before each use to ensure safety devices work properly. Do not allow workers less than 18 years of age to operate a chipper.

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The above evaluations and/or recommendations are for general guidance only and should not be relied upon for medical advice or legal compliance purposes. They are based solely on the information provided to us and relate only to those conditions specifically discussed. We do not make any warranty, expressed or implied, that your workplace is safe or healthful or that it complies with all laws, regulations or standards.

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