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.
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.
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.
Safe Operating Practices:
- Read the operators manual and obtain training on the proper and safe use of the wood chipper prior to first use of the chipper.
- All safety devices and controls, such as emergency shut-off devices, must be tested and confirmed to be in proper working order before the chipper is used.
- Inspect the wood chipper each time before use. Check for defects such as broken or missing hood latches and pins or cracked and worn hinges.
a) Replace any damaged or missing machine parts before use.
- Before starting the wood chipper, make sure that the hood that covers the chipper knives is completely closed and latched.
- Always set-up warning devices such as barricades, cones, flagmen, etc. prior to starting up the chipper to protect motorists and pedestrians.
- When you are ready to begin putting materials into the wood chipper, run it at the lowest possible speed.
a) Listen for any noise that might indicate broken or loose parts.
b) If an unusual noise is discovered, DO NOT use the wood chipper.
c) Have a professional check out and/or repair the wood chipper as necessary.
- Never break the plane of the hopper with your hands while it is running.
- Always remove the ignition key to the chipper when it is unattended.
- Always feed the chipper from the curb side of the street (when parked in the street).
a) Otherwise, feed the chipper from the side that the emergency shut-off is located.
- Always feed tree limbs and brush butt-end first into the hopper of the chipper.
- Move away from the wood chipper once it has grabbed the material intended for chipping.
- Lay the shorter materials on top of the longer materials or use a long branch to push the shorter material through the in-feed hopper.
- Never place hands or feet into the feed chute.
- Always be aware of the direction the discharge chute is pointed.
- Never put rakings in that may contain rocks, glass, or objects that could shoot out.
- Load leaves and small twigs directly into the wood chipper truck, not into the in-feed hopper.
- Always be aware of your surroundings (people, cars, etc.)
- Keep the area around the wood chipper clear of any tripping hazards.
- When operating a disc chipper, always feed the brush from the right side while turning your body away (disc chipper swings branches to the left).
- When operating a rotary drum chipper, always hold the brush end of a branch higher than the trunk.
- Always make sure that all internal machine parts have come to a complete stop before opening the hood that is covering the chipper disc or drum of the wood chipper.
A wood chipper relies on a powerful motor or engine that creates the incredible torque needed for turning a rotating drum with attached chipper knives. The combination of speed and torque allows commercial chippers to pull in branches at 20 inches per second. As an operator manually pushes brush and tree limbs into a hopper, the feed mechanism and chipper knives grab anything within reach. “Anything” may be tree limbs and brush…or loose jewelry, rope, an arm, fingers, or long hair.
IGNORING SAFETY RULES…CAN PROVE TO BE FATAL!!
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