After felling a tree, a tree stump grinder is often the most efficient way to grind the stump into mulch. Large stump grinders are powerful machines with hydraulic controls and multi-toothed cutting wheels that spin at high speeds to strip away small pieces of the stump, progressing deeper with each pass. Commonly used in commercial and industrial operations, these stump grinders are also widely available for rent by homeowners. Over the last two decades, injuries resulting from use of this machine have often involved one operator behind the stump grinder controls when another comes in contact with the moving cutter wheel. ESi consultants Dennis B. Brickman, Anne C. Mathias and Julius M. Roberts recently performed a stump grinder accident reconstruction and analysis to better understand what happens and why.
Mr. Brickman recently presented their findings at the 2018 ISOES conference in Pittsburgh, Pennsylvania – a leading international forum for practitioners and researchers involved in the design and analysis of safe human work systems. In their paper, “Stump Grinder Accident Investigation and Design Testing Methodologies,” the authors detail the reconstruction of a 2014 stump grinder accident where a Michigan homeowner sustained a leg injury while operating a rented stump grinder at his home. Their paper included an analysis of accident statistics over the last two decades, stump grinder safety warnings and best practices, machine design safety features, and design testing methodologies.
Based on this analysis, large tree stump grinders are aggressive cutting machines and warrant strict adherence to safety precautions and requirements during operation. Accident statistics show that some design safety features built into these grinders may be less effective when more than one person is present. For example, requiring operator presence at the controls – and therefore away from the cutting wheel – does not prevent injuries when there is another person at the scene. Injuries can still occur as a result of bypassing operator presence controls (OPC), OPC failures, or one person engaging the cutter wheel when another is in the risk area.
Current stump grinder safety standards and industry best practices specify that operators should deenergize the machine, remove the key, and ensure the cutter wheel is at rest before leaving the operator position. Following these requirements, as well as those contained in the manufacturer’s warnings and instructions, can contribute to reducing accidents involving large tree stump grinders. To find out more about the paper and presentation, reach out to Dennis Brickman at firstname.lastname@example.org.
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