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Safety Alert

Logger Cuts Hand on Chipper Counter-Knife

By Forest Resources Assn.
Date Posted: 12/1/2005


        The owner of a logging business was changing counter-knives on a whole-tree chipper on a cool, pleasant winter morning in the Southeast.

Personal Characteristics

        The 43-year-old owner had been running a chipping operation for five years and had been involved in logging for about 10 years. He had experience working on chippers and logging machinery and was fully trained to handle aspects of logging. He was wearing gloves.

Unsafe Act or Condition

        There was not enough clearance inside the chipper to use an air wrench to loosen the bolts on one of the chipper counter-knives, and the owner did not have a tool on the job that could easily remove the bolts. He decided to loosen a bolt using an allen (hex) wrench with a box-end wrench slid over the allen wrench for added leverage.


        When the bolt suddenly loosened, the wrenches lurched quickly and unexpectedly, and the back of the logger’s hand was forced into the counter-knife.


        The counter-knife cut through the leather glove and partly severed a tendon on the back of his hand between the forefinger and middle finger. He required hospitalization and stitches along with physical therapy.

        The owner was out of work for six weeks. After the six weeks, he returned to his usual duties, operating the loader, and was hoping for an eventual full recovery.


        The owner has since purchased a ratcheting tool that safely and more effectively removes the counter-knife bolts.

        For added safety, consider placing a protective covering, such as a rubber strip or PVC paper (slit lengthwise) over the counter-knife when loosening the bolts. Always wear gloves when working
with chipper knives or counter-knives. In this case the leather glove did not prevent an injury, but it reduced the severity of the injury.

(Source: Forest Resources Assn.)


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