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The Chainshot Phenomenon
Chains on saws can travel 15,000 revolutions per minute (rpm). When a saw chain breaks, it can scatter linkages into the surrounding area at high speeds. This is known as Chainshot, which commonly moves along the plane of the saw, and can cause a hazard to the operator if the saw is aligned with the cab.
November 8, 2011 By Laura Maguire – BC Forest Safety Council
There have been a number of investigated chain shot incidents in B.C. and internationally in the forest industry. Swedish researchers estimate that a chain shot might occur in 1 in every 50 chain breaks
(Hallonborg 2002).
In B.C., a harvester operator sustained severe abdominal injuries when he was struck by a chain link that had passed through a ½” polycarbonate cab window.
Another worker was using a manual chain saw to cut a dead stump when the chain broke. The broken linkages flew through the air and struck another worker about 35′ away. The chain piece removed in life saving surgery had caused injuries similar to being shot by a bullet.
In addition, workers have reported near misses after nearly being struck by pieces of chain linkages released from equipment being operated up to
300 ft away.
Chainshot can occur when chains are worn, damaged, repaired with used linkages or operated at speeds beyond the manufacturers recommendations. Chainshot can happen on processing equipment or a manual saw. A chain breaks for a number of reasons including:
- Improper tension – chain too loose
- Improper chain maintenance or
- repair (hammered rivets)
- Damaged sprocket, bar and/or chain
- Improper bar and chain lubrication
- Defective chain
- Excessive chain speed. Keep in mind that many chains fail at the instant they are damaged so chain shot cannot be totally avoided.
- There are a number of ways to protect yourself from being injured by chain shot:
- Follow Manufacturers
- Guidelines For Use
- Installing proper guarding
- Positioning & Training
- Purchasing Decisions
For more detailed information on preventing chainshot visit the BC Forest Safety Council at www.bcforestsafe.org or contact Laura Maguire at Maguire@bcforestsafe.org.
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