GENERAL SAFETY, CONTINUED
What is chain shot?
Chain shot is the high velocity separation and ejection of a piece or pieces of cutting chain from the
end of a broken chain in mechanized timber harvesting. Chain shot exposes both machine operators
and bystanders to a risk of serious injury or death. Chain shot typically occurs near the drive end of
the cutting system but can also come from the bar tip area.
Industry research indicates an average of 1 in 50 broken chains had parts missing that may have
been the result of a chain shot event.
How does chain shot occur?
A chain shot consists of two breaks in a chain.
First, the loop of chain breaks and forms two ends. One end moves past the drive sprocket or bar
nose and is rapidly accelerated due to a whip-like motion of the chain end.
The “whip action” causes the second break releasing small parts at supersonic speed.
Chain shot can cause chain parts to be thrown in many directions, especially those along the
plane of the saw bar.
What does a typical chain shot piece look like?
The most dangerous chain shot parts consist of one to four parts as shown:
How can operators reduce the risk of chain shot?
•
Operators and bystanders must never be in the plane of the bar when the chain is in motion on the
bar.
• Appropriate windshield material must be installed.
• Chain speed must be 8000 ft/min (40m/s) or less for .404 pitch Oregon® Harvester chain and
7000 ft/min (35m/s) or less for 3/4 pitch Oregon® Harvester chain.
• A chain shot guard should be installed near the drive sprocket.
• Chains should be inspected frequently and damaged or cracked chains removed from service.
• Always use new Oregon® parts when repairing Oregon® chains.
• Industry groups recommend that chains should be discarded after the second break.
• Remove all dull and/or worn chains from service.
• Always sharpen Oregon® chains to Oregon® factory specifications.
• Maintain proper bar and chain lubrication.
• Maintain proper chain tension.
www.HalversonWoodProducts.com
218-587-2065
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