Tree harvesters and processor attachments equipped with hydraulic bar saws cut with great power and speed.
When a chain breaks, if a resulting whipping action projects a chain shot link, the link often has a mass, velocity and resultant energy, in some cases enough to reach an operator in a cab, which has potential to cause damage, harm or severe injury.
This may be complicated by the remote nature of forestry operations.
“Even very experienced operators can be exposed to chain shot risk. Manufacturers strive to design out hazards but a design that completely eliminates the chain shot hazard is a tall order. So always follow safety best practices,” says Nathan Burton, technical & safety services manager of the Association of Equipment Manufacturers (AEM).
Follow these tips from AEM’s Forestry Equipment Council to help advance chain shot safety:
· Use correct machine settings
o Know and follow recommended settings of machine and attachment manufacturer, and read operator manuals for safe operating guidance.
o This includes hydraulic settings. Out of spec pressures and speed adds considerable strain, which can contribute to the risk of chain failure.
· Check every chain before and after sharpening
o Always use high quality chain recommended for the attachment, and inspect each chain before mounting. Look for link pin wear, signs of strain, and accidental damage during sharpening. Discard questionable chains.
· Avoid habits that risk chain damage
o Keep the saw above ground.
o Remove chains at the first sign they need sharpening. Dull chains place more stress on the links.
o Equip the harvester/processor attachment with a “chain catcher” and “energy absorbing shot guard” – should meet requirements of ISO 11837:2011 “Machinery for forestry - Saw chain shot guarding systems - Test method and performance criteria.”
o Inspect the shot guard and chain catcher with every visit to the attachment. Replace or repair as needed.
· Know and respect the “shot cone,” that is, the likely path of chain shot travel. This follows the plane of the bar in both directions so all in the shot cone are at risk.
o In use, orient the attachment so the “shot cone” is pointed away from you and other machine operators, co-workers, or bystanders. Check that no persons in the shot cone area are masked from your sight.
o Know where the chain shot zone is relative to the bar and chain; don’t align to look directly down the bar during cuts!
· Care for the cab windows
o Cab windows that can be exposed to the “shot cone” should meet the appropriate requirements to serve as effective guards.
o Don’t make unauthorized modifications to the glazing or the mount, and follow appropriate maintenance procedures. Some cleaners are not suitable for many window materials.
AEM and safety awareness
AEM is the North American-based international trade association representing the off-road equipment manufacturing industry. AEM supports safety awareness year-round by offering an extensive array of safety products, including operator safety manuals, for major equipment types covering forestry, aerial, agricultural, compact/portable, earthmoving, lifting, road paving and utility excavation applications.
AEM’s Forestry Equipment Council was established in 1975 as a manufacturers’ forum to discuss and work cooperatively on issues affecting forestry and forest harvest operations, including operator safety. Forestry-specific products include log skidders, tracked and wheeled fellers, tracked and wheeled harvesters, log forwarders, and knuckleboom loaders. Visit www.aem.org for more information