Chain Shot Safety Information Chain shot can cause saw chain parts to be thrown in many directions along the
cutting plane of the guide bar. The “Shot Cone Zone” reflects where saw chain pieces usuall- ly travel in the event of a broken/shot chain (Figure 2).
WARNING: There is risk of serious injury or death to the machine operator, ground personnel and bwystanders from chain shot. Chain shot occurs when a piece or pieces of cutting chain from the end of a broken saw chain in mechanized timber harvesting or processing is ejected at a high velocity. Chain shot typically originates near the drive end of the cutting system but can also originate from the guide bar tip area. Saw chain pieces usually travel in the cutting plane of the guide bar, but can deviate to either side. Do not use saw chain that: • Has broken twice. • Is severely damaged. • Has excessive saw chain stretch. • Has broken or cracked components. • Has loose rivet joints—if you can rotate the rivets with your fingers, they are too loose. Guards & Shields: Because of the high speeds, high stress, heavy loads, wear factors, and varying levels of repair and maintenance given to saw chain-based mechanized wood harvesters/processors, there is a possibility that saw chain or saw chain pieces can be thrown from the machine at high speed and velocity. Machine operators, ground personnel, and bystanders are exposed to a risk of serious injury or death. Equipment should be equipped with appropriate guards, shields, and window enclosures. Care should be taken to minimize the exposure of the machine operator, ground personnel, and bystanders to the cutting plane of the guide bar. Bystanders and ground personnel should be kept at least 300 feet way. Chain Shot Guard: A chain shot guard is a piece of material mounted behind the drive sprocket. This guard performs two functions: • Absorbs the energy of a broken saw chain coming into contact with the saw box, and is designed to prevent saw chain parts from breaking off and being ejected. • Acts as an extension of the saw box, designed to reduce the opportunity for thrown saw chain or saw chain parts to escape the saw box (Figure 1). Operational Recommendations : • Never engage in a cut with ground personnel or bystanders in the shot cone zone. • Always engage in a cut as close to the ground as possible. • Always keep bar and chain pointed away from the cab and operator.
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Harvester Chains and Guide Bars
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