Section 7
Kickback
21
22
23
24
LOW KICKBACK SAW CHAIN
The rakers (depth gauges) (Fig. 24) ahead of each cutter can minimize the force of a kickback reaction by preventing the cutters from digging in too deeply at the kickback zone. Only use replacement chain that is equivalent to original chain or has been certified as low kickback chain per ANSI B175.1 for your saw.
Low kickback saw chain is chain that has met the kickback performance requirements of ANSI B175.1 - 1991 (American National Standard for Power Tools -
PRECAUTIONS AGAINST KICKBACK
Kickback is a dangerous reaction that can lead to serious injury. Do not rely only on the safety devices provided with your saw. As a chain saw user, you must take special safety precautions to help keep your cutting jobs free from accident or injury.
KICKBACK WARNINGS
Refer to Figures 21, 22, 23.
KICKBACK occurs when the moving chain contacts an object at the upper portion of the tip of the guide bar or when the wood closes in and pinches the saw chain in the cut. Contact at the upper portion of the tip of the guide bar can cause the chain to dig into the object and stop the chain for an instant. The result is a lightning fast, reverse reaction which kicks the guide bar up and back toward the operator. If the saw chain is pinched along the top of the guide bar, the guide bar can be driven rapidly back toward the operator. Either of these reactions can cause loss of saw control which can result in serious injury.
Do not rely exclusively upon the safety devices built into your saw. As a chain saw user, you should take several steps to keep your cutting jobs free from accident or injury.
•With a basic understanding of kickback, you can reduce or eliminate the element of surprise. Sudden surprise contributes to accidents.
•Keep a good firm grip on the saw with both hands when the engine is running. Place your right hand on the rear handle and the left hand on the front handle with your thumbs and fingers encircling the chain saw handles. A firm grip together with a stiff left arm will help you reduce kickback and maintain control of the saw.
•Make sure that the area in which you are cutting is free from obstructions. Do not let the nose of the guide bar contact a log, branch, fence, or any other obstruction that could be hit while you are operating the saw.
•Always cut with the engine running at full speed. Fully squeeze the throttle trigger and maintain a steady cutting speed.
•Follow the sharpening and maintenance instructions for the saw chain.
•Use only the replacement guide bars and low kickback chains specified for your saw.
GUIDE BARS
Generally, guide bars with small radius tips have somewhat lower kickback potentials.
The manufacturer’s gasoline saws meet the kickback- reduction requirements of ANSI B175.1 without requiring small radius tip bars.
14
