Oregon Maintenance and Safety Manual, MMANUAL-EN AB

Guide Bar Troubleshooting

7. Spread rails. Cause: (1) Saw chain was struck

broadside by tree, log, or branch stub. (2) Saw chain was pushed sideways, forcing drive links to pry guide bar rails apart. Symptoms: Guide bar will not enter log during cut or cannot make complete cut. Remedy: (1) Hammer rails together with a drive link in groove as spacer. Adjust saw return to allow guide bar to go farther into saw box. Sharpen delimbing knives. Avoid moving tree/log when guide bar and saw chain are out of saw box. (2) Reduce guide bar feed speed. 8. Rail on one side worn low. Cause: Damaged or dull cutters on one side, or saw chain leaning over in a worn groove, or using .063" saw chain in .080" guide bar. Most often one short rail is caused by cutters contacting rocks on one side of saw chain, usually the cutters closest to the ground. Symptoms: Incomplete cuts, leading cuts, guide bar bound in the cut. Remedy: Replace guide bar. Replace saw chainsaw continues to cut crookedly after sharpening (see "How to Sharpen Cutters" on page 23). 9. Rail chipping in middle of guide bar. Cause: Excessive pressure on guide bar, excessive guide bar feed speed, cold conditions, lack of lubrication, aggressive saw chain cutting in frozen wood. Symptoms: Damage to saw chain and reduced guide bar life. Remedy: Replace guide bar if rail wear is extensive. Decreased guide bar feed force when cutting consists mostly of small-diameter trees. Increase lubrication, especially in cold conditions. Reduce aggressiveness of saw chain when cutting frozen wood.

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Safety & Maintenance Manual

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