38
39
Rails in the tip of a sprocket- nose guide bar have spread, allowing loss of bearings. Remedy: See Y.
The sprocket in a sprocket-nose guide bar breaks. Remedy: See Y.
Remedies: T. Shallow grooves and wire edges are the result of normal wear over time. Use a flat file to square up the guide bar’s rails and remove wire edges promptly. Left alone, wire edges can break off, chipping away good rail material, (pictures 31 and 32)
U. A thin or low rail is caused by one of two things: (1) crooked- cutting saw chain, see pages 55, or (2) saw chain leaning over in a worn groove, see picture 23, page 53. Replace the guide bar. Replace the saw chain as well if saw chain continues to lean in the new guide bar. (picture 33)
V. Accidents or irregular operating techniques which push the drive links sideways or place excessive pressure on the side of the nose can cause breaks or cracks in the rails of solid-nose guide bars. Your dealer may be able to repair minor damage on a relatively new guide bar. (pictures 34 and 35)
W. Pinched rails, lack of lubrication, or accidents and cutting techniques which push the drive links sideways in the groove can create extreme friction which causes blue discoloration. Blue spots on rails are soft and will wear rapidly. Replace the guide bar. (picture 36)
X. Such wear or chipping near the nose often accompanies heavy limbing, but can also be caused by loose saw chain tension. Invert the guide bar on the chain saw periodically to reduce such wear. On replaceable-nose guide bars with minor wear, install a new nose and file down the nose’s rails as shown on page 63 for smooth saw chain flow. If wear is extensive (on solid-nose or replaceable- nose guide bars), replace the guide bar. (picture 37)
Y. Frequent boring cuts, loose saw chain tension, and accidents or irregular operating techniques which twist the nose or push the drive links sideways against the nose’s rails will cause such breakage. Install a new replaceable sprocket nose if possible, otherwise replace the guide bar. (pictures 38 and 39)
67
GUIDE BAR
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