Guide Bar
89 Mechanical Timber Harvesting Handbook
Mount Conditions
18. Spread or broken guide bar
mounting slot.
Cause: Holding pins/bolts were not
inserted into the guide bar mount holes.
The guide bar is not properly supported
when minor accidents or pinches occur.
Symptoms: The guide bar mount slot
spreads or the guide bar breaks at the
slot prematurely. If a Jet-Fit
®
guide bar
fails from the tip of the middle slot to
the side as shown without the small tab
also breaking, then pins are missing or
broken off.
Remedy: Replace broken guide bars
and use the holding pins/bolts originally
supplied with the guide bar holder.
When purchasing a new harvester head,
consider purchasing head compatible
with Jet-Fit guide bars.
Jet-Fit Mount Conditions
19. Chronic or frequent guide bar
mount breakage on Jet-Fit guide
bars when no accident has occurred.
Cause: The guide bar retraction speed is
too fast. The forward guide bar-sweep
speed is too fast, causing the guide bar
holder to stop quickly at the end of its
rotation.
In either case, the inertia of the guide
bar causes it to over-rotate in the guide
bar mount, putting excessive stress on
the guide bar mount.
Symptoms: Guide bar breakage without
the guide bar being involved in an
accident. Unexplained guide bar mount
breakage.
Remedy: Reduce pressure, or flow, to
the cylinder that sweeps the guide bar
forward, out of the saw box, or retracts
the guide back into the saw box.
Guide Bar Troubleshooting
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