Smalljobs
Gold Member
We've come across a situation where the chipper owner first experienced infeed roller failure slipping on a new chipper and later reported the small driveshaft "falling off". Before we had a chance to look at it, the owner had welded each end of the coupling. The feed roller end coupling was welded to the end of the infeed roller shaft, and the other end was welded to the outer dog clutch.
The meant we were unable to determine if the spring force was adequate to keep the couplings engaged to their respective ends. When compared to a known good spring, the heights were the same.
The worm drive roller feed gearbox was found to be at the extreme far left limit (line to line contact with end of upturned bracket holding jackscrews) and the original belt was intact. Chipper is only 3 months old. The input pulley of the worm drive box showed some runout and the output shaft was bent.
We found the coupling welded to the outer dog of the worm box was not true and certainly had runout. It was impossible to disengage the feed roller with the lever as the shaft and spring could not be compressed, i.e., the shaft could not contract.
Upon final disassembly it was found the male end of the drive shaft, closest to feed roller, was bone dry and had a significant twist, rendering it impossible to shorten its own length. It could not accept the female counterpart that makes up the other half of the shaft. The twist seemed to be at the last 50% of shaft length.
It also meant that if the feed roller moved upward to feed larger diameter branches, the shaft could not contract, and it generated an upward force directly to the output shaft of the worm drive.
I'd have thought the belt would have slipped before allowing the feed roller shaft to twist.
One theory is that perhaps the chipper was never lubed on the roller feed drive shaft and then after chipping some large diameter, the dry shaft failed to extend fast enough when the feed roller dropped off the butt end the limb/log.
Has anyone come across this? Any ideas before we replace all the parts?
The meant we were unable to determine if the spring force was adequate to keep the couplings engaged to their respective ends. When compared to a known good spring, the heights were the same.
The worm drive roller feed gearbox was found to be at the extreme far left limit (line to line contact with end of upturned bracket holding jackscrews) and the original belt was intact. Chipper is only 3 months old. The input pulley of the worm drive box showed some runout and the output shaft was bent.
We found the coupling welded to the outer dog of the worm box was not true and certainly had runout. It was impossible to disengage the feed roller with the lever as the shaft and spring could not be compressed, i.e., the shaft could not contract.
Upon final disassembly it was found the male end of the drive shaft, closest to feed roller, was bone dry and had a significant twist, rendering it impossible to shorten its own length. It could not accept the female counterpart that makes up the other half of the shaft. The twist seemed to be at the last 50% of shaft length.
It also meant that if the feed roller moved upward to feed larger diameter branches, the shaft could not contract, and it generated an upward force directly to the output shaft of the worm drive.
I'd have thought the belt would have slipped before allowing the feed roller shaft to twist.
One theory is that perhaps the chipper was never lubed on the roller feed drive shaft and then after chipping some large diameter, the dry shaft failed to extend fast enough when the feed roller dropped off the butt end the limb/log.
Has anyone come across this? Any ideas before we replace all the parts?
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