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  1. #1
    Gold Member Smalljobs's Avatar
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    Jinma 284

    Default 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    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?
    Attached Thumbnails Attached Thumbnails -bent-worm-shaft-jpg   -twisted-shaft-jpg  
    Last edited by Smalljobs; 12-05-2011 at 09:12 PM. Reason: Typo
    Steve Anderson

    Jinma 284LE w/Creeper/Koyker 160 Loader/Markham Toothbar, Frame mounted HWO4X backhoe, 64" John Deere 3 PH Snow blower,3 PH splitter, Bro-Tek thumb, Jinma 8" chipper, Loader mounted Meyer plow

  2. #2
    Super Member greg_g's Avatar
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    Western Kentucky
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    JD3720 Cab, 300X loader with 4-in-1 bucket

    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    Assuming the owner didn't alter the spring as well, it's got more than sufficient strength to hold the male/female halves together. In fact - as you'll find - it's so strong that I'm gonna wear gloves when installing my own new shaft. The U-joint separated on the outside end - which effectively disconnected the shaft from the gear reduction box - at which point the spring decompressed, allowing the driveshaft halves to separate.

    Matter of fact, mine's still down. Dealer here seems to be having great difficulty in obtaining for me a new half shaft

    //greg//
    USN (Ret)
    Former Chinese tractor owner (x4)
    Current John Deere owner

  3. #3
    Gold Member Smalljobs's Avatar
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    Jinma 284

    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    Greg - After seeing the belt tightened to the limit and worm gear box as far as possible to the left, I'm wondering if somehow the infeed roller stalled and the exposed portion of the inner drive shaft became twisted due to a combination of high input HP as well as a belt so tight as to not slip?

    Then when the roller dropped, the drive shaft could not collapse and, in fact, the twisted portion was driven into the female half...like hammering an "EZ OUT" into a hole. Perhaps it's possible in that scenario for the shaft to be stuck in the shortened position and unable to lengthen itself as driven by the spring. The shaft might then fall off. His complaint was the shaft was falling off and that's why the ends were welded. The free height of the spring was same as a known good spring.
    Steve Anderson

    Jinma 284LE w/Creeper/Koyker 160 Loader/Markham Toothbar, Frame mounted HWO4X backhoe, 64" John Deere 3 PH Snow blower,3 PH splitter, Bro-Tek thumb, Jinma 8" chipper, Loader mounted Meyer plow

  4. #4
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    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    I have seen several chippers that did not have the stops on them, the stops will only allow the feed roller to raise a certain height, if it exceeds that height the angle is too much and the shaft breaks.Seems that may be the problem here

    Tommy
    Affordable Tractor Sales
    "Your Jinma Parts Superstore"
    Home of compact Jinma, Foton, and Koyker Tractors and Parts, Wood Chippers, Backhoes - Affordable Tractor Sales Company

  5. #5
    Super Member greg_g's Avatar
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    JD3720 Cab, 300X loader with 4-in-1 bucket

    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    After our conversation, I'm more inclined to believe that the male half-shaft was likely defective, possibly a bad weld between the hex rod and the U-joint. That caused the spring to slip and the driveshaft to drop. This may or may not have been aggravated by previous ill-advised welding on the U-joints themselves.

    //greg//
    USN (Ret)
    Former Chinese tractor owner (x4)
    Current John Deere owner

  6. #6
    Gold Member Smalljobs's Avatar
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    Jinma 284

    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    The amount of exposed twisted shaft could happen if a 7" or larger log was under the roller. If the roller could not feed and the belt could not slip and the tractor could not stall...something had to give.
    Steve Anderson

    Jinma 284LE w/Creeper/Koyker 160 Loader/Markham Toothbar, Frame mounted HWO4X backhoe, 64" John Deere 3 PH Snow blower,3 PH splitter, Bro-Tek thumb, Jinma 8" chipper, Loader mounted Meyer plow

  7. #7
    Elite Member RonMar's Avatar
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    Port Angeles WA
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    Jinma 284 delivered 06/28/05

    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    Yep, something had to give. I have found on my 6", that it is virtually impossible to disengage that little coupler on the gearbox output with the feed roller under load. I have had a few occasions where something just a little too large has made it down the chute, and jammed there. Either the feed teeth slip, or the belt does. Now if some fine green bark strings have wound their way around that center shaft and made their way into the pully, the bellt can get VERY tight. That with good sharp roller teeth and the next weakest link is getting ready to be found...

    Welded a little piece of angle iron in along the shaft on mine to act as a cutter/scraper to keep the stringy stuff from collecting around the middle. Going to add a springloaded idler pully to control the feed roller belt tension and allow me to positively disengage the feed roller in an emergency with the safety bar, or whenever I feel the need...
    Ron

  8. #8
    Gold Member Smalljobs's Avatar
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    Jinma 284

    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    I took some fast rough measurements, and could be wrong, but it seems the roller can lift higher and accept a log larger in diameter than the actual opening into the flywheel. If so, the roller cannot possibly feed it. The chipper involved is one of the new "8" .
    Steve Anderson

    Jinma 284LE w/Creeper/Koyker 160 Loader/Markham Toothbar, Frame mounted HWO4X backhoe, 64" John Deere 3 PH Snow blower,3 PH splitter, Bro-Tek thumb, Jinma 8" chipper, Loader mounted Meyer plow

  9. #9
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    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    We offer a Heavy duty feed driveshaft for this chipper,here is a pic.

    Tommy
    Affordable Tractor Sales
    "Your Jinma Parts Superstore"
    Home of compact Jinma, Foton, and Koyker Tractors and Parts, Wood Chippers, Backhoes - Affordable Tractor Sales Company
    Attached Thumbnails Attached Thumbnails -4e87397087131dsc00837-jpg  

  10. #10
    Super Member grsthegreat's Avatar
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    dk45se hst cab

    Default Re: 8" Jinma Chipper Infeed Roller Feed Shaft Twisting

    Quote Originally Posted by Affordable View Post
    We offer a Heavy duty feed driveshaft for this chipper,here is a pic.

    Tommy
    Affordable Tractor Sales
    "Your Jinma Parts Superstore"
    Home of compact Jinma, Foton, and Koyker Tractors and Parts, Wood Chippers, Backhoes - Affordable Tractor Sales Company
    Im not having any issues with mine.... and i keep it lubed and oil filled after every use. But how much is your drive shaft...?
    currently own
    2011 Kioti DK45SE HST CAB tractor/loader, Jimna 6" - 3 point wood chipper, 60" JD Brush Hog, JD 60" Rototiller, 3 point post hole digger with hydraulic assist, 3 point spring tooth rake, Fimco 55 gallon weed sprayer with 12 foot boom, 3 point hydraulic wood splitter (home built)
    Quick Attach 79" loader mount snowblower & rear powerpack
    Quick Attach 84" Snow Blade
    Quick Attach 42" pallet forks

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