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Record pace breaking thumb pins

Discussion in 'Compact Excavators' started by PeterG, Apr 27, 2021.

  1. PeterG

    PeterG Well-Known Member

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    Had an old Takeuchi TB135 with loose bushings. Broke a couple of thumb pins. Had some machined. Broke those too. Got rid of that machine. Bought a new TB240. Broke a thumb pin on that with less than 900 hours. Bought a used TB153FR with 1200 hours. Broke the thumb pin after yanking on a couple of big tree stumps. Will never do that again. Juist broke another one on that machine with about 100 hours on the pin. Most of the hours on the TB153 FR is doing rock walls. I'm the only operator. I'm on record pace for breaking pins. Does anyone know what the current record is? By the way, what brand has the largest dia thumb pins in it's weight class. Love Takeuchi, but the pins and bushings are their weak link. On a good note, I have not had any pin problems on my TB016.
     
  2. uffex

    uffex Senior Member

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    Good day Peter
    With your record I suggest you check out the positive side relief valve, you only need enough pressure to retain what you grasp it may be that this is adjusted on the high side causing the pins t break.
    kind regards
    Uffex
     
    CM1995, John C. and funwithfuel like this.
  3. Aarons81

    Aarons81 Well-Known Member

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    I have been having the same issues on my lbx 80. 4 pins in a little over a year. I just re bushed the stick and have around 200hrs so far and (knock on wood) its still going strong. Its probably going to snap tomorrow now that I said something.
     
    Vetech63 likes this.
  4. Aarons81

    Aarons81 Well-Known Member

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    I believe my pressure adjustments are correct because the bucket will move the thumb when pressuring against it.
     
  5. funwithfuel

    funwithfuel Senior Member

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    So you have hydraulically actuated thumb, not a stiff arm? If that's the case, proper setup dictates that the thumb relief be set no higher than 2500 psi. I would venture to guess your running working pressure on both circuits. No good. You're lucky you haven't broken pistons and split cans.
     
    mg2361 likes this.
  6. funwithfuel

    funwithfuel Senior Member

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    Another variable is whether or not you're using a quick coupler. That can change geometry . Can you post a pic of your configuration
     
    mg2361 likes this.
  7. Tags

    Tags Senior Member

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    It's not a Takeuchi thumb, probably a Tag thumb if it was already on the machine, used to happen all the time on a Kubota 161 I had, pin was drilled through the center for a grease channel, Kubota has changed that design now and they use a solid pin and have drilled and tapped the end of the stick to grease the bucket bushings. I have a TB260 with a Werk Brau thumb and a pingrabber coupler and haven't had any issues yet.....
     
    KSSS likes this.
  8. KSSS

    KSSS Senior Member

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    The Tag thumb is likely the issue. Pure junk. Taki finally has switched up options on their thumbs and couplers and buckets. Strickland is now available for hyd coupler and buckets. The thumbs are Strickland as well I believe. I have a Taki 257 that just came in that is the replacement for the 153. I have the Strickland hyd coupler and bucket on mine. The thumb, when it gets in, will be HPF.
     
  9. uffex

    uffex Senior Member

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    Good day Peter
    If the relief pressure is correct the problem may be what is sitting on the seat, do you continue to operate the bucket cylinder when you have grasped hold of material? To have the same issue with a number of machines indicates that the cause relates to what is the common factor. I have not seen any threads with similar issue.
    Kind regards
    Uffex
     
    Tinkerer likes this.
  10. PeterG

    PeterG Well-Known Member

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    Uffex, yes it's possible its me in the seat helping to cause the problem. The way I operate the thumb may be wrong. I typically move the thumb to wear I need it and then close the bucket. a little bucket force to pick up a brick, and more as needed. As the rocks are heavy (up to 3man size rocks or maximum lift at four feet high over the blade), I have continued to put pressure on the bucket to keep the rock from slipping. A question I have though, is the pin getting the biggest beating from using the thumb with max pressure, digging and curling under hard to extricate rocks and stumps, lifting and breaking concrete, using a 4' wide grading bucket. I never slam the bucket down, but I do press to compact soil, and lift the machine with the bucket to turn. Also, what about backfilling using the side of the bucket? What about the breaker? The TB153FR has a TAG thumb that was welded on by the Dealer. Now I think it may need a new bushing on the side that is not bolted in.


    Rockery Building Equipment.jpg
     
  11. uffex

    uffex Senior Member

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    Good day Peter
    You can establish if the thumb cylinder is suffering from overpressure by mounting a pressure measuring device, whilst the thumb has relief has the valve capacity to prevent spike pressures, nice to see you are open-minded to the cause.
    Kind regards
    Uffex
     
  12. Bls repair

    Bls repair Senior Member

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    Picking up odd size rocks could cause the pressure to be uneven across the pin. You could try having a stronger pin made ,but this may cause something else to break .
     
    Tinkerer likes this.
  13. Tinkerer

    Tinkerer Senior Member

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    tum.jpg In the photo it appears to me that the thumb is putting quite beating on the dipper pin boss.
    I would not want to see that on my own thumb.
    I'm probably wrong, but that would put tremendous pressure on the pins if the thumb cylinder is dead ended much.
     
    Last edited: Apr 29, 2021
  14. lantraxco

    lantraxco Senior Member

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    Just speaking generally, in my experience many thumb pins were manufactured with drilled grease passages, which is where they fracture from. If this is true of a pin you break, have a solid pin machined to fit, and drill all the bushing bosses for grease zerks, and if needed the end of the stick as well. You can drill down to a hard bushing and then there are a couple ways to get through the bushing, torch or a small carbon arc rod works for me. Sometimes you have to dress the ID a bit and provide a grease groove in the bushing with a die grinder and carbide burr.
     
    funwithfuel likes this.
  15. Midnightmoon

    Midnightmoon Senior Member

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    Yeah grease passage hole in center of pins is a bad idea like scoring a piece of glass. Kubota pins broke every time right in the center of the pin at grease passage. Manufacturer has told me as long as bucket can push thumb your good. Well just had one that had a broken pin about 1/3 of the way down pin. Bucket pushed thumb. I chalked it up to operator abuse because the thumb was twisted.
     
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  16. suladas

    suladas Senior Member

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    Broke a few on my 153 also, it's just a poor design every single break was in the center where it was drilled out, the first 2 broke when I had loose bushings, but the 3rd was after replacing them and everything was tight. I tapped grease ports 2 on the thumb, 1 on the coupler and 1 on the stick and got a piece of cylinder rod for a pin, and just tapped each end for a end cap. It's been working great for a year. As far as something else breaking, IMO as long as you're not abusing the machine the hydraulic cylinders shouldn't be powerful enough to break something else. The only other issue i've had with that area is cracks on the coupler but that's been happening for years.
     
    Last edited: May 1, 2021
    Tags likes this.
  17. lantraxco

    lantraxco Senior Member

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    Yep, there you go.
     
  18. PeterG

    PeterG Well-Known Member

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    Well I ordered the pin on April 21st, and I still don't have one. Dealer ordered it from Takeuchi USA. Takeuchi USA doesn't have one. I called TAG, but they will need the thumb number which I will get them today.
    Thought about getting a solid pin made, but I've done that before and seen it break again, but that machine did have loose bushings. Maybe cheaper price though. Saludas, where did you get the bushings from?
    TAG told me to check with United Rental and Sunbelt. Question: What happens if I use the machine a bit with the pin broken, as long as I keep tapping it in? I know, the bushings may wear.
     
  19. 673moto

    673moto Well-Known Member

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    You could find a way to make a solid pin until the actual TAG pin arrives.
    Or eBay?
     
  20. lantraxco

    lantraxco Senior Member

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