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Antique Back Hoe Repair

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  • #31
    Measure the OD of the packing nut and you have a good idea of the piston diameter. Multiply that by 1.5 = square inches of piston. Multiply by 1000 (average working pressure unless the machine is breathing fire) and you have the developed force at the cylinder/dipper pin.
    Quick & dirty ratio calculation says 75% of that force will be delivered to the dipper/bucket connection.

    More quick & dirty says you put 4000# into the dipper at the top, you get roughly 3000# at the bucket connection, BUT, that isn't the center of the bucket where actual force counts.
    Deduct some force for the weight of the dipper below the fulcrum as well, and you have a machine that may deliver 1200 pounds of breakout.

    When I look at a job like this I always ask WHY the guy did it to start with.
    You said the machine spent its early life digging septic tanks, that isn't much more than a 5 foot deep hole for 300 gallon tanks that were popular back when the machine came to work. The machine might well have come on the job with the longest dipper the company built.
    Looks to me like someplace in the machine's life somebody wanted more breakout than it had, so they shortened the dipper. Not much else makes sense.

    Problems started as the job was improperly done, and got a lot worse as patches were added.

    Still, at this point, it is fixable. Burn out all the steelcrete the mason helper trowled on, and pull the plug and replace it with a proper plug, and drill or burn some holes in the dipper to allow welding the plug to the dipper properly at both ends and near the joint. You can add length or not as you desire.

    Alternate- find a piece of Schedule 40 pipe and build a replacement dipper to desired length. Might be faster, and you can reenforce properly for strength at the fulcrum point which appears to be the weak link in the machine.

    600 mile thing, either move the machine to the selder or take an engine drive to the machine. That's way too much cable to roll out.

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    • #32
      The only schedule 40 pipe I know of is only around 1/8" or slightly thicker for 3 1/2" od. I am going to half inch wall.

      I was looking at ideas for bracing. A couple of home made back hoes are connected to a front to rear sub frame. If I keep the hoe on this tractor I'll make one for it.
      Thanks Franz

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      • #33
        From the first pics posted it appears the tractor already has a lot of bracing for the dozer blade.
        Can't really tell if it just comes back to the bell housing or all the way to the rear X.
        Weak point on those tractors is where the bell marrys to the engine and the bell itself.

        Sub frame under the rear X is certainly possible, Woods seems to do that on hoes for small tractors pretty nicely.

        My first idea would be marrying the back of the dozer frame to the front of the hoe subframe, with some flex in the marriage. Too stiff ain't necessarily good in a machine of that size.

        Take a good look at the front wheel bearings & spindles as well they take a pounding with a hoe.

        You also mentioned wobble when on the outriggers. That ain't a good thing, and is probably due to air in that system. Bleeding may solve the problem.

        I think I mentioned it before, but just in case, pay particular attention to the pins & bushings. Slop in them is an expensive repair waiting to happen.

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        • #34
          3 1/2” pipe with roughly 1/2” wall thickness is sch 160 range.

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          • #35
            3" nominal Sch 80 is 3.5 OD with a .300 wall.

            https://www.engineersedge.com/fluid_...chedule-80.htm

            It weighs a little over 10 pounds per foot and would be a workout for my hydraulic 20 ton bender.

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            • #36
              Originally posted by Franz© View Post
              3" nominal Sch 80 is 3.5 OD with a .300 wall.

              https://www.engineersedge.com/fluid_...chedule-80.htm

              It weighs a little over 10 pounds per foot and would be a workout for my hydraulic 20 ton bender.
              Still to thin for my use. I am stepping up from 3/8".

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              • #37
                3 1/2” sch 160 is closer to the 1/2” that you wanted. It’s .437 according to the fancy pipe sch chart.

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                • #38
                  I am redoing all the pins when I replace the pipe. I have an estimate of $245 delivered from Industrial Tube and Steel in Kent, Ohio. 3 ½" X .500" X 54", shouldn't be much more for the longer pipe.

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                  • #39
                    https://apexpipe.com/

                    http://midstate-steel.com/specials.html

                    https://www.pitpipe.com/used-steel-pipe.html

                    http://specialtypipe.com/

                    Your insistence on .500 wall is putting you on a very expensive road.

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                    • #40
                      Originally posted by Franz© View Post
                      Yes but going thinner than what broke does not make sense to me. Fixing it once and calling it done does. Thanks for the links. Didn't know about Apexpipe.

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                      • #41
                        I tend to over build things as well. You’ll just have extra work in making sure you get the full penetration welds. A little extra grinding and fitting really. But not doing so is a waste and you could’ve just used thinner wall stuff. So you’ll end up with multi-pass welds to accomplish this re-do. You got lined out what process for this undertaking?

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                        • #42
                          Go back to the picture of the fulcrum area showing the gap and plug inside the attempted repair.

                          That pipe was cut & beveled.

                          What broke wasn't the pipe, it was the halfazzed attempt to weld.

                          I can clearly see it.

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                          • #43
                            Originally posted by ryanjones2150 View Post
                            I tend to over build things as well. You’ll just have extra work in making sure you get the full penetration welds. A little extra grinding and fitting really. But not doing so is a waste and you could’ve just used thinner wall stuff. So you’ll end up with multi-pass welds to accomplish this re-do. You got lined out what process for this undertaking?
                            Not entirely. I have been digging through this site though. Ideally I would take it to a shop that has all of the equipment and experience to stick this together in a day or two. Would be nice to start out with a new set of brackets, but that is not in the budget nor at my big headed pride in doing everything myself. It will likely be after the 1st before everything comes together.

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                            • #44
                              When I rebuilt my gates I heated the thick metal yellow and fused it to the 22? gauge walled fence. Not sure if that is text book but it's been working on other projects. I know what a good weld and penetration looks like. Problem is by the time it comes off the stick it is not like what I imagined.

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                              • #45
                                Ha! Sometimes it goes like that and I know the feeling with the hardheaded bit. What sort of equipment do you have available? Gear stout enough to tackle this repair? If you do, go for it. It’s broken now, it’s not like you’ll break it worse.

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