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Welding Dragline Crane Boom Tip Sheaves

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  • Welding Dragline Crane Boom Tip Sheaves

    Looks like I'll be rebuilding my existing sheaves as I haven't been able to find anything in better condition at this point. Rebuilding the center with a new bronze bushing to turn on the new shaft should be no big deal, I do have a question on the cable grooves. My cable grooves are well worn as seen in the picture, I'm worried that there isn't much material left in this area and that the cable will soon wear through if I don't do something. I have heard of folks who build up weld in the groove and after building this up turning smooth and true on the lathe. I was going to give this a try but thought I would ask if anyone has done this before or has some advice, I was going slowly turn the pulley on a shaft while welding with Mig gun (GMAW). How much buildup should the sheave have, or in other words how deep should the cable ride in the sheave? This sheave will be running 1/2" cable. One picture shows the sheave, the other the groove which I would like to build up. Thanks.

    Bryan
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  • #2
    Well at 2" deep i would say they got their moneys worth from that pulley. I would think if you filled up an 1 1/4" of that it would be fine. There is prob some leeway so the cable doesn't jump off but i don't know how much. Post some pics when its done. Is the pulley cast iron or cast steel?...Bob

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    • #3
      I would be more worried about cracking the spokes, and using the correct filler material. Is this sheave cast iron or is it steel? Are you sure you can't get something similar from a bearing supply house? Might be a blank, have to put the hole/bushing in the center yourself. Cable sheaves are still being made, and used everyday.

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      • #4
        Originally posted by JSFAB View Post
        I would be more worried about cracking the spokes, and using the correct filler material. Is this sheave cast iron or is it steel? Are you sure you can't get something similar from a bearing supply house? Might be a blank, have to put the hole/bushing in the center yourself. Cable sheaves are still being made, and used everyday.
        Or have a buddy with a lathe spin you one out of steel plate. No problem there...Bob

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        • #5
          The correct answer for the depth of the cable in the sheave can be found in a pub called Machineries Handbook. I think it is in it's 28th edition now. The center bushing and pin are easy, as long as the sheave is weldable it too can be rebuilt. But the exact base material must be accurately determined to insure that the sheave isnt degraded by heat/wrong filler. Interpass temps and max temps management as well as pre and post weld heat treatment will probably be required to restore original strength and ductility. Something a full service welder or foundy should be able to assist you with. Probably something left to a little more experienced individual.
          Bob

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          • #6
            sheave repair

            From your pictures the sheave doesn't appear to have much more that a half inch of wear in the groove. These sheaves are made of alloy steal for the most part. check to make sure it is magnetic ( magnet sticks to it ) there have been some older sheaves made of Mangenese and are not able to be rebuilt. a sheave this small can easily be fabricated. but nothing is cheep anymore. Modern Machine Works in Bismarck ND does these kind of repairs frequently. Good Luck

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            • #7
              boom tip sheave repair

              This sheave is not wore bad at all !!!!!!!!! I hope you have not filled this sheave yet. on top sheaves I NEVER SEEN ONE THAT FULL. When I would help my dad an uncle work on them the new sheave would have about 1" above the top of the cable so it would not come out of the sheave when you put side pressure on it to turn the bucket with it and the haulback or drag cable this sheave looks like it is in a single sheave set up the sides are in good shape do not put welds on over 5/16 or smaller this way you mix some of the base metal with the filler . I would use .035 argon/co2 an the wire something comparable to Lincoln superarc L-56 . To me the worst part I see is the bushing what size and brand machine is this on ? Is this on a 3/8 or1/2 yard machine??? KEEP YOUR BOOM UP AN UNDERCARRAGE DOWN !!!!!!

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