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500A boom

Discussion in 'Cranes' started by TVA, Jan 12, 2021.

  1. TVA

    TVA Senior Member

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    Hi guys!
    Want to see if you can help me real quick.
    Trying to pull leaking cylinder out of National 500A boom.
    The question is: is that one telescopic cylinder, or chain and block?
    Just don’t want to get myself in predicament working on unfamiliar equipment.

    Thanks in advance.
     
  2. funwithfuel

    funwithfuel Senior Member

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    If memory serves, that's a constant power boom with extend and retract cables.
     
  3. TVA

    TVA Senior Member

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    For now it looks like either double rod cylinder, or two cylinders in there.
     
  4. TVA

    TVA Senior Member

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    Anyone can share couple of pages out manual about removing boom cylinder out of that one?
    I got scammed today trying to buy PDF download online, now I have to cancel the credit card.
     
  5. TVA

    TVA Senior Member

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    I have attempted removing just a very front section separately, because I didn’t want to handle the whole thing on the ground. But section wouldn’t come out about a foot not reaching the end.
    The pin was removed, the stop was removed also.
    There’s no inspection holes in the middle section through which I can look in to see what is going on.

    My theory is that cylinder rod catches on something inside the section and wouldn’t let that section come out.
    Manages to push section in and re install the pin back in.
    If I am not going to get any help from forum, I will try to remove two sections together tomorrow.
     
    Last edited: Jan 13, 2021
  6. funwithfuel

    funwithfuel Senior Member

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    Can you post a pic of the picture frame from base of boom? How many sections of boom, 3 or 5?
     
  7. crane operator

    crane operator Senior Member

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    Every national I've had apart, is single cylinder with cable extend. Pull the hoses at the rear, detach cylinder and block cylinder up in boom if required, pull all boom sections out of the base, with cylinder staying with the extension sections. Most times you can lay that group of sections on a trailer or blocks, and just rebuild the cylinder there, if you don't need at the barrel for honing etc.

    But I've never done one as small as a 500. Everything I've done is 4-5 sections booms.

    I can send you copies of the procedure from a larger national boom if you think that will help you.
     
  8. TVA

    TVA Senior Member

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    I can probably do pictures tomorrow.
    3 sections.
    The rod end (eye) in the first section - hook end.
    Also rod end, with six bolt fastening the block with counterbalance valves to the wall, just on the other side of hoist
    Looks like both hydraulic lines go through the channels drilled inside of this rod, and going to the barrel somewhere in the middle section.

    Still can’t see weather it is double rod cylinder or two separate cylinders sequentially connected.
     
  9. crane operator

    crane operator Senior Member

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    If you have a serial # and talked nice to the national/ grove dealer, they will send you the pages from the manual- they have access to those at their computer in the service dept. Depending on age of the boom.
     
  10. TVA

    TVA Senior Member

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    Thanks!!!
    I’ve seen some service bulletins for booms with wire ropes and blocks online.
    Unfortunately it is not what I am dealing with!!!
    I don’t see anything suggesting wire rope connections anywhere on that boom, all I see is two rod ends on both sides and barrel body in the middle. That boom have very limited amount of holes you can look through!!!
    Thank you!!!
    This is a very good idea!!!
     
  11. crane operator

    crane operator Senior Member

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    It could be built like my allis forklift which has a rod going each direction from a single barrel.

    Still, removal should still be the same. Take bottom rod loose from the bottom/ base end, slide all sections out. Then the barrel likely unbolts from section #2 and you may have to then pull section # 2 from section #3. The upper rod still attached to #3. (Maybe:))
     
  12. TVA

    TVA Senior Member

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    I think you’re right.
    Just didn’t feel like handling the whole assembly, so tried to take it apart section by section.
    It didn’t work out.
    Tomorrow will try to pull the whole thing together.
    Would you suggest to stretch the whole boom out, or suck it in? Which way is better?
     
  13. crane operator

    crane operator Senior Member

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    Fluid travel rods usually have one pipe welded inside the hollow rod. Extend fluid in hollow rod and retract fluid in the pipe or the other way around.

    I leave the base section in the frame. Push out only 6-8" if you need to work inside base. Attach forklift to tip. Pull both sections until center of gravity is outside the base section (measure length to determine center).

    If you have two lifting devices, you can pull with one and lift the boom with the other. Otherwise lift the section in the center and drive the truck and base section from the others. If you don't want to do this all 10' off the ground, you can pull base with all the sections, and do the same thing on the ground on cribbing. I like to leave the base with the crane, because then its anchored for pulling and shoving back together, but I've got all kinds of lifting equipment.
     
  14. TVA

    TVA Senior Member

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    Thanks!!!
    I have no interest to touch base. All I need is to find and eliminate a leak!
     
  15. crane operator

    crane operator Senior Member

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    Its probably lost the seal, there's not much else in there.

    Here's how I pull boom. upload_2021-1-12_21-5-28.png
     
  16. TVA

    TVA Senior Member

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    Well it’s out.
    And there’s two cylinders! 645981FD-0DAF-4EFF-ACB8-2E3B9DBAEE8E.jpeg
     

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  17. crane operator

    crane operator Senior Member

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    Can you tell which one's leaking? Given that you are this far, you just as well do them both. Hydraulic shop will match up seals, they won't be anything exotic, probably just z type and orings.

    If its the bottom one, you can pull the nut and leave the barrel in the boom section. It will all need to slide off the far end. The upper one may be able to pull those keeper blocks, and slide the barrel out far enough to get at the nut and leave the rod on the boom tip section.
     
  18. HATCHEQUIP

    HATCHEQUIP Senior Member

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    definitely want to do both and all the hoses in there too and look at all the wear strips and put some boom lube on those sections as you put them back together , pics look dry.
     
  19. TVA

    TVA Senior Member

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    1CEFAF8A-1598-48DB-9BCD-BC43F5019656.jpeg 1CEFAF8A-1598-48DB-9BCD-BC43F5019656.jpeg So the problem I’m having now is I can’t pull the front section out 1 1/2 feet to take pin out which I took out yesterday.
    I wrapped the chain around middle section because there’s nothing on the middle section too hook to.
    Two excavators pulling, one broken chain, customers operator even tried the vibrating plat on the middle section ( against my warnings) - it just wouldn’t budge!!!
    The top cylinder is loose on the back end.
    I didn’t see any levers at the rod eye that would operate mechanical lock - simply two holes thorough the walls of the front section and pin that go through those holes and the rod eye.
    Don’t see any other hydraulic lines anywhere with which hydraulically operated mechanical lock would be controlled!
    And why would it be mechanical lock between front and middle section, but not between middle and rear section.
    I understand that there’s whole lot of crap in there ( oil mixed in with sand, dirt and other crap), just not sure if it can lock up like that?!?!

    This thing is sequential, because of that I had to suck front section in to middle section to retract the middle section in to the rear section to not to have the whole thing too long and protect the rod from damage!!!
    When I was retracting everything went smooth and I didn’t hear any load at all on the pump or the engine.
    Engine was at idle but I over shot the first
    Inspection hole and wanted to come back and boom didn’t want to extend ( it extended OK yesterday when I just started working on it).
    As oil was leaking heavily from the boom, I thought that maybe seals just bad and wouldn’t build the pressure, so I proceeded to remove front and middle sections together out of rear section.

    Now I am astonished as why in the hell it locked up like that, and at this point I don’t know about anything else I can do beside take the bolts out of the slider pads ( the ones I can do from the outside) and hoping that it’ll help to get things loose!!!

    If you guys have any info or ideas about the prob I am having - pleas share!!!
    Anything will help!!!
     

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    Last edited: Jan 13, 2021
  20. TVA

    TVA Senior Member

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