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Boom Lift salvage yard

Discussion in 'Other Construction/Demolition Equipment' started by Ronray, Sep 6, 2019.

  1. Ronray

    Ronray Well-Known Member

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    20190403_192905.jpg Looking for Boom Lift or man lift salvage yards. I am specifically looking for a drive brake valve block assembly for my 1980 marklift 60 foot boom lift.

    I cannot find the new part which is part number Terex 21082.

    Also attached is a picture of the ID stamp on the block assembly which shows it as Fluid Controls Inc out of Mentor Ohio with some numbers stamped on it. But that hydraulic controls company was apparently sold or out of business.
     
  2. Ronray

    Ronray Well-Known Member

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    Help please anyone?
     
  3. mikebramel

    mikebramel Senior Member

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    Whats the problem
     
  4. chroniekon

    chroniekon Well-Known Member

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    It's a long shot, but try Farmland Tractor in Tangent, Oregon
     
  5. Ronray

    Ronray Well-Known Member

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    Not enough hydraulic pressure and volume going to the hydraulic wheel drive Motors. Only 1200 lb.

    I have 2500 lb hydraulic pressure, which is the maximum for the pump, going into the drive brake valve block for both forward and reverse lines, but only 1200 lb coming out of the forward and reverse lines going to the hydraulic wheel Motors. So I suspect an internal leak or malfunction in the drive brake valve block.
    When I cap off all four of the exit lines from the valve block and blow into one of the inlet ports with my mouth, air comes back out the other Inlet line port. So I suspect that there is a leak between the two Inlet ports inside the block?

    20190808_232743.jpg
     
  6. Ronray

    Ronray Well-Known Member

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    Here is a different part number from the PDF manual hydraulic schematic page for this drive brake valve block 21214.
     
  7. funwithfuel

    funwithfuel Senior Member

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    Could it be the relief valve on one of your travel motors is dumping to tank too soon
     
  8. funwithfuel

    funwithfuel Senior Member

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    What if you were to cap the ports for the hoses going to each of the travel motors what would your pressure be then
     
  9. Ronray

    Ronray Well-Known Member

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    Thanks fun I will have to do some more testing that way.

    Where does the hydraulic fluid go after the travel motors forward function is engaged? Does it all go back to the main hydraulic tank reservoir through the small relief hose from the travel motor, or does most of it go back through the reverse hose?
     
  10. funwithfuel

    funwithfuel Senior Member

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    Should return through opposite hose back through control valve and then to tank. Typically, you'll see 3 maybe 4 hoses to each motor. 2 beefy ones will be your A/B travel . Next size down would be case drain and the dinky one if it has it, should be for 2 speed change over. I would want to see the oil pressure going to each motor one by one capping off all others. This way you are removing consumers as a source of loss.
    Good luck.
    CAUTION!!!! Do not cap all ports, it may leave you with a "No Relief" condition.
     
    Vetech63 likes this.
  11. Ronray

    Ronray Well-Known Member

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    I assume the A/B travel means the beefy forward and reverse hose lines?

    Not sure what you mean with the word "consumers", internal leaks with other components, such as a drive motor or valve Bank?

    I previously capped off the beefy reverse hose before the connection to the drive brake valve bank, and attached the pressure gauge to the inlet beefy hose before the valve bank and it held at 2500 lb and did not blow any lines out. So I'm assuming that there must have been some kind of relief valve between the proportional valve manifold and the drive brake manifold?
     
  12. funwithfuel

    funwithfuel Senior Member

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    I use consumer to describe "the thing that does work " whether a cylinder, motor whatever. Sorry for the confusion
    I describe electrical systems in the same manner. Consumers use energy to do work.
     
  13. TVA

    TVA Senior Member

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    This is a third or fourth thread you started about the same machine! It’s been almost half a year, I don’t remember all the details when the previous is ended.
    Did you know for sure you have a crack in that block or you only think you have a crack?
     
  14. TVA

    TVA Senior Member

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    As far as I remember that machine does not have a relief valve in the motors, counterbalance valves are in that block and high speed shifts by mechanical linkage from cylinder which takes its supply from the same block and shares it with steering circuit.
     
  15. Ronray

    Ronray Well-Known Member

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    Thanks fun. Now I understand what you mean by consumers.
     
  16. Ronray

    Ronray Well-Known Member

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    Yes TVA, I have had several issues with this machine, and this post got into another issue when senior member Mikebramel asked me what the problem was, why was I looking for a used drive brake valve block.

    No, I don't know if there is a crack inside the block, that was just suggested to me as a possibility by a service manager a lift boom rental company.

    So I took the valve block to a hydraulic shop yesterday and the service man there thinks that the spring ball and seat in the block in the attached picture may be causing a leak inside the block between A&B Inlet large beefy lines, even though he could see no scratches or other defects with the naked eye. The service man said that with all of the exit block lines capped off, when you blow into the one Inlet beefy line coming into the valve block, that there should not be air coming back out the other beefy line port.

    20190328_202305.jpg
     
    Last edited: Sep 13, 2019
  17. TVA

    TVA Senior Member

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    That looks like check valve, I highly doubtful that it is not doing it’s job if there’s no damage to seat or a ball, unless spring installed wrong or ball of wrong size.
    You should have two of them there! If one leaks and the other doesn’t - take both out and compare to each other, I think the seats for them is inside the block and not in the cap!
     
  18. Ronray

    Ronray Well-Known Member

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    Yes the seat is inside the valve not the cap. I will compare the two balls with a micrometer.
     
  19. Ronray

    Ronray Well-Known Member

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    TVA, I got an email notification of a post you made at 7:15 a.m. this morning, but post does not appear in this thread?

    Following is the text that appeared in the email:

    [​IMG]
    If that is counterbalance valve - there’s should be a pilot line passage between two ports! That’s how return to tank side gets opened up when you have pressure on on pressure side!

    On the other hand counterbalance valve can leak out your pressure to drain port if it’s damaged. And drain is not the same as return, although it connected to it.
     
  20. Ronray

    Ronray Well-Known Member

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    So if I understand correctly, each counterbalance Dynamic brake valve uses the travel wheel hydraulic motors as a braking mechanism, kind of like an engine brake in a truck? And the heavy duty springs adjustment determines the stopping distance from 1 to several feet? And after it stops then the parking brake kicks in?

    And it looks like the mechanical brake drum in the wheel hub is really a parking brake since there is just one small hydraulic line going to one small adjustment needle on the drive brake valve cylinder block?