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Boom Lift salvage yard

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

  1. TVA

    TVA Senior Member

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    Did everything moved freely and no damage visible?
     
  2. Ronray

    Ronray Well-Known Member

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    Yes everything moved freely with no visible damage.
    So if I am getting 2500 lb PSI coming into the valve block, should I still be getting 2500 lb going out to the drive Motors when I have the gauge on one outlet and the three others capped off?

    Considering that there is a drilled hole between the two Inlet ports inside the block, I would assume that fluid and pressure would be leaking back through one of those Inlet lines? And I would wonder where does that fluid go, back to the storage tank or back to the proportional valve manifold?
     
    Last edited: Sep 16, 2019
  3. TVA

    TVA Senior Member

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    The drilled holes between inlets should go to shuttle valve cavity, to supply pressure for speed shift and parking break. Shuttle valves job is to open passage to high pressure side and close to low pressure ( return) side.
     
  4. TVA

    TVA Senior Member

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    The return goes to tank, but it goes THROUGH proportional directional control valve.
    That valve ( MCV Main Control Valve ) is primarily Directional, I.e. changing direction of movement, the question of weather it is Full ON/OFF or proportional comes secondary. But we just like to call it MAIN Control Valve without specifying what type. They can also be open center or closed center, load sensing or non load sensing and have boat load of different actuation methods and combination of those and whole lot of different things.
     
  5. TVA

    TVA Senior Member

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    So right now main question is: are we bypassing or restricting?!

    If inlet pressure will slowly drops a short while after actuation ( driving ) - then it is bypassing back to tank. If it’s staying pretty much close to same - then most likely it’s restring the flow.
     
  6. TVA

    TVA Senior Member

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    Another thing that can bypass is counterbalance valve through those internal parts, pilot lines to tank. Got to pay attention to all the spoils and O-rings. Although internal crack is very much possible!
     
  7. Ronray

    Ronray Well-Known Member

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    So when the return line goes through the proportional directional control valve, I assume that the return line is one of the big beefy lines either forward or reverse line?
     
  8. TVA

    TVA Senior Member

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    Yes, you switch them around by moving MCV spool.
     
  9. Ronray

    Ronray Well-Known Member

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    So I may have to reverse the sleeves over the Pistons in the counterbalance valves in the attached picture? I can't remember which direction they were when I took them out LOL
    I suspect the top one in each picture is the more correct configuration since if it was the other way, part of the O-ring would be in the path of the incoming fluid in the cavity.


    20190915_205900.jpg 20190915_205955.jpg
     
  10. TVA

    TVA Senior Member

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    Are those two was in the same cavity?
    If they were, it is shuttle valve ( why it is so big I have no idea), shuttle valve supposed to close the passage between low pressure inlet to speed shift/park break passage, leaving only high pressure side connected, and when you reverse direction - switch everything to another side.
    You noticed that barrels have different ends, I think one goes inside block to blind end, another to cap end. Put it’s for you to figure out which goes where.
     
    Last edited: Sep 17, 2019
  11. Ronray

    Ronray Well-Known Member

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    No they are not in the same cavity, they are in separate cavities. Each one is in a cavity for each dynamic Drive brake counterbalance valve.
     
  12. Ronray

    Ronray Well-Known Member

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    So I reconnected the drive brake valve block to the 2 in coming forward and reverse big beefy hoses and did a pressure check on each of the 4 exit beefy lines, and each one measured at 1200 lb instead of the 2400 lb at the incoming lines. ( I tried to upload an MP4 video but apparently the Forum does not accept that file extension)

    So now I am thinking I will reverse those two piston sleeves that I was unsure about the sleeve position and see if that kicks up the 1200 lb pressure to 2400 lb?
     
  13. TVA

    TVA Senior Member

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    Does it bypasses or restricts?
     
  14. TVA

    TVA Senior Member

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    Interesting that it drops pressure in half! Flow divider?!
     
  15. Ronray

    Ronray Well-Known Member

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    I don't know if it bypasses or restricts. Since I have one of the outlets on the pressure gauge and capped off, and the other three Outlets capped off, I'm wondering if it's possible that part of the hydraulic flow is going back through one of the two Inlet beefy hoses that is not engaged? And if so, where would that fluid go if the proportional valve was already directing fluid to the other valve block Inlet line?
     
  16. TVA

    TVA Senior Member

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    Damaged counterbalance valve, not fully seated shuttle valve will bypass to return side, how to check it - I already posted that. Still very interesting that it cuts pressure in half!
     
  17. Ronray

    Ronray Well-Known Member

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    The schematic diagram would indicate a steel ball in the shuttle valve, but there was no steel ball in my shuttle valve, just a small 16th of an inch drilled hole connecting the two Inlet ports and the shift cylinder and parking brake circuits. I don't see where you gave instructions on checking the shuttle valve?

    That being said, I'm thinking of checking the pressure to the outlet big beefy lines after removing internal parts from the valve block one by one, and so I am thinking about starting with removing the flow divider valve completely and see what that does to the exit pressure?
     
  18. TVA

    TVA Senior Member

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    So, because there’s no ball two inlet ports and speed shift/park break passages just open to each other full time?!
    I remember Grove menlift had that thing right underneath the 1/4 fitting, tiny little ball? You would have to shine your flashlight to see it! It was crimped over after it was dropped in there. So if you loos it you would have to re machine or replace the block! If that block not there - that is the problem!
     
  19. TVA

    TVA Senior Member

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    Removing flow divider or counterbalance valves will open up cross port leakage even more!
     
  20. Ronray

    Ronray Well-Known Member

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    you mean missing ball, not block, right?