Haas Nitrogen/Hydraulic counterbalance top off.
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  1. #1
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    Default Haas Nitrogen/Hydraulic counterbalance top off.

    Is there a right way to do this without catastrophe or losing hydraulic fluid?

    Currently the gauge reads 550 lbs. My machine says it requires 750 lbs.
    Have a tank with 1700 lbs of dry nitrogen. Borrowed a high pressure hose with a valve at the end.
    Do not have a high pressure regulator. (only a low 300lb one)
    But then again I haven't seen much usable information on whether a regulator is required.

    What to do?

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    Yes there is a proper way to do it. first I must ask do you have the correct hose ? if so, this is how you do it. first connect hose to dry nitrogen tank ( the big fitting end to the new dry nitrogen) tighten that end. next before you screw on the fitting on the Haas side , make sure the the little "T" in the middle of the fitting is backed out, as to not touch the pin in the fitting in the haas connector when it is installed and tightened. then tighten that fitting ( but do not touch the "T" at all!!!!) now slowly open the valve on the dry nitrogen tank ( not the haas side!!) the pressure of the dry nitrogen will at some point be greater than what's in the haas tank, and it will unseat its valve.you will hear the haas tank gargle and make noise. be careful to fill the haas tank slowly. when the pressure of the haas tank reaches 50 psi greater than the haas tank fill pressure number ( in your case 800 psi). turn off the dry nitrogen fill tank handle.now here is the tricky part. on the dry nitrogen thank ( the fill tank with the large fitting) loosen the fitting as fast as you can , while doing so on that same end pull the center part of the fitting sideways. this causes the release of the pressure rapidly. which slams the haas tank valve to seat it to keep it from leaking oil and also ensuring the valve from leaking. at that point remove hose from both sides. the only time the "T " handle on the haas side is used . is when you need to drain the oil from the tank ( which is almost never) or when you fill the tank with oil ( when tank is removed and turned right side up)

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    Not sure you should try if you don't have the exact equipment and know how to use it. It has to flow SLOWLY!!!!!

    Be careful.

  4. #4
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    Just a thought after having to deal with this myself. The nitrogen reservoir is mounted upside down. When you refill, the nitrogen is intended to flow through to the bulk of the nitrogen in the tank. Ideally, the nitrogen never expands out of the confines of the tank... it is just used to pressurize the DTE25 hydraulic fluid in the remainder of the system. Where you tend to lose pressure is from the bottom of the cylinder. What you lose is the DTE25 fluid, not the nitrogen.

    And yet everyone tells you to fill the nitrogen. I do get that it is possible for the nitrogen to get entrained in the DTE fluid,and that it is quite possible for the entrained nitrogen to outgas/percolate through the worn bottom seal, but seeing haw everything looks wet at the bottom of the cylinder... yeah... kinda makes you think.

    If you keep on filling with nitrogen eventually I think you will mostly run out of hydraulic fluid.

    What I did was put about a two cups of DTE25 fluid in the port using a DeWalt grease gun. This was cake to do and actually the pressure went up maybe 50 psi (I have a VF3 and I need 1150 and it had dropped to maybe 850?) I then added the nitrogen to take it up to 1150.

    This grease gun idea was somewhere on this site in a previous lifetime.
    For me this worked like a charm. Your results may vary.

    In theory you should be able to calculate how much nitrogen is in the system via PV=nRT, where n is the amount of nitrogen (in moles). Find the pressure at top of stroke and bottom. Figure out the cylinder ID and get the volume. I haven't done this myself but I was willing to shoot from the hip.

    I did have a Haas tech in recently for another issue and he told me the counterbalance is not a terrible thing to replace. The instructions tell you to indicate it in, implying the positioning has to be precise, but the tech told me the body of the cylinder is held in place with worm gear clamps and common sense tells me those are not too precise. If I start losing pressure I will get the counterbalance kit for $1,695 and replace it myself. You definitely shouldn't replace just the cylinder as the contaminants from the worn out seal would probably show up in the tank, causing a new cylinder to wear out quickly.

    BTW, hose and fitting (Shrader high pressure strut coupler) can be found on Amazon and the fitting can work for both filling the DTE25 and nitrogen. This info is also elsewhere on this site.

    Um... when you refill the nitrogen, you use a Shrader strut coupler, connecting hose, and adapter to mate with your nitrogen tank. There is no regulator involved. You need to be sure there is enough nitrogen in your tank (I got mine filled just before doing this), and you need to open the valve on your supply tank slowly and turn it off when you hit the desired pressure.


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