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Simple Hydraulic circuits

  1. Aug 6, 2012 #1
    Hey all,

    I never studied hydraulic circuits but I needed to design/make a hydraulic system for some research equipment. The system (in the attached schematic) has been hooked up and used for 6 months or so. However, I think we went the hard way on with getting the air out (we had no idea what we were doing.

    Anyways, my question is can I put a bleed line on this system to help with getting the air out. Never mind if the symbols are drawn incorrectly as this is pretty much just a general schematic for what we have done. If it helps, the max pressure we will ever run in the system is about 2000 psi.

    Thanks for the help!


    Attached Files:

  2. jcsd
  3. Aug 6, 2012 #2
    A system should have a place where air naturally accumulates. If the cylinder is mounted vertically, that would be the place. Put the air bleed there. If in a simple system you have no such point, then don't worry about it. The air will wash back to tank and automatically purge itself from the system.
    Last edited: Aug 6, 2012
  4. Aug 6, 2012 #3
    Great. Thank you. I will try what you said.
  5. Aug 8, 2012 #4


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    The only way I have ever had to bleed a hydraulic injection moulding machine circuit is by cycling it. Over a few hundred cycles it does makes its way out. They all have an open tank as in your diagram.

    Take care though - hydraulic oil compresses the air until stiction is suddenly overcome and then the cylinders jump - too far sometimes! That much air is usually gone after a dozen cycles or so and it behaves better after that.
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