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  1. #1
    New Member
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    Sep 2012
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    Brush Prairie, WA
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    Kubota

    Default Hydraulic Pressure Relief Valve Question

    Folks,

    I know we are mostly about tractors. I don't have a question about my kubota, but do have one about hydraulics. Because you guys seem to understand the topic I am coming to you.

    I have a new custom built, electric hydraulic press and need advice. The press has a 2 hp motor and a 5" cylinder with a 16" stroke. I need to install some type of "valve" or "device" to be able to dial in a specific, and in my case, lower, gauge pressure. I am familiar with calculating force. That is not the problem. I would like to put in a device that I could set to a specific pressure that would shut off the motor, or bypass the hydraulic lines at a specific, preset pressure. I would like repeatable pressing within small limits. Advice is welcomed on how this can be accomplished. Thanks to any who reply.

    Admin, if this is inappropriate for this forum, please delete and accept my apology.

    Ric

  2. #2
    Silver Member birddog0304's Avatar
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    Apr 2012
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    Northeast TN
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    John Deere/Massey Ferguson/Bobcat

    Default

    Welcome Ric. Lots of very intelligent folks on tbn. Are you wanting a single preset pressure, multiple presets or something adjustable?
    I would think an adjustable relief valve on the high pressure side emptying in to return line or reservoir along with a pressure gauge teed in to the high pressure side would allow you to accomplish your goal at a basic level.
    I welcome any additions or corrections to my thought process.

  3. #3
    Veteran Member SSdoxie's Avatar
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    Jun 2010
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    1,997
    Location
    Cumberland Plateau, TN
    Tractor
    Bobcat CT225

    Default Re: Hydraulic Pressure Relief Valve Question

    I agree with Birdog, an adjustable relief dumping to tank. Locate the valve and guage close to the inlet to cylinder for most accurate reading then if you have if you have some commonly used pressure setting you can put different marks the guage face to adjust/set pressure without going back to the pressure to force calculations.
    Dennis

    CT225 w/7TL QA FEL, 60"tooth dirt bucket, 68" smooth bucket, Pallet Forks, Bale Spear. Hydrualic top llin, QH, 48 RC, 60" tiller, Angle blade, Landscape rake, Carry-all, Post hole auger.

  4. #4
    Elite Member
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    Sep 2008
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    3,178
    Location
    NE USA
    Tractor
    JD LA115, WH 244, WH 525 hydro-pops,Original Troy Built Horse 8 HP

    Default Re: Hydraulic Pressure Relief Valve Question

    Quote Originally Posted by rwunn View Post
    Folks,

    I know we are mostly about tractors. I don't have a question about my kubota, but do have one about hydraulics. Because you guys seem to understand the topic I am coming to you.

    I have a new custom built, electric hydraulic press and need advice. The press has a 2 hp motor and a 5" cylinder with a 16" stroke. I need to install some type of "valve" or "device" to be able to dial in a specific, and in my case, lower, gauge pressure. I am familiar with calculating force. That is not the problem. I would like to put in a device that I could set to a specific pressure that would shut off the motor, or bypass the hydraulic lines at a specific, preset pressure. I would like repeatable pressing within small limits. Advice is welcomed on how this can be accomplished. Thanks to any who reply.

    Admin, if this is inappropriate for this forum, please delete and accept my apology.

    Ric


    You should contact the folks at Mentor hydraulics in Mentor, Ohio
    and you can obtain the right valve assemble with the relief in one unit
    with both pressure and flow control.

  5. #5
    Super Star Member J_J's Avatar
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    Sep 2003
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    16,349
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    JACKSONVILLE, FL
    Tractor
    Power-Trac 1445, KUBOTA B-9200HST

    Default Re: Hydraulic Pressure Relief Valve Question

    The relief has to be caused by a hard stop to stop at a certain distance.

    If the item you are bending, is soft, then the relief will not be met
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

  6. #6
    Gold Member
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    May 2012
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    Gidgiegannup Springs, Western Australia
    Tractor
    Massey Ferguson 148 .Chamberlain Super 70. Caterpillar D4. Chamberlain 354 FEL.Toro 268 rideon kubota L2002fel

    Default Re: Hydraulic Pressure Relief Valve Question

    G,Day j-j.
    Why ?????????????.
    Hutch.

  7. #7
    Super Star Member J_J's Avatar
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    JACKSONVILLE, FL
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    Power-Trac 1445, KUBOTA B-9200HST

    Default Re: Hydraulic Pressure Relief Valve Question

    Why what,

    You don't always need relief pressure to shape and bend parts.

    If you allow the cyl to reach relief pressure, it may go past your intended stop.

    I believe you need a physical stop on the cyl to form the part correctly.

    If you only intend to bend, then there is room for error. You bend until the shape is made. You may have to bend past the angle to get the correct fitting. For instance, you may have to go 95 degrees
    to get the 90 due to spring back.
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

  8. #8
    Gold Member
    Join Date
    May 2012
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    293
    Location
    Gidgiegannup Springs, Western Australia
    Tractor
    Massey Ferguson 148 .Chamberlain Super 70. Caterpillar D4. Chamberlain 354 FEL.Toro 268 rideon kubota L2002fel

    Default Re: Hydraulic Pressure Relief Valve Question

    G,day jj.
    If the relief valve was set at the correct pressure to give the required result the ram would stop at the same point everytime,the machine is custom made I would not think it would be made so much overspec that it could not be controlled by relief pressure.
    Anyway a more accurate result would be achieved by either installing an adjustable trip stop and or an auto return solenoid,also depending on what is being done adjust the relief valve pressure to lower the operating pressure no need to be running at max pressure with this ram size and a supply pressure of say 2000 psi it would be possible to exert a force in excess of forty tons at the ram end.
    Thats all .
    Happy Days.
    Hutch.

  9. #9

    Default Re: Hydraulic Pressure Relief Valve Question

    I am not an expert on presses by any means, but I do not believe that they are normally pressure controlled. The ones I am familiar with actually stroke the same amount every time, but the lower form is raised or lowered to control the minimum distance between the dies. Like JJ says if you rely on pressure you will get inconsistant results as your raw material changes. Each batch will vary a little in temper, thickness, etc.

    ISZ

  10. #10
    Elite Member wdchyd's Avatar
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    2,675
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    Hooksett, NH
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    Kubota B2320

    Default Re: Hydraulic Pressure Relief Valve Question

    I've seen it done by using a series of microswitches....an adjustable on the extend and a fixed on the retract (home position)......but this would usually be accomplished by using soleniod control valves to limit stroke, not manual valves.......
    2010 Kubota B2320 FEL & BH65
    If it ain't fixed don't broke it!

    http://www.tractorbynet.com/content/...-month-wdchyd/

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