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  • hydraulic jack orientation

    Probably a stupid question, but can a typical hydraulic jack be used upside down? I'm going to say no, but maybe there's a way to modify one such that it can- I'm thinking to add a reservoir using the fill hole as a port and purging all air from the housing. The reservoir would sit higher than the upside-down jack and would be vented so the fluid can rise and fall in it, never falling below the level of the jack.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    Yes, a jack can be modified to work upside-down. You can either add an external reservoir, like you mentioned, or add a "straw" to the pump feed.

    I used the straw method for my press. http://bbs.homeshopmachinist.net/thr...-Press-Project It works well, especially with some thicker oil and with the reservoir vented to atmosphere.

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    • #3
      Originally posted by darryl View Post
      Probably a stupid question, but can a typical hydraulic jack be used upside down? I'm going to say no, but maybe there's a way to modify one such that it can- I'm thinking to add a reservoir using the fill hole as a port and purging all air from the housing. The reservoir would sit higher than the upside-down jack and would be vented so the fluid can rise and fall in it, never falling below the level of the jack.
      When I was an apprentice I was told by the journeyman "there are no stupid questions, only stupid people." But that is a good question. No, as built bottle jacks don't work upside down. But porta-powers are cheap at princess auto.

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      • #4
        Yes, just disassemble the jack, find the pump inlet hole in the base and locktite in a piece of pipe that extends to the other end of the housing. Assemble, fill with oil, purge air and use it.
        Amount of experience is in direct proportion to the value of broken equipment.

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        • #5
          I like the pipe idea- does seem like it would solve the problem. Not sure if I can get it apart though- need bigger vise, bigger wrenches, bigger f'n hammer The basic premise is to keep the inlet side of the pump full of fluid, so at least I know of two ways to do it now, thanks. I left the jack upside down for a while today to see if it would leak fluid, but that seems ok, so I carried on with the design and fabrication of the press frame.

          I'm going to arrange a foot pedal to do the pumping, which means some linkage back to the top, a link down to catch the pump rod, a pull cable, and a pivoting foot pedal. I'd like to get the geometry right so a reasonable amount of foot pressure will apply about the same force to the piston rod as a heavy hand pressure would using the supplied handle and linkage. I'm taking a wild guess to say that foot pressure would be about double what hand pressure would be, considering what my body weighs and how much force I could apply by hand vs putting much of my weight on a pedal.

          One other way I thought to figure this is to determine the ratio of pump rod diameter to shaft diameter, factor in the 6 tons that this jack is good for, then use a figure of half my body weight as the actuating force. I'll measure the stroke of the pump rod and the stroke of the foot pedal at the point where the cable attaches to it, and see if I find a happy medium.

          By the way, the 6 tons is pretty wimpy compared to what some of you have built, but I think it will be lots for almost anything I'd be doing in my shop. I can always upgrade to a 12T jack later if I want to. The frame will be good for it.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            I've done it without dismantling. Use the vent hole to connect a pipe to an higher external container and purge all the air from inside the jack's reservoir.
            Helder Ferreira
            Setubal, Portugal

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            • #7
              Now I'm wondering how well peened the threaded stub is- am I likely to be able to grip the piston to prevent it from turning, then twist the stub out? Or- I was thinking I could thread it out as far as it goes, then cut it off close without damaging the end of the piston. Then turn the captive part back down to leave some threads free for the stub to go back in. I'd like to be able to thread in a few different 'push posts'. One would be a solid rod, one would be a tube- others could be mounting arbors for specialty punches or whatever. And it wouldn't hurt to be able to secure a plate to the end of the piston- this plate would hold the springs that would be needed to retract the piston.
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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              • #8
                Ok so you are probably make a hydraulic press.
                If I have made an improper assumption, please
                correct me. Using an upside down bottle jack
                upside down in a press adds to the stack of column
                loaded length. This makes for an unstable press.
                Yes they sell them new made this way, and they
                are shlt. It is a bad design. Trash the jack idea
                and get a hydraulic cylinder. Mount it so the body
                is in tension, mounted at the nose. This way the
                cylinder is not part of the column stack. It is in
                tension, not compression. Press design 101.

                --Doozer
                DZER

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                • #9
                  mr doozer you are exactly correct.
                  I find I use my large, American made vice most often for a home shop press altho I have a 40t air over hydraulic if things are to large or tight.
                  besides, foot powering a hydraulic hand jack would make your leg really tired really quick.
                  a cheap horror freight porter power set would be a fairly cheap power supply for your press, they come with extensions that snap on and off, or if your serious about power, a ten ton OTC would be even better. . .

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                  • #10
                    Darryl, you wrote "factor in the 6 tons this jack is good for". If that jack is an inexpensive import rated at 6 tons, that may be a little optimistic. I once put a so-called 6 ton jack under a lead ballast keel weighing about 5500 pounds. The jack was nearer one end and would not have been lifting the entire weight. After putting as much stress on the jack as I considered reasonable, I went for a 20 ton jack.

                    I wouldn't seriously consider lifting a critical 3 ton load with a cheap "6 ton jack", and certainly not with the jack a foot in front of my face.

                    I rather suspect the rating for these jacks is the point where something fails catastrophically.
                    Last edited by cameron; 02-04-2014, 10:24 AM.

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                    • #11
                      You should also consider the force which needs to be applied to the jack handle. I regularly advise handymen jacking up basement beams where the load is about 6 to 8,000 pounds to use a low profile 20 ton jack so that they do not destabilize things with the amount of force they might have to put on the jack handle.
                      "Patriotism is the last refuge of a scoundrel"

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                      • #12
                        Doozer, could you elaborate on how the cylinder is installed please.
                        I am not seeing what you are talking about.
                        John Burchett
                        in Byng OK

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                        • #13
                          Originally posted by kc5ezc View Post
                          Doozer, could you elaborate on how the cylinder is installed please.
                          I am not seeing what you are talking about.

                          See in the ABOVE pic how the cylinder is mounted to it's nose
                          and any force applied makes the cylinder "get straight" within
                          the press frame? This is what you want. It is not part of the
                          column buckling equasion.


                          See in the ABOVE pic how the jack is below the press frame?
                          It is mounted by it's base, not it's nose. Therefore the jack
                          itself is in compression, and is deffinately part of the column
                          load equasion. Bad thing. Any force vector sideways can make
                          the press shoot parts out sideways.

                          --Doozer
                          DZER

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                          • #14
                            That picture of the 20 ton hydraulic shop press is meant to be a joke, right?

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                            • #15
                              Originally posted by cameron View Post
                              That picture of the 20 ton hydraulic shop press is meant to be a joke, right?
                              I don't think so, why would You ask?
                              All You have to do is apply the "dog years" formula to it.......ya know, 7 harbar frite tons =1 true ton.

                              Steve

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