Help with inverting air over hydraulic jack to work upside down.
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  1. #1
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    Default Help with inverting air over hydraulic jack to work upside down.

    Hi all, I have two AC hydraulic 10/20 ton jacks the same style as shown on YouTube (how to repair your 65T air hydraulic jack. By AC Hydraulics) that were replaced in our workshop due to failing. I have one working again but it won’t be put back in service for lifting so I want to use it in a press.
    While I can cut the jack body apart to keep the oil reservoir in tact and upright and I can mount the motor up the right way I want to invert the ram for the press. The ram is fed oil through a gallery between the motor and ram which is located between the three bolts that join the two together. This will require drilling and taping the oil passage in the motor body and ram housing so a hydraulic hose can be fitted but I need to know if this will work or do I need to modify the the entry point of the oil into the hydraulic ram and the return line. If I can get this sorted it will be perfect for an air over hydraulic press rather than tossing them in the scrap bin. Please see the YT video listed above to see how the jack is constructed and what I am trying to do.
    Any help would be greatly appreciated. Thanks in advance, Stuart, Australia.🇦🇺

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    Look at the way Harbor Freight builds their 20 ton press. That configuration keeps the jack upright and eliminates the problem of trying to operate a jack inverted.

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    Quote Originally Posted by Illinoyance View Post
    Look at the way Harbor Freight builds their 20 ton press. That configuration keeps the jack upright and eliminates the problem of trying to operate a jack inverted.
    Hi Illinoyance, I used to have a press that worked that way and I hate them. I find that there is to much play in the ram for me and what I do. I have a 20Ton press with a modified jack that works upside down but the air over hydraulic would be a lot more convenient. I tried the ram inverted today using air and it worked well so I’m thinking I will just do it and see. Thanks Stuart.

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    You could just take out the rubber filling plug, braze on a barb.

    Hose to a second reservoir up high (soup can is what I used).

    flood the system is what you doo.

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    Hee hee... the problem Scrounge is having, is that he's Down Under... and gravity works backwards down there ;-)

    Scrounge... If Doug's note doesn't make sense... what he's saying, is that the problem of inverting isn't so much having the oil where you need it, it's about getting the air out of the pump's draw-path. By putting a fitting on the filler, and hosing it up to an elevated reservoir, you now regain a closed system with the airspace higher up.

    It might leak a little, but it'll work... it'll inhibit rust.
    You may need to bleed air out of the top (formerly bottom)... or better yet, drill and tap a hole for a small fitting, and run it up to the reservoir.

    Doug says Soup Can, I suggest an old hand-held MAPP or Propane bottle that's already been discharged of it's contents... fit a simple cap to it, but give it an appropriate vent, so your pump seals don't get blown. You ARE a scrounge, yes?


    The Bible is WRONG... PLUMBING is the ROOT of ALL EVIL.

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    Thanks Digger Doug and DaveKamp, this is no simple bottle jack with an air motor connected to it. I already have manual bottle jack working quite well upside down. That’s why I left a link to the YT video. I think if you have a quick look at the video you will see this unit is made quite differently.
    The biggest problem with being down under is that I have to turn the screen upside down to read it. ��������

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    When you get done with figuring out this little exercise you will end up with a 1/2 ton press at best.

    Those little pump bodies generate nearly 10k psi. Your shop air might get up to 120 psi.

    Do the math on the jack piston area.

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    Not quite sure what you’re talking about. Its air over hydraulic so the air drives the hydraulic pump. Once I had it working again it lifted my truck no problem using 120psi.

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    Quote Originally Posted by Scrounga2 View Post
    Thanks Digger Doug and DaveKamp, this is no simple bottle jack with an air motor connected to it. I already have manual bottle jack working quite well upside down. That’s why I left a link to the YT video. I think if you have a quick look at the video you will see this unit is made quite differently.
    The biggest problem with being down under is that I have to turn the screen upside down to read it. ��������
    I don't see a linky.
    If you have a super specialized rarified jack, how can any of us help you ?

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    e45c2431-e59f-4b68-8481-06cc16fef453.jpg
    Here is a picture of a similar jack. I admit it would have been better to add this to my original post.
    There was no link in my post but I did have this sentence near the bottom of the post saying:
    Please see the YT video listed above to see how the jack is constructed and what I am trying to do.
    So no, it’s not some rarified jack but it’s not your average bottle jack with an air motor add either.
    hope this helps. Cheers Stuart.

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    Quote Originally Posted by Scrounga2 View Post
    The biggest problem with being down under is that I have to turn the screen upside down to read it. ��������
    :-D Dangit, I HATE it when that happens... Do keep your dustpan and broom handy, so you can gather up and properly recycle all those bits that fall out. We keep wasting so many, that the binary world is desperately short of ones and zeros...

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    Okay, Stu- I took a look at the video... at 4:49, you see the hydraulic power unit removed from the base, and on that base is a single O-ring with three holes. THAT is the key.

    You need two blocks of metal... one to fit over those three holes, with passages centered in the O-ring, drilled through to the other side, and on the other side, drill and tap for threading fittings for high-pressure plumbing between the two, and then mount the pump remote from the cylinder.

    In it's native orientation, the pump is barely above the bottom of the cylinder. The low-pressure plastic line is a displacement/return. You'll need to plumb the displacement return line UP to a reservoir, and plug the corresponding power unit port... use a high-mounted T, so that entrained air can find it's way up to your reservoir.

    Won't take much reservoir... a beaker would be more than enough, I'm certain... just mount it above everything else, and give it a vent of some sort.

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    Hey Dave, that makes sense but I’ll read it a couple of time to make sure it sinks in. “I’m not a smart man”. I have cut up the frame of the jack so I can use the original reservoir. Less work than making a new one. One thing I’m not sure about is the return line. Do you mean the return line from the actual jack? It has a small low pressure return mounted high up on the jack when the jack is in its normal orientation which becomes low when the jack is inverted?
    I found a threaded port on the jack body I can use to attach a high pressure hose so I only need to modify the pump motor. I like your idea of making a block for the pump motor and I will use that. I was going to drill and tap the original hole but your idea is better. Can’t do much at the moment as we have large bush fires here so we are busy getting ready incase they swing our way. I live in Canberra, the nation’s capital, and the fires are less than 50km away. Tomorrow it’s forecast to be 42deg C with strong winds. We used to think we’d be safe in a bush fire but back in 2003 we had over 500 homes destroyed so now people take it seriously. The Navy is evacuating some towns by sea as the roads are on fire and the airforce is supplying all sorts of aircraft like transport planes, Chinook helicopters and black hawks for their night vision and army with their equipment are involved as well. We are also getting fire fighters from New Zealand, America and Canada so it’s pretty bad at the moment.
    Sorry got off topic. Thanks for your help and ideas. Cheers Stuart.
    Ps I think any stray binary will be a bit to crispy to use again.


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