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  1. #1
    Platinum Member westbrooklawn's Avatar
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    Default Closed System hydraulic top link

    Take a look at the video at the url listed below. It is a long video (8 min plus), but near the end it shows a closed system hydraulic setup for a top link. The concept looks great, and it doesn't appear to be too complicated. Has anyone built anything like this?

    Comments and thoughts from the expert fabricators on here? MadReferee... it looks like something you could fab together pretty quickly and then provide plans to the rest of us... [img]/forums/images/graemlins/wink.gif[/img].
    http://www.jiffyhitchsystems.com/

  2. #2
    Elite Member
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    Default Re: Closed System hydraulic top link

    I have seen that video before, about 2 years ago. It would be fairly easy to copy the Jiffy Hitch, IF I had a chance to take a good look at one first. Since I don't have one, nor do I know anybody that does, and the fact that I don't need one, why bother. I have 3 other projects on the drawing board right now including a soil pulverizer that I have the steel for, just no time to start them.

    BTW, the hydraulic top link with the self-contained fluid canister is used with a single acting cylinder. If you notice in the video they say you have to release the implement in order to retract the cylinder. That doesn't allow for on the fly adjustments in both directions. Quaint but not very realistic when you use a box blade in real time.

  3. #3
    Platinum Member westbrooklawn's Avatar
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    Default Re: Closed System hydraulic top link

    Mad-

    Take another look at the video... it shows how to retract the cylinder by letting the implement down, and pulling slowly forward... the weight of the implement then forces the cylinder to retract.

    I agree it isn't truly "on the fly", but it sure would beat manually adjusting the top link. It sure isn't any where near as nice as a hydraulic powered top link, but the cost would be very attractive when compared to the cost of adding rear remotes, valves, double acting cylinder, etc.

    I think I will try to fab one up and see how it might work (like you, I need another project like I need a hole in the head!!). It may be some time before I actually get into it, but I will post results.

    Also, couldn't you use a double acting cylinder with the closed loop full of fluid, and then just let the fluid flow through a valve from one end of the cylinder to the other? In other words a hose from one end of the cylinder to a simple shut off valve, then another hose from the other side of the valve to the other end of the cylinder, and then fill the system with fluid. With the valve open the ram would be free to move, and fluid would simply flow from one end of the cylinder to the other. With the valve closed, the ram would have to stay in the position it is in when the valve closes. Is my logic off base on this idea?

  4. #4
    Veteran Member jimgerken's Avatar
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    Default Re: Closed System hydraulic top link

    The resevoir is needed because the two sides of a hyd cylinder do not contain the same volume. One side has the rod inside it, so less oil. This difference in volume makes it necessary to have the res to catch the extra in one direction and supply the makeup oil when moving the other way. Hope that made sense. [img]/forums/images/graemlins/grin.gif[/img]

  5. #5
    Platinum Member westbrooklawn's Avatar
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    Default Re: Closed System hydraulic top link

    Jim -

    Thanks for shaking the cobwebs out of my brain... that answer is so obvious I can't believe I asked the original question.

    It would be pretty easy to calculate the required reservoir size by figuring the difference in volume between the rod fully extended verses fully retracted. All you would need to know was the cylinder length, rod diameter, and cylinder inside diameter.

    It still looks like a neat idea to me, and I think I will try to build one.

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