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  1. #1
    Platinum Member
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    Boerne, Texas
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    Kubota M9000

    Default Longer Top Link or Longer 3pt Tractor Bracket

    I added PECS to my M9000 and love it, problem is my Hyd Top Link is to short now. If you have two choices lengthen your HTL by having a new cylinder made 6" longer with a 1-1/2" ram so its heavier duty then the current one which is a 15-3/4" cylinder with a 1-1/4" ram at a cost of $200 or Have a metal shop cut two triangles essentially 8" triangles cut out of 3/4" Plate and bolt them to the current 3pt bracket using all 3 holes on the tractor to attach them and one larger hole to accomodate the 3pt HTL at a cost of $100. Which would you opt for? I'm kinda leaning towards the new cylinder and beefing it up to better handle my task then to bolt on the metal and extend my 3pt tractor toplink bracket. If anyone else has any great ideas I'm all ears, Greg_G mentioned some type of flexible top links in a different thread but it seems I'd have to rig one up as I haven't found anyone that sells them commercially or this would seem like good a option as well.
    Steve

  2. #2
    Super Member 3RRL's Avatar
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    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    Steve,
    I'd go with the new cylinder so you can still use the 3 holes on the tractor. Some cylinders offer different rod diameters in the same stroke and body size. In otherwords, a 3" cylinder with a 10" stroke may be available with a 1-", 1-". 1-3/4" rod or larger diameter. I would go with the largest diameter rod in the cylinder size you choose for strength.
    Rob-
    ...The Older I get...the Better I Used to be...
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  3. #3
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    northfield connecticut
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    gradall g3r excavator, kawasaki mule 2500,ford 8000,and a 1936 caterpillar road grader

    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    dont forget the larger the rod the less force the cylinder will have pulling, which is the direction the force usualy is on a hydralic top link
    Kawasaki Mule 2500,Ford 8000,Caterpillar road grader,gradall g3r excavator,JD210c

  4. #4
    Platinum Member
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    Oct 2004
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    Boerne, Texas
    Tractor
    Kubota M9000

    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    markct, I was not aware of that not that it should effect my particular use since I'm using a M9000 (90hp) and cat 1 implements so most are light in comparison to cat 2 or 3. Most of my use is ground engaging stuff though so it does concern me, plowing, discing, BB etc. Are you sure that this info is correct I'm looking for bullit proof not fast but I'd hate to lose the ability to pick something up because I went with a 1.5" ram instead of a 1.25"
    Steve

  5. #5
    Veteran Member
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    May 2002
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    Warrenton MO
    Tractor
    JD4100 Hydro

    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    Quote Originally Posted by stevenf
    Are you sure that this info is correct I'm looking for bullit proof not fast but I'd hate to lose the ability to pick something up because I went with a 1.5" ram instead of a 1.25"
    Steve
    The pulling or pushing force is determined by hydraulic pressure in PSI times the area, in square inches, of the piston in the cylinder. When the cylinder is pulling, the area of the piston is reduced by the area of the rod. When the cylinder is pushing, the full pistion area is available for the fluid to act upon.

    An extreme example would be comparing a 2" dia. cylinder with a 1/2" rod to a 2" dia. cylinder with a 1 1/2" rod. Don't even need to do any math to see that the second example has a lot less area for the fluid to act against when pulling that rod.

  6. #6
    Super Member 3RRL's Avatar
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    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    ...dont forget the larger the rod the less force the cylinder will have pulling, ...
    I agree with this but I don't think it will make enough difference to worry about in general use. Look at your loader cylinders for example. They are REALLY subject to direct forces. The top link is different as it has help from the lower arms, therefore don't have nearly the direct forces as the loader cylinders do. Using 3PT attachments, the lower arms do most of the "pulling" and the top link is primarily for positioning and stability. Plus if you put a dual operated checkvalve on the cylinder it's going nowhere. Tilting the implement such as a boxblade should be easily done even with a wimpy cylinder because the implement will "revolve" so to speak, around the lower lift pins. Holding in that position can be accomplished with the check valve. I'd want a large diameter rod to reduce rod flex or possible bending of the top link.

    ...which is the direction the force usualy is on a hydralic top link...
    I disagree for the following reasons. The implements are secured to the lower lift arms via lift pins and also to the top link cylinder. When the implement is raised off the ground and manipulated (tilted) by the top link cylinder, that's the only time it pulls the implement, trying to rotate around the lower lift pins. Pushing the implement down (tilting backwards) is easy because it's weight helps. Pulling the implement (rotating it up) requires the cylinder to retract and as long as the cylinder has enough rating, more than the weight of the implement, it's going to do that. Each cylinder will have a chart of how much it can pull or push and I bet none of your implements will exceed the force exerted by the cylinder pulling or pushing. (Unless you get a super dinky one of course)

    So under use, all "towable" implements like the brush hog, a trailer, etc. will subject the cylinder to this. But the lower arms do most of the pulling. Now, ground engaging implements like boxblades and rear blades are different. Once the implement engages the ground, the tractor is going forward and the boxblade, for example, is giving resistance from use of it's scarifiers or blade. The resulting force will be straight back or even a rotational vector force caused by when the implements wants to rotate upwards around the lower lift pins. Guess what force the top link sees when that happens? That's right...it wants to compress. That means it's working against the "non rod" side which has the greater surface area. And if you had a check valve, it shoud not budge regardless. An example would be to hook up your boxblade to the lower arms only, without the top link attached. When you hit a rock or stump, I bet it wants to flip up? (rotate around the lift pins)? I think plows will tend to be dragged equally by the lower lift pins and top link except the occasional bump which will try to raise it. Another example to show the force go against the lift arms is when bulldozing with the boxblade in reverse. That will try to stretch the top link cylinder open because the blade will try to "fold" under the lift arms. That is why you bend lift arms, or in my case I've bent my side links doing that.

    If the implement has resistance from above, like when you attach a chain to the top of the box blade. the opposite is true, and now the force is pushing against the "rod side" or trying to stretch the cylinder open. This is also seen when pulling something directly by the top link, which I would not do. And also when using a 3pt backhoe. Digging the bucket in, trying to stretch it open, will exert pressure on the rod side. But it is better to have a subframe anyway.

    Please keep in mind that these are my opinions derived from my experiences and it doesn't necessarily mean I'm correct. I'd like to hear what others have to say what forces the (hydraulic) top link sees?
    Thanks,
    Rob-
    ...The Older I get...the Better I Used to be...
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  7. #7
    Platinum Member
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    gradall g3r excavator, kawasaki mule 2500,ford 8000,and a 1936 caterpillar road grader

    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    if ya use an implement like a boom pole or pallet forks it sure is pulling on the top link
    Kawasaki Mule 2500,Ford 8000,Caterpillar road grader,gradall g3r excavator,JD210c

  8. #8
    Super Member 3RRL's Avatar
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    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    Quote Originally Posted by markct
    if ya use an implement like a boom pole or pallet forks it sure is pulling on the top link
    Right, no doubt about it.
    Just make sure the cylinder (with larger rod) still has enough force to overcome that "pull". IMO, it would need to be what your 3pt lift is rated for....maybe more so it is not the "weak link" in the system. Surplus Center lists the "push/pull" on each cylinder so you can pick what you need. They have a wide variety. http://www.surpluscenter.com/hydraulic.asp
    Rob-
    ...The Older I get...the Better I Used to be...
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  9. #9
    Veteran Member daTeacha's Avatar
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    Funk, Ohio

    Default Re: Longer Top Link or Longer 3pt Tractor Bracket

    A whole different option which would avoid the debate about what the top link actually does in any given situation is to modify the implement. Rig, by whatever means will work, some way to relocate the top link attachement point. For example, you could weld on an pieces of appropriately drilled steel plate that would give you another hole for the pin forward, up, back, or anywhere in between. Instead of relocating the tractor end of the cylinder, relocate the implement end. You'd need to watch the angles at which things work, of course, but that's more or less the reason for the hydraulic top link in the first place.
    Rich
    300 hours on the DX29, 850 on the JD 240 and too many to count on the Cadet
    Funk, Ohio

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