Hydraulic Top Link Drawbacks

[Baby Grand]

Try heating it...

Heh-heh - yes!
Or even reduce the ambient pressure enough to approach the vapor pressure - especially if there's any water entrained in the oil.

 

[JWR]

Try heating it...

Oh good grief you guys ! Vapor pressure ... ! Irrelevant. Both water and hydraulic oil (and brake fluid) are for any practical purpose incompressible fluids. That is why hydraulic oil is used for hydraulic applications. Any expansion or contraction is negligible. Back to the original topic -- just take the hyd top link and hang a good heavy attachment on it , like a big bush hog or for that matter the snow blower, detach the hoses, and watch it for a few days to see if it drifts. (I would, but I have other things on the tractor I can't readily move at the moment. ) It may be hard to pull the hoses with a lot of pressure on them (?)

 

[MtnViewRanch]

Oh good grief you guys ! Vapor pressure ... ! Irrelevant. Both water and hydraulic oil (and brake fluid) are for any practical purpose incompressible fluids. That is why hydraulic oil is used for hydraulic applications. Any expansion or contraction is negligible. Back to the original topic -- just take the hyd top link and hang a good heavy attachment on it , like a big bush hog or for that matter the snow blower, detach the hoses, and watch it for a few days to see if it drifts. (I would, but I have other things on the tractor I can't readily move at the moment. ) It may be hard to pull the hoses with a lot of pressure on them (?)

Why would there be any pressure on them? Unplug them with the implement on the ground and then raise the implement to put the pressure on the unit.

 

[bumperm]

Try heating it...

Yum! French Fries!!

bumper

 

[JWR]

Why would there be any pressure on them? Unplug them with the implement on the ground and then raise the implement to put the pressure on the unit.

True. You're right. The tractor 3pt lift arms/hydraulics will do the lifting, not the top link. My goof. Anyway, just do that and see if the thing drifts.

 

[breadtrk]

So, if I understand this correctly, my backhoe should stay in perfect position when unhooked to hook it back up again? That thing relaxes and uncurls in a matter of hours after I unhook it. It is Brand new, no more that 20 hours on it total.

 

[Kenneth in Texas]

only drawback i see is PRICE. I asked my local kubota dealer today how much for him to add one on my tractor, $1000 he said. Surely it cant be that much can it? Isnt this something i can do myself?

 

[bumperm]

So, if I understand this correctly, my backhoe should stay in perfect position when unhooked to hook it back up again? That thing relaxes and uncurls in a matter of hours after I unhook it. It is Brand new, no more that 20 hours on it total.

Well, no, it's not the same situation. Even though a typically "power beyond" back hoe's hydraulic system is connected to the tractor via two self-sealing quick disconnects, it's a lot more complex than a hydraulic cylinder. Consider that each of the hoe's cylinders is controlled by a spool valve, and that spool valve is not disconnected from its associated cylinder when the hoe is disconnected from the tractor. Any residual weight or loading on a hoe's cylinder will result in a pressure differential across is spool valve, and that valve most often has some creep.

As an aside, I store my BH77 hoe on a rolling cradle. I use a nylon ratchet strap to hold up the stabilizers, then, before the hoe is removed from the tractor which is shut down, I move all the hoe's controls to remove any pressure on the hoes cylinders. Only then do I disconnect the hoe. This procedure makes it much easier to hook up the hoe next time, as there won't be any pressure on the quick disconnects making it hard to connect them.

 

[Gordon Gould]

Pretty interesting info here. Some I have to read a couple times - deep stuff.
To me there are no real drawbacks. They are adjustable !! So pay attention and adjust them if they drift a little.
To me it is money well spent for a TnT system.

 

[Threepoint]

only drawback i see is PRICE. I asked my local kubota dealer today how much for him to add one on my tractor, $1000 he said. Surely it cant be that much can it? Isnt this something i can do myself?

Kenneth, that sounds high to me, even for a dealer using Kubota factory parts. But there's a lot more to it than just ordering a hydraulic toplink cylinder, hoses and fittings, which you could probably do for around $200 - $250. I'm assuming your tractor does not already have a rear remote valve setup installed, so you'll need that (dual rear remotes if you think you also may want to add a hydraulic sidelink in the future). Plus dealer labor. I would have guessed around $700 at the dealer, but clearly I'd have been wrong! Sure, you could do it yourself if you're handy and get the right guidance on parts and sizing. Lot's of folks on this board have done it. Also, if you were to decide you do not need or want a check valve on the cylinder, Brian at FiteRite Hydraulics (and an active TBNnr, MtnViewRanch) can get you everything you need at a fair price, plus talk you through it all. For a toplink hydraulic cylinder with a check valve, you'd need to source elsewhere, as Brian does not offer them at this time. (The need or not for a check valve is discussed in numerous threads on TBN).