Check valves

[BlacknTan]

Are check valves available to add in line to a hydraulic top link? How do mfgrs other than CCM stop their valves from leaking down?? There must be devices that could be added... No??

[kennyd]

Are check valves available to add in line to a hydraulic top link?

This was discussed YEARS ago by the late great Madreferee...and also by 3RRL.

There are DPOCV's available, but they are way bigger than what CCM has, and the pop-off pressure is not right for CUT use. Fact is the only game in town is what CCM gets from his secret source. BUT they will sell just the valves if you call them.

How do mfgrs other than CCM stop their valves from leaking down??

They don't...

[Wayne County Hose]

It's the style of valve being used which leak down. I can show you applications without dpocv's that absolutely do not leak down. Get the right high quality valve and they don't leak down. A valve seals by the same principals as a cylinder. It's all in the seal style and configuration. Most valves on your CUT's don't even have internal seals, this is why they leak down.

[kennyd]

Originally Posted by Wayne County Hose

It's the style of valve being used which leak down. I can show you applications without dpocv's that absolutely do not leak down. Get the right high quality valve and they don't leak down. A valve seals by the same principals as a cylinder. It's all in the seal style and configuration. Most valves on your CUT's don't even have internal seals, this is why they leak down.

Good point. The poppet style and pilot operated valves used in commercial equipment are great! That is why you see raised equipment at Bobcat and rental dealer for weeks on end...

[BlacknTan]

Could someone point me in the direction of a high quality cylinder that does not need a check valve to prevent bleed down??

PM if you feel the need..

[kennyd]

Originally Posted by BlacknTan

Could someone point me in the direction of a high quality cylinder that does not need a check valve to prevent bleed down??

PM if you feel the need..

As Andy said, its not necessarily the cylinder, but the spool valve that leaks and causes the cylinder to move. Why do you seem opposed to the CCM unit? It's certainly a proven system...

[MichiganIron]

DPOCV's are not that difficult to find at 600psi cracking pressures.

Whether they are necessary or not is a different discussion. OSHA requires "Mechanical Locking" on hydraulic lifting equipment. A top link for a box scraper, or other landscaping equipment, on the back of a home owner's compact tractor probably does not quite fall under the OSHA requirement. CCM may require them for liability reasons. That's business in America.

Practically, even with minor spool leak-down, you can easily control a hydraulic top link to do what you want without a DPOCV. They are a nice feature, but not a necessity for the homeowner looking for the usefulness of a hydraulic top link.

You can find the same DPOCV's at Baileynet.com if you want that feature on your top link.

What you really want to be careful of to have a useful top link is the retracted length. Many of the top links have retracted lengths in excess of 21", which is too long to be useful on many compact tractors. You want a link that has a "center" of travel that is about your normal top link length. That gives you the ability to angle your equipment with the most versatility. For most compacts, that puts the "center of travel" somewhere around 21". Make sure the cylinder will do what you need for it to do. A DPOCV can be added to any hydraulic top link. Just get the right length for your tractor.

[BlacknTan]

Originally Posted by kennyd

As Andy said, its not necessarily the cylinder, but the spool valve that leaks and causes the cylinder to move. Why do you seem opposed to the CCM unit? It's certainly a proven system...

kennyd,

I'm in no way opposed to the CCM units. And I agree that they're proven by all the folks that swear by them here.
I just like to have alternatives...

And, thanks to everyone for their responses.

[KML]

O.K. stupid question time....

Is there any other cylinder on a tractor with a check valve? I didn't think there were. Just seems odd to me that one would worry about the top link leaking down but not care that the 3pt lift cylinder does.

I'm getting ready to add a hyd top link to my 2210 and I'm really wondering what the concern is. I just don't see it. I'm sure I'm missing something.....

[bjcsc]

Originally Posted by KML

Is there any other cylinder on a tractor with a check valve?

Not that I have ever seen. As said twice so far, this has more to do with the valves than the cylinders. I'm working on adding TNT to my tractor and luckily my valves do not leak down and I won't need the check valves for the cylinders ...

As far as going without it, yeah I guess you could keep readjusting it but that defeats the purpose. Whenever you get resistance (e.g.BB) it will change right before it does what you wanted it to...