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   / Hyd top link #31  
Overszd I agree with you on a couple of points. First: A check valve will not fix a cylinder that has an internal bypass leak, it isn't going to happen. Second: I also agree that a check valve will hold a cylinder in place if the control valve on the tractor is leaking.

The fact still remains that check valves on cylinders do work the majority of the time. Have you ever heard of a TBN member that purchased a cylinder with a check valve say here that it didn't fix their leak-down problem? I know I haven't, yet I do hear praise for a cylinder equipped with a check valve.

It really doesn't matter to me or the next guy why they work or even how they work, as long as the implement stays where it's put.
 
   / Hyd top link #32  
By far, most leak downs occur because the control valve. That is why no one has reported a leak down with the check valve cylinders here on TBN as far as I know.
 
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  • Thread Starter
#33  
"So,,,,, if it's not the valve that is leaking, then it must be the cylinder rings. So,,, why would a check valve stop that??? A check valve only stops fluid movement outside of the cylinder"
Boy, I'm really paying attention now!
Ovrszd, this does make sense.Then forget about putting check valves on the cylinders and put them inline.

Waiting for Mad.
 
   / Hyd top link #34  
bones1 said:
"So,,,,, if it's not the valve that is leaking, then it must be the cylinder rings. So,,, why would a check valve stop that??? A check valve only stops fluid movement outside of the cylinder"
Boy, I'm really paying attention now!
Ovrszd, this does make sense.Then forget about putting check valves on the cylinders and put them inline.

Waiting for Mad.
Click to expand...

Bones check valves can indeed be built into the control valve. I believe Henro added a set to the valve arrangement that controls his top & tilt. Generally though most guys want the checks at the cylinders so that if a hose blows between the valve & cylinder the cylinder will still be locked in position.
 
   / Hyd top link #35  
PineRidge said:
Bones check valves can indeed be built into the control valve. I believe Henro added a set to the valve arrangement that controls his top & tilt. Generally though most guys want the checks at the cylinders so that if a hose blows between the valve & cylinder the cylinder will still be locked in position.
Click to expand...

Yep, as I slept last night I thought about that very point!!! When I first started reading about check valves, the point was that if a hose blew the cylinder would lock, basically as a safety device. The added bonus was that they also overcame leaky valves. Which I think we'll all agree now, is the primary contributor to leaky TNTs. Simply because everyone says they've not saw a cylinder leak down with a check valve installed proves that theory.

So,,,, for me, I'll buy a cylinder from someone like Redlandhill without a check valve and try it. If I suffer from leak down more than I can handle, then I'll add a check valve somewhere in the system. Maybe something like Henro did.

So,,, I guess the people on here saying they are running without check valves and don't have leak down have themselves a good set of valves!!! Hope I'm that lucky!!!
 
   / Hyd top link #36  
ovrszd said:
So,,,, for me, I'll buy a cylinder from someone like Redlandhill without a check valve and try it. If I suffer from leak down more than I can handle, then I'll add a check valve somewhere in the system. Maybe something like Henro did.
Click to expand...

Well you had better buy yourself a Prince SV stackable aux valve and add it to your system. The SV valve has several different spool configurations one of which has a DPOCV built right into the spool. Henro purchased 2 of those spools for his SV valve.
 
   / Hyd top link #37  
Most all cylinders will leak down internally. The DPOCV, when placed on the cylinder, will lock the cylinder ports unless a certain pilot or cracking pressure is maintained. The has the effect of taking the hoses and valve out of the equation.

Now, keep in mind that the rod end of the typical cylinder we use only contains about 1/4 to 1/3 of the amount of fluid volume that the base end contains. The amount of cylinder leakdown will be limited to that volume with a check valve in place since the fluid has no other place to go.

Additionally, the check valve will prevent shock loads, like bouncing down a bumpy road or tilling a rough section of ground, from activating the cylinder. According to Mark Carter this is one of the most often causes of leakdown and is a main reason why the DPOCV is placed on the cylinder.

As always, your mileage may vary.
 
   / Hyd top link #38  
I wanted to add one more thing regarding safety. This may not be as critical as with the FEL but it could happen. When a hose blows the implement weight causes the hydraulic fluid to squirt out and the implement falls to the ground pretty fast....maybe not enough time to get out of the way? When I'm working around the 3pt implements there are occasions where I inadvertantly get between the implement and tractor...no matter how safely I approach it. Imagine if a hose blew to the side links or the top link like a boxblade with rippers out pivoting forward to impale you or just falling down on your leg or foot?

Now, even though a cylinder has internal leakdown to some degree, it will never pass fluid as fast as the ruptured hose. If it did...well then it would be shot and wouldn't work at all. So with this in mind, the DOPCV mounted on the cylinder (hard plumbed) willl slow (or pervent) the falling of the tractor drag links (lift arms) or implement....giving you time to get out of there. IMO, creating a safer condition.....that's not to say it would make it a perfect world, just better than the alternative.
 
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