Dirt Moving Rear hydraulic remote .

[ovrszd]

Sure it will...the air can't go anywhere the same as the oil...enough force will compress any air which will push back when said force is lessened...If the cylinder has been fully cycled I doubt there is any air anyway...

No it won't. And you fully explained why.

 

[ovrszd]

Sounds just the same as mine except mine goes in and out as it goes over the bumps.

There is still the possibility of cylinder failure. This will be harder to test.

You have already tried cycling and the uncoupling. Was this done with no load on the cylinder? If so then we would assume you've purged the cylinder. If so then it should not move with hoses uncoupled if no air exists. If it moves then that would indicate internal cylinder problems.

With a new cylinder this is very rare. But possible.

 

[Rustyiron]

Is there a correct way of doing this. In the instructions I received with the cylinder it says not normally required to do anything other than cycling it a few times, do you know of another method. Thanks

First try to determine if this is an air problem. You say it moves. Trapped air will give you a spring effect as the air can be compressed and you can have this springy action. I'd hang an implement on the 3 point, raise it up and physically pick up on it observing what's going on at your top link, maybe a wrap of electric tape on the cyl. rod to observe movement better. Bleeding the air is not too different than your brakes, but remember you have both sides of the cylinders along with the hoses.
Normally this air will work it's way out by cycling a few times, but I've had cylinders that have a built in check valve that takes hundreds of psi to open making bleeding interesting, then there's the possibility of similar "quirks" with the tractor valve and plumbing.

 

[ovrszd]

Or cycle the cylinder to purge. Stop cylinder in mid stroke. Set the implement down with 3pt. Uncouple hoses. Drop 3pt lever to bottom. Leave it overnight. If cylinder is bypassing internally it will compress considerably. Depending on weight of implement it may not fully compress but will show considerable movement.

Eric, trying to brainstorm ways to test cylinder integrity.

 

[bryn67]

First try to determine if this is an air problem. You say it moves. Trapped air will give you a spring effect as the air can be compressed and you can have this springy action. I'd hang an implement on the 3 point, raise it up and physically pick up on it observing what's going on at your top link, maybe a wrap of electric tape on the cyl. rod to observe movement better. Bleeding the air is not too different than your brakes, but remember you have both sides of the cylinders along with the hoses.
Normally this air will work it's way out by cycling a few times, but I've had cylinders that have a built in check valve that takes hundreds of psi to open making bleeding interesting, then there's the possibility of similar "quirks" with the tractor valve and plumbing.

Thanks. I have tried something similar earlier in my post. My tests using a stick rake showed that the ram compressed when hoses were disconnected and 3 point hitch lowered to ground but the rake tines were grabbing on the concrete and I was having to lift the rake by hand in order to allow the ram to move. Not very good on my back. I will try the same test again today but this time will use a dolly under the rake but I will have the same question as before!! Is the movement air or fluid?? Also with bleeding, what’s the process for letting the air out if it’s air. Finally if I do manage to get the air out will I need to do this procedure again if I remove the top link for a while. Makes me wonder if I should stick to the tried and tested screw. Thanks all.

 

[bryn67]

Thanks. I have tried something similar earlier in my post. My tests using a stick rake showed that the ram compressed when hoses were disconnected and 3 point hitch lowered to ground but the rake tines were grabbing on the concrete and I was having to lift the rake by hand in order to allow the ram to move. Not very good on my back. I will try the same test again today but this time will use a dolly under the rake but I will have the same question as before!! Is the movement air or fluid?? Also with bleeding, what’s the process for letting the air out if it’s air. Finally if I do manage to get the air out will I need to do this procedure again if I remove the top link for a while. Makes me wonder if I should stick to the tried and tested screw. Thanks all.

Note. I forgot to mention that when the stick rake is up in the air the top link moves in and out “ solid” there does not appear to be any sponginess and so doesn’t feel as though there’s any air in the cylinder.

 

[ovrszd]

If the cylinder moves with the hoses uncoupled slowly overnight type movement that's leakage within the cylinder. If the cylinder moves relatively freely back and forth with minimal force but displays elasticity that is air.

 

[K5lwq]

Pleasantly surprised this thread has not gone south.

If the cylinder is fully extended and no air in the system, I don't see how it could retract with hoses plugged even if the cylinder is bypassing internally. I would suggest cycling the cylinder with no weight to eliminate the possibility that it extends faster than the hydraulic pump can fill the cylinder.

My top link has always held pretty well.

 

[countrybumpkin]

I’m shocked it took this long before that was brought up.

 

[bryn67]

Pleasantly surprised this thread has not gone south.

If the cylinder is fully extended and no air in the system, I don't see how it could retract with hoses plugged even if the cylinder is bypassing internally. I would suggest cycling the cylinder with no weight to eliminate the possibility that it extends faster than the hydraulic pump can fill the cylinder.

My top link has always held pretty well.

I cycled it again today nice and slow. I took it for a test run with a stick rake and the ram went in and out like a fiddlers elbow. I took it back and put the old screw type back on. I am running out of ways to try and bleed it.

 

[Amvcane]

I’m shocked it took this long before that was brought up.

X2 The laws of physics cannot be broken.

 

[ovrszd]

I've been involved in some very lengthy and technical discussions about this problem. It's hard to discuss without some getting aggravated and insulting. Took me a long time to accept some of the theories.

Here's one. If you unplug the cylinder mid stroke, and put an extending load on it, it's possible for the cylinder to extend without internal cylinder failure.

Here's one. If you unplug the cylinder mid stroke, and put a compression load on it, it's not possible for the cylinder to collapse, even if the internal gland has no O-rings or seals on it.

These theories require thought and discussion to accept.

 

[ovrszd]

Here's what my pea sized brain has stored from this discussion so far.

In normal operation the top link "appears" to have air in it. Moves in and out based on load. Not sure if it is able to fully extend or collapse.

When the top link is uncoupled mid stroke and put in use it still moves in and out based on load. Not sure if it is able to fully extend or collapse.

OP's last comment indicates that the top link displays no control when in use. Completely moves in reaction to load as if it's not coupled to the tractor.

Maybe I've missed something?

 

[ovrszd]

Pleasantly surprised this thread has not gone south.

If the cylinder is fully extended and no air in the system, I don't see how it could retract with hoses plugged even if the cylinder is bypassing internally. I would suggest cycling the cylinder with no weight to eliminate the possibility that it extends faster than the hydraulic pump can fill the cylinder.

My top link has always held pretty well.

When I was trying to find a solution to my problem Brian from Fit-Rite sent me a restrictor. I put in in the cylinder circuit. Purpose being to keep the system from sucking air because of fast extension. It did not help my situation one bit. I finally took it out because I hated how it slowed the use of the cylinder. It would actually make my hydraulics scream against the relief valve because it slowed the flow so much.

 

[npalen]

I am also a member of the "funny top link cylinder club". I guess I'm of the opinion that, if I need to "stiffen" the cylinder, I will raise the 3PT fully then SLOWLY extend the top link cylinder making sure to not introduce any air. May need to do this several times and the results seem to be only a temporary fix. I also have added restrictor fittings.

As ovrszd mentions above, there is a difference with issues depending whether extending and retracting. The issues encountered with top link cylinders and FEL bucket cylinders may have some similarity due to the fact they are normally extended under load.

Industrial hydraulic presses, shears and brakes use what is called a counterbalance valve for several reasons including safety as well as not pulling a vacuum when lowering the ram. They all, or most, extend the cylinders on the downstroke same as a top link cylinder. There is a lot to be said for pilot operated checks on a top link setup especially on the rod end port.

Maybe someone needs to design a top link cylinder that extends rather than retracts under load??????

 

[ovrszd]

Good stuff npalen.

I've often wondered if DPCVs prevent the air problem??? I've not been able to wrap my mind around it enough to come to conclusion.

With DPCV it requires pressure to open the valve and allow the cylinder to move. In theory that would prevent any type of vacuum because the valve would close as soon as the pressure dropped below the prescribed psi setting within the valve.

So maybe they would solve the problem??

 

[ptsg]

Good stuff npalen.

I've often wondered if DPCVs prevent the air problem??? I've not been able to wrap my mind around it enough to come to conclusion.

With DPCV it requires pressure to open the valve and allow the cylinder to move. In theory that would prevent any type of vacuum because the valve would close as soon as the pressure dropped below the prescribed psi setting within the valve.

So maybe they would solve the problem??

Yes it solves that issue. Also it's safer in case of a hose blow up. That's why it's a requirement on top links on some countries.

 

[ovrszd]

Yes it solves that issue. Also it's safer in case of a hose blow up. That's why it's a requirement on top links on some countries.

Good stuff!!! Thanks for that clarity.

I'm now using my Ford with Hydraulic Top Link more now for blading/grading purposes. I may add a DPCV since I know now it solves the problem. I hated to convert it and then still have the same problem. Thanks.

 

[ptsg]

Good stuff!!! Thanks for that clarity.

I'm now using my Ford with Hydraulic Top Link more now for blading/grading purposes. I may add a DPCV since I know now it solves the problem. I hated to convert it and then still have the same problem. Thanks.

The DPCV kits are fairly inexpensive and some hydraulic shops with cut the hard lines for you, once you get them the distance between ports.

 

[ovrszd]

The DPCV kits are fairly inexpensive and some hydraulic shops with cut the hard lines for you, once you get them the distance between ports.

Yep. I think I'll do that. If/when I do I'll post the results on this thread.