GC1700 series fast dump loader function??

[atsah]

Sorry, but the physics of the circumstance does not support your observation.[/I]

I went out this morning and tried different things with the loader to make sure I wasn't mistaken after I read you're post, it does what I posted earlier and both tractors labored in doing so. My JD does the same, the chances of me having two "special" loader valves on two different brand tractors is pretty slim, my luck isn't very good..

 

[MaineGuy1]

I went out this morning and tried different things with the loader to make sure I wasn't mistaken after I read you're post, it does what I posted earlier and both tractors labored in doing so. My JD does the same, the chances of me having two "special" loader valves on two different brand tractors is pretty slim, my luck isn't very good..

Yes, but I think you are proving his point. If it is lifting your tractor off the ground you are not in any type of fast dump.
Edit: Ok, sorry, I re read the other posts. I always thought fast dump just released the hydraulic fluid but maybe that is not the case. I guess I need to ask my dealer, and maybe they won't even know, lol.

 

[atsah]

you are not in any type of fast dump.

Yes I am.. It doesn't matter to me what someone else thinks about it, it works the way it works when I use what I have, some of these conversations assume someone isn't telling the truth for some foolish reason.

I went out this morning and proved it to work the way I thought it did, I don't know what to tell ya other than there is nothing more for me to add to this conversation. So carry on fellas..

 

[MaineGuy1]

Yes I am.. It doesn't matter to me what someone else thinks about it, it works the way it works when I use what I have, some of these conversations assume someone isn't telling the truth for some foolish reason.

I went out this morning and proved it to work the way I thought it did, I don't know what to tell ya other than there is nothing more for me to add to this conversation. So carry on fellas..

Read my complete post and I admitted I could be wrong. Maybe you didn't read it all.

 

[atsah]

Read my complete post and I admitted I could be wrong. Maybe you didn't read it all.

I read it, I'm just getting aggravated with people that think everyone is a moron, I have been messing with tractors since the 60's and know my fair share about them. I didn't mean to get on you about it, sorry..

AND you edited your post after I read it. So keep that in mind in the future, once you post people read it and don't go back and read it again..

 

[JWR]

I respectfully disagree, if you float the bucket using fast dump, and it's flat on ground, if you attempt to push against a snow or dirt mound, it WILL lift the front wheels as the bucket rotates the front lip downward, found out this learning years ago what position does what on the loader stick!

What you describe is the forward motion of the tractor causing the bucket (whose tip is caught in the ground or something solid) to rotate downward as the loader frame rides up over it. Sure, that can and does happened which does not contradict my point at all. Really that has no relationship to a fast dump feature. Atsah did not describe any forward motion into something hard/immovable, he was just talking snow.

I'm saying that 1) a quick dump feature on a front end loader puts the bucket into free-fall or the same thing as float dumping rotation with only gravity driving the bucket downward. And 2) that if Atsah's FEL bucket lifted the front end off the ground under hydraulic force (not forward motion riding up over an obstacle) then it was not in fast dump mode at that point.

 

[aczlan]

I'm saying that 1) a quick dump feature on a front end loader puts the bucket into free-fall or the same thing as float dumping rotation with only gravity driving the bucket downward. And 2) that if Atsah's FEL bucket lifted the front end off the ground under hydraulic force (not forward motion riding up over an obstacle) then it was not in fast dump mode at that point.

Respectfully, you are incorrect. As I said before, the quick dump or regen dump feature ties both hydraulic lines to the bucket dump cylinders together with the high pressure input line from the hydraulic pump (or the next valve closer to the hydraulic pump).
It works because of the difference in surface area between the base end of the cylinder and the rod end of the cylinder.

Because the rod end has a greater surface area, the force pushing the bucket to dump is greater than the force pushing the bucket to curl.

Aaron Z

 

[JWR]

aczlan: That's OK. We disagree. You could be right. I don't think so, but honorable people disagree honorably ! I'll do some homework.

I also want to mention that I regret Atsah came away a few posts back with an impression "people that think everyone is a moron." I never intended anything remotely similar to that and I'm betting neither did MaineGuy1. These machine mechanisms are often complex and I think we have all seen subtle differences between brands, models, situations, etc. On top of all that, it is difficult to be 100% accurate (getting across exactly what we mean, be it right or wrong) based on just using English. To me there's nothing wrong with honest disagreement and I suspect we learn more from those than we do from bland concurrence.

These forums are valuable because people are able to freely describe a problem, ask a question, express opinion, give benefit of experience, and explain how they believe something works. It would be fairly miraculous if we didn't disagree at times. In my 8 years on here and more than 1300 posts I can only recall once that I felt another guy was so far out of line that he earned a place on my permanent sh list. None of that applies to any of you on this thread.

 

[aczlan]

aczlan: That's OK. We disagree. You could be right. I don't think so, but honorable people disagree honorably ! I'll do some homework.
.

Do you have regen dump on your tractor? If so, can you try something to prove if you are correct or not?
1. Put the loader lift circuit into float with the bucket curled, the engine running and the tractor not moving
2. Move the loader to put the bucket cylinder into regen dump position
If you are correct, it the bucket will move until the bottom is flat, then stop.
If I am correct, the bucket will keep moving until it goes to full dump (you might need to give it a little throttle to make it do that).
I say this because I have a tractor with a regen dump circuit on it that I had to disable to make the snowblower chute angle work, so I looked into what makes it work (I initially thought the motor was bad)
Here is the flow diagram for the bucket circuit of the Surplus Center regen valve that I linked to before:

Each box is a different position for the bucket circuit in the valve, the top two connections are the lines to the bucket (A and B) The bottom two are the pressure inlet (P, on the left and T, on the right).
Note that in the far left box (regen dump), the P, A and B lines are connected.

Here is the flow diagram for the loader arm circuit of the Surplus Center regen valve that I linked to before:

Each box is a different position for the bucket circuit in the valve, the top two connections are the lines to the loader lift cylinders (A and B) The bottom two are the pressure inlet (P, on the left and T, on the right).
Note that in the far left box (float), the P, T, A and B lines are connected, this is different from the regen circuit and is why the loader will lower in float vs raising.
In theory, if you swapped the lines for the loader lift and bucket dump circuits, it would lift with regen dump position if the pressure difference was enough.
As for the pressure differential, with a 2" bore, 1" rod cylinder and 2000PSI fluid, in regen mode, you would have 4712# trying to retract the cylinder and 6283# trying to extend the cylinder per the Surplus Center calculator at: Surplus Center

So, each cylinder would be trying to dump with 1571# of force.

Aaron Z

 

[JWR]

Yes, I do have regen dump on my tractor. I don't understand your test. If the loader lift (e.g. frame control) is in float it just lowers to the ground until the bucket stops it and sits there. One does not move the loader to put the bucket into regen dump position but rather you move the joystick to the far right (position 6 in the diagram below) beyond the normal "force downward" position. The bucket stops of course when it lies flat on the ground. It got there by gravity. It won't lift the tractor front up at all since the loader valve (in regen dump) is allowing rapid flow back to the reservoir and not affecting the movement of the curl/dump cylinders. The bucket will not force the tip downward in regen position. It could not lift the front end anyway in the test you suggested because the loader frame was to be in float mode so the loader frame would just rise, not the tractor, if additional dumping motion happened in the regen mode.

I SAY all that as if I'm on the thing, but my tractor is 300 miles away and I can't just go get on it. I travel to the farm once a month. I just know that is how it acts from having used it for the past 8 years. [I'll certainly do due diligence and run your test next time I am back there.] I hesitate to have all these folks bored with details of my situation but ...I'll try to be concise and tell it:

The original loader valve (NIMCO CV152) brand new, 2011, was defective such that one could not force the bucket tip downward regardless of control position. At least 2 other loader valves on MF 2650/60 series tractors new on the lot at a dealer had the same issue (he had sold a 3rd and it reportedly had the same issue.) On top of that, the AGCO depot level parts people sent the dealer a new CV152 which was put on my tractor replacing the original. It was bad with the exact same disease. AGCO gave the dealer little/no help, the dealer was baffled, and with me only there once a month it was ... a mess. Finally I contacted NIMCO myself, their engr told me "they had let a few bad ones out the door" and he sent me a kit to replace the spool control assembly out on the end of the loader valve. I fixed the thing myself that way. Had to do with cumulative tolerances out along the length of the spools. After that I can lift the front end off the ground using dump position but not regen dump of course.

Here is the applicable page from the operator's manual:




Notice that in position 5 the bucket dumps and...hydraulic pressure forces the cutting edge down. In position 6 (the regenerative position) the weight of the bucket and contents dumps potentially faster than it would under normal hydraulic pressure and (since the hyd fluid is bypassing everything and going straight back to the reservoir, cavitation is prevented.) If you had a very heavy bucket load and went into dump as hard as you could go WITH hydraulic pressure, the load would in effect be sucking fluid too fast through the cylinder leaving air space behind (hydraulic flow not keeping up with the drop rate) and making for potential cavitation damage over time. So if you want to do a lot of heavy loader work dumping as quickly as you can -- go to the regen position and let gravity do the faster dumping. That's the way I read the manual and that is my understanding.

I hasten to say this situation with an 81 horse 2660 and a DL250 loader is probably different from the behavior of a DL95 or whatever the OP is using on his GC1700. Intuitively I would think that the GC1700 series is much less likely to have this more complicated type loader valve.

You lose me in the higher and lower pressure discussion. So far as I know there is only one high pressure level from the pump, controlled at that level by a relief valve, and fed to where ever the control valve directs it.

 

[aczlan]

You lose me in the higher and lower pressure discussion. So far as I know there is only one high pressure level from the pump, controlled at that level by a relief valve, and fed to where ever the control valve directs it.

Let's start here, since the difference is what makes regen dump work.
Here is a generic hydraulic cylinder:

If the bore (the diameter of the inside of the cylinder housing) is 2" and the diameter of the rod is 1", there is enough surface area that if you put fluid into the blind or base end at 2000PSI (with no pressure on the rod end) it will try to extend with 6283# of force.
If you put the same 2000PSI into the rod end, the surface area of the disc on the end of the rod is smaller due to the diameter of the rod, so it will only retract with 4712# of force.
If you put 2000PSI into both sides with them tied together (like regen dump does), it will extend with 1571# of force due to the difference in surface area on the disc that is mounted on the end of the rod for the hydraulic fluid to push on.

Does that make sense? Do you follow me so far?

Aaron Z

 

[Snobdds]

All I know is, when I put the joystick all the way to the right, the bucket will dumb noticeably faster...

Which is all I want...

 

[aczlan]

KennyD explained it well:

Regen is a "feature" of most modern FEL (Front End Loader) valves, it's on the Dump (joystick far right) circuit, and is also referred to as "Fast Dump". The reason it is nice to have is that without it, the weight of a filled bucket can actually "pull" the bucket down faster than the fluid can enter the other side of the cylinder, this will create a air pocket and give the bucket a "floppy" feeling until the joystick is held in the dump mode a few seconds to refill the cylinder pushing the air past the seals. So we add "regen" or "regenerative" function to the valve.

Regen solves this problem by actually filling both sides of the cylinder at the same time with hydraulic fluid. But how will that work you might ask? Well, because there is more volume on the side of the cylinder that extends it since the rod is taking up space in the other side, it "overpowers" the rod side and lets the cylinder extend-thereby dumping the bucket. So since now both sides of the cylinder are "pressurized", the air pocket can not develop, eliminating the "floppy" bucket syndrome. One other added bonus is that the bucket actually dumps faster due to the higher flow rate required to do all this, that's why it's referred to as "fast dump" sometimes.

Aaron Z

 

[JWR]

Aaron: Outstanding posts #31 and #33. I really appreciate your patience here !! Causes me to re-think several issues, cases where I thought something was wrong, etc. I find it interesting that my loader manual and your explanations do not contradict one another -- it's just that the operators manual [post #30]
did not go far enough to explain the situation. I am stunned. Never too old to learn. In post #31 you asked "Does that make sense? Do you follow me so far?" and the answer is YES, for sure.

Obviously I was wrong in several posts above, based on thinking that fast dump was strictly gravity replacing hydraulics.

I am assuming that "regenerative fast dump" is standardized terminology such that your explanation applies to all brands and sizes of loaders if they have the feature. Given the added complexity and cost of the loader valve, I am still surprised that the feature is found on smaller tractors like the GC1700 series.

 

[aczlan]

Aaron: Outstanding posts #31 and #33. I really appreciate your patience here !! Causes me to re-think several issues, cases where I thought something was wrong, etc. I find it interesting that my loader manual and your explanations do not contradict one another -- it's just that the operators manual [post #30]
did not go far enough to explain the situation. I am stunned. Never too old to learn. In post #31 you asked "Does that make sense? Do you follow me so far?" and the answer is YES, for sure.

Obviously I was wrong in several posts above, based on thinking that fast dump was strictly gravity replacing hydraulics.

I am assuming that "regenerative fast dump" is standardized terminology such that your explanation applies to all brands and sizes of loaders if they have the feature. Given the added complexity and cost of the loader valve, I am still surprised that the feature is found on smaller tractors like the GC1700 series.

Thank you, glad I was able to make sense.
As for added complexity, as I understand it, all that they need to do is add another half inch or inch to the loader spool and grind a different set of openings into it. Then they put a different spring on the outside and its good to go.

Aaron Z

 

[JWR]

...
As for added complexity, as I understand it, all that they need to do is add another half inch or inch to the loader spool and grind a different set of openings into it. Then they put a different spring on the outside and its good to go.

Aaron Z

That's the way it seemed to me when I had my loader valve apart, I just did not understand what I was looking at. There is another (lengthy textbook style) treatment 'of regen fast dump' at BOOK 2, CHAPTER 17: Regeneration circuits | Hydraulics & Pneumatics. The Hoyetractor article is by far the most readily available insight on the web into the feature.

The longer the spool gets, the greater the chances of the "plus and minus" tolerances adding up in one direction along the length of the spool. That is what NIMCO said had happened with their valves. In other words, each dimension was within tolerances originally set, but if all or most were off to either plus or to minus side, then the one out at the end was in trouble. The kit they sent me was to fix that out at the far end.

 

[atsah]

Sorry, but the physics of the circumstance does not support your observation. The fact that it "picks up the front of the tractor doing so" proves that the bucket dumping motion is hydraulic driven. There is nothing about a quick dump feature that provides more hydraulic pressure nor more sudden volume of hydraulic fluid flow nor anything else (other than gravity) to produce the motion. Just does not happen. In fact, the bucket being driven downward under hydraulic pressure proves you were NOT in the quick dump mode at that point (!) You were in the normal dump position of the loader valve.

This was you're reply to my post. To me this post says, atsah, you have no idea what your talking about because what you explain is not possible.

That's why I kind of got upset, make sense?

 

[JWR]

This was you're reply to my post. To me this post says, atsah, you have no idea what your talking about because what you explain is not possible.

That's why I kind of got upset, make sense?

Well, I am sorry. It was not meant that way at all. I was trying to be strictly factual, not nasty. At that point, it looked to me like your observations and what I believed to be facts were directly contradictory. Maybe there is a better choice of words to say "I think you are wrong." Turns out I was wrong anyhow (aside from my tact or lack of it.)

 

[atsah]

Well, I am sorry. It was not meant that way at all. I was trying to be strictly factual, not nasty. At that point, it looked to me like your observations and what I believed to be facts were directly contradictory. Maybe there is a better choice of words to say "I think you are wrong." Turns out I was wrong anyhow (aside from my tact or lack of it.)

It’s no problem at all.. Technically I really didn’t know myself why the loader worked the way it does, I learned something myself.

 

[lpakiz]

OK, I hesitate to jump into the middle of this, but i believe that “fast dump” and regenerative circuit” are one and the same.
As I understand it, these valves are very valuable on a woodsplitter, where the “retract” doesnt need to develop much pressure, but VOLUME is most important. The more VOLUME of oil entering a cylinder port, the faster that cylinder travels.
So, as I understand it, in RETRACT) the “regen” valve combines the normal oil flow from the pump to the retract port but simultaneously intercepts the “return” oil from the “push” side of the wood splitter (which would normally be returned to the resevoir) and directs it into the retract port. So now “retract” has its normal volume of oil, PLUS the intercepted (diverted) oil from the push side (which would normally be returned to the resevoir) and uses the combined flow to move the piston really fast, but pretty weak. Perfect for a wood splitter or loader bucket curl function, where you want speed but dont need the power (force).
Not very useful on most hydraulic circuits, but works great on these functions.
And I tend to agree that these valves could be more trouble than they’re worth, especially if they are not designed correctly. Then again, engeneered correctly, there might be some extra value in them.
I disagree that the dump cylinder can “suck air from the resevoir”, because said air would also need to be sucked thru the pump and valve in order to get into the cylinder.