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myyyy preciousssss!
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Discussion Starter · #1 ·
I Posted on to the end of an old thread but I think it got missed.....

I notice that when I have my bucket partially dumped and lower the loader the bucket will flatten out on the ground rather than hold its position. It will flatten to the point that its sitting flat. Certainly if i push right on the joystick again it will dump with full power and will actually lift the front wheels off the ground. I would have thought that the bucket would have held its position when set?

Thanks
 

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I have to wonder is some of these issues are related to the Indy lift kit, I am using whatever JD installs and haven't had the issues I have been reading about, in any event pressure is getting by a valve somewhere in your setup.
 

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myyyy preciousssss!
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Discussion Starter · #3 ·
Thanks Andy, so you're saying that if you angled your bucket down, then lowered the arms, that whatever angle you set on the bucket would stay that way?

Mine certainly doesnt, if its anything less than say 45 degrees it will just flatten the bucket out until its sitting on its heel.
 

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Thanks Andy, so you're saying that if you angled your bucket down, then lowered the arms, that whatever angle you set on the bucket would stay that way?

Mine certainly doesnt, if its anything less than say 45 degrees it will just flatten the bucket out until its sitting on its heel.
Yes all the tractors do and we need that ability for example to pull top soil away from an edge. Once you position it to what ever angle you can raise or lower it will bring the front wheels clear.

Now one thing even with this JD valve, it has to be all the way out for bucket control or all the way in, in our case to run the top link cylinder, the lever if you wheen is located by your right heel so we just tap it in with our work boots to switch from lader to back, sometimes we do not pull it all the way out and the bucket curl in my case is either slow or it will move the bucket slow and the top link cylinder at the same time.

I can angle that bucket at any angle we need and apply down pressure, it never changes the angle unless we go sideways on the lever, this is critical for grading top soil, as you feather out you want the bucket flatter, it is rare that we now roll as we are all onto this and have it down to a science, works perfect and a heck of a lot faster than ranking and rolling, in fact doing it this way is better than rolling as the top soil will not wash out as it is much better compacted.
 

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myyyy preciousssss!
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Discussion Starter · #5 ·
Thanks Andy, it does indeed sound like something is wrong with the hydraulic function on my tractor. I'll contact my dealer again.....he must be getting sick of me by now.

I appreciate your detailed description.

Thanks,
 

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myyyy preciousssss!
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Discussion Starter · #6 · (Edited)
I have a very strong feeling that none of my valves have this 'orifice' installed. (see pic). Is it possible someone could take a photo of how it should look installed?
Text Line Font Diagram
 

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myyyy preciousssss!
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Discussion Starter · #8 ·
Smeagol, you may want to check this thread out. Hope it helps yah out.

http://www.tractorbynet.com/forums/hydraulics/144574-jd-200cx-issue.html
oh oh oh, that does sound VERY similar to what I'm experiencing. I'm wondering if something is up with my regen circuit as I'm also experiencing symptoms with the ind lift kit.

I will try tonight holding the joystick in regen for a few seconds and see if it cures the problem.

that is a very interesting thread, much appreciated. I'll let you know how I get on.
 

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myyyy preciousssss!
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Discussion Starter · #9 ·
From the link provided by DreaminGreen above is an excellent description of regen, I have never really understood this, now I do. The post was originally wirtten by 'kubmech' in the TBN board - I hope he doenst mind me reposting his explanataion.

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The 3 position valve and the 4 position valve, both have what is known as a regenerative circuit built into the bucket dump circuit.

First let me explain what "regen" is and why.

When dumping a loaded bucket (with a good old fashioned loader control valve) the weight of the material in the bucket tends to pull the cylinders down faster than the hyd. fluid can fill the other side of the bucket cylinders. Therefore, an air pocket will develop in the cylinder causing the bucket to be a little "floppy" unless held against relief for a few seconds at the end of the dump cycle. Which creates an extra step if you want to back-drag, etc.

To solve this problem we now add a regenerative (regen) circuit into the dump function of the loader control valve.

What is "regen"? The dump function of the loader control valve applies hyd. "power" to both sides of the bucket cylinders at the same time. But Kubmech, how the heck is that going to work? Wont the cylinder just lock up and not move? No, because on one side of the cylinder the rod itself takes up space, decreasing the volume of the cylinder, on the other side of the cylinder piston there is, no rod, creating more volume. PSI=pounds per square inch, the more volume the more square inches to apply pounds, get it? O.K. so the back side of the cylinder overcomes the front side of the cyl. due to more volume and at the same time does not allow an air pocket to develop becuase of the added resistence of "hyd. power" to the front side of the cyl. allowing the cylinder to "stay tight" for subsequent operations. And as an added bonus it tends to dump faster due to the higher amount of flow/pressure to perform this operation. (Hence the "fast dump" mode the salesmen love to tell you about) In actuality the "fast dump"
mode is just derivative of the regen circuit.

Soooo..... What's the difference between 3-pos. and 4-pos. valves, besides about 35 bucks.

The 3-pos. valve has regen in the dump mode period. The problem with regen is if you want to add, say a snow plow, with power angle running off of the loader control valve, the power angle works off of single acting cylinders. With "hyd. power" being supplied to both sides of the cylinder, you will only be able to angle in one direction and that's it. (back to the whole volume-vs-psi thing again).

The 4-pos. valve has a detented position. When moving the control lever to the right, to dump (or power angle right in the case of the plow) if you choose the first detented position this is the non-regen position and will work just like the good old fashion loader control valve. If you apply a little more pressure on the control lever you will push past the detented position and move into the regen position. Thus, if you have the 4-pos. valve and want to avoid the floppy bucket syndrome you have to push full right to engage regen.

So the bottom line is; both the newer 3-pos. and 4-pos valves have the "fast dump" option. The difference is, do you want to add options to your front loader without having to add an aux valve to you're tractor or not?
 

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I don't get it. You mention air-pocket... where is the air coming from?... do you mean a vaccuum pocket?... If it's vaccuum, then all that happens is that the fluid finishes flowing in, 1/4 of a second after the cylinder movement stops. so what?... what's the problem with that?

One thing that makes my bucket and arms flop around sometimes, is when I push the actuator to the "float mode". You can float the lift arms, or the bucket tilt, or both. Sometimes when I set the bucket to float, it flops around like you mention - just get it out of float and it's back to normal.

What am I missing here?

cheers....
 

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myyyy preciousssss!
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Discussion Starter · #11 ·
Hi Wally, I'm not sure - I dont know anything about hydraulics, but what I read in that article seems to be the symptoms that I am experiencing. I will try regen'ing the bucket for a few seconds tonight and see if that makes any difference.

The problem is that I cant hold my bucket in position, it is as you say, as if it is floating.....but its definitiely out of float.

Maybe someone who knows about hydraulics can help us out?
 

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myyyy preciousssss!
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Discussion Starter · #12 ·
Well I tried a brand new 2305 out at the dealership....and it did exactly the same thing with the bucket collapsing under pressure. Now I am confused.

The mechanic tells me they have never installed an 'orofice' (see above) in the line on any of their tractors before and have never had a problem. I'm wondering if the loader arms are dropping too quickly and there is air getting in the system somewhere.

I did lift my MMM with the FEL on the weekend for cleaning underneath and I noticed from the highest position the loader will drop about 200mm in 10 minutes or so. Is this normal or symptoms of a hydraulic problem still?
 

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While it is normal to have some leakdown on the loader, 200 mm in 10 minutes sure sounds like too much to me. Are you measuring the cylinder rod or from the bucket to the ground? My guess is you have some blown seals in the cylinders. If you are measuring from the bucket to the ground, you might be leaking lift cylinders or bucket cylinders or both. Try the same test and see if both sets of cylinders are moving.
 

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myyyy preciousssss!
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Discussion Starter · #14 ·
Thanks JD110, I had lifted the MMM to clean underneath. When I lifted to full height the bottom of the mower was about 200mm off the ground. After about 10 minutes the bottom of the mower was touching the ground.
 

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When you want to back-drag or put pressure on the bucket that way, one side of the cylinder sees compression, and the other sees pressure drop. Since fluid can not compress, if the valve which controls the compression side of the movement is closed, it will hold the bucket "rigid". Only 2 things can make this happen:

1. Float position (you put the bucket in float, and didn't realize it) - both valves are open and allow free fluid flow in any direction.

2. One valve is open (the one that is under fluid compression), preventing compression from occurring, whilst the other side is still closed. In that case you will get some force (from the vaccuum you will draw on the one side), but not hydraulic-lock per-se. Your cylinder will make vaccuum with a maximum pressure of 14.7PSI - that is the equivalent pressure holding your bucket.... a lot lower than the positive pressure you can develop with a 2000 PSI pump in your tractor....
 

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Here's the problem. If you have a full bucket of material and you lower it quickly, then the weight of the loader plus the weight in the bucket will cause the loader to drop very fast.

If the loader control valve does not have a regen circuit built into it, then all of the oil in the "lift side" of the cylinder will flow back to the reservoir very quickly. However, because the tractor is most likely idling, the hydraulic pump isn't putting out very much oil. That oil is needed to fill up the "down side" of the lift cylinders at the same rate that the oil is leaving the bottom of the cylinder but the pump can't do this on its own. Since the "down side" of the cylinders is unable to get the needed oil, a vacuum is created inside the cylinder and this vacuum sucks air past the seal the cylinder rod passes through. That's where the air comes from.

This air will be forced out of the cylinder when you either apply downpressure to the cylinders or you raise the loader to full extension. Some air will leave via the rod seals and the rest will leave via the hydraulic hoses and be dissapated when it reaches the reservoir. The little "in-line orifice valve" is installed on the line leaving the loader control valve and going to the bottom of the lift cylinders. This is a "restrictor valve". It most likely has a spring loaded orifice inside that gets out of the way when the loader is being raised but comes into play when the loader is lowered.

When the loader is told to lower, the oil leaving the cylinders now has to pass through a much smaller orifice, thus dramatically lowering the rate of descent and hopefully preventing air from being sucked past the cylinder seals. This will allow the loader to lift the bucket at the same speed it did before installing this valve but prevent the loader arms from dropping at an accelerated speed when the bucket is full.

Why the loader valve on this tractor does not have a regen circuit is beyond comprehension. A regen circuit allows oil that is flowing out of the bottom of the cylinders to immediately flow to the top of the cylinders instead of going back to the reservoir. There's a special regen circuit inside the loader control valve to look after this problem. It's all about keeping both sides of the cylinders filled with oil at all times so you do not experience the floppy bucket and loader issues you are complaining about. There's nothing new about regen circuits in loader control valves. They've been around a long time.
 

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Caseguy -that is the best explanation of Regen I have ever seen. thanks.

vacuum sucks air past the seal
That's surprising, as the seals are designed for much more pressure than the 14.7PSI that vaccuum is. Of course the argument is that the valve has a one-way pressure-induced sealing action, that does not work in reverse - however if that was the case, then air ingestion would be a rampant problem everywhere - a problem that is easily fixed with a 2-way seal. Assuming that JD uses the "better" cylinders with a 2 way seal - air ingestion is not the problem, but basic vaccuum generation still is....

oil that is flowing out of the bottom of the cylinders to immediately flow to the top of the cylinders
Makes perfect sense, and the speed of "dumping" is still regulated by the valve and operator input.... the outflow from the lifting side is "slowed" by the valve... the orifice just limits the "maximum speed" at which this can happen....

THe 2305 has a regen valve... it's not an option. By putting the control into the regen position, all you've accomplished is put the bucket in float mode... however, that position can not be modulated in speed, hence the general idea of the orifice - to slow down the "fast dump" mode. The same "extra" position in the DSCV lift arms is actually called 'float' instead of regen - but it behaves the same way..... especially since this is an open center hydraulic system, meaning, you are not recycling "zero pressure" fluid to and from the tank, but rather to and from each end of the piston / cyclinder in a regen fashion.

Now keep in mind that once the SCV is set to regen (or float) position, it does not pop back by itself when you let go of the stick... it stays there until you "click" it back. So if you were tilting the bucket down to position it, you could have actually put the stick in regen mode, and left the valve open... once you lower the arms and the bucket down, the bucket tilts freely.....

Anyway - I have seen this behaviour only if I accidentally left the bucket in float (regen) mode. I have back-dragged without a problem, many times, as long as I set the valve properly.

cheers....
 

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Caseguy -that is the best explanation of Regen I have ever seen. thanks.

vacuum sucks air past the seal
That's surprising, as the seals are designed for much more pressure than the 14.7PSI that vaccuum is. Of course the argument is that the valve has a one-way pressure-induced sealing action, that does not work in reverse - however if that was the case, then air ingestion would be a rampant problem everywhere - a problem that is easily fixed with a 2-way seal. Assuming that JD uses the "better" cylinders with a 2 way seal - air ingestion is not the problem, but basic vaccuum generation still is....

Keep in mind that these are OIL seals, not air seals. It doesn't matter if air gets sucked into the cylinder however, if the air brings dirt in with it, then that's a problem. If the regen circuit is properly designed, then oil will flow into the top end of the cylinder just as fast as it is needed. There is a higher volume of oil in the bottom of the cylinder due to the fact that the cylinder rod isn't there. As such, the oil being pushed out of the bottom of the cylinder is more than enough to keep the entire upper part of the cylinder 100% full, especially since the pump flow, as meager as it might be, is also being directed into the top of the cylinders. The rod seals are there to keep that oil from escaping. As long as they do that job, then the air situation is mostly just an inconvenience, contaminant issue aside.

oil that is flowing out of the bottom of the cylinders to immediately flow to the top of the cylinders
Makes perfect sense, and the speed of "dumping" is still regulated by the valve and operator input.... the outflow from the lifting side is "slowed" by the valve... the orifice just limits the "maximum speed" at which this can happen....

THe 2305 has a regen valve... it's not an option. By putting the control into the regen position, all you've accomplished is put the bucket in float mode... however, that position can not be modulated in speed, hence the general idea of the orifice - to slow down the "fast dump" mode. The same "extra" position in the DSCV lift arms is actually called 'float' instead of regen - but it behaves the same way..... especially since this is an open center hydraulic system, meaning, you are not recycling "zero pressure" fluid to and from the tank, but rather to and from each end of the piston / cyclinder in a regen fashion.

Now keep in mind that once the SCV is set to regen (or float) position, it does not pop back by itself when you let go of the stick... it stays there until you "click" it back. So if you were tilting the bucket down to position it, you could have actually put the stick in regen mode, and left the valve open... once you lower the arms and the bucket down, the bucket tilts freely.....

Anyway - I have seen this behaviour only if I accidentally left the bucket in float (regen) mode. I have back-dragged without a problem, many times, as long as I set the valve properly.

cheers....
Float position is separate from the regen circuit. Float only occurs on the loader lift arms, not on the bucket cylinders. Float allows the loader lift arms to move up or down regardless of the position of the tractor's wheels. If the loader is in float while backdragging and the front wheels of the tractor either climb a grade or drop into a depression, the bucket is neither lifted nor does it feel any downpressure beyond its own weight plus any additional weight from the loader arms.

Float has a detent on the end of the actual spool to hold it in Float until such time as the operator chooses to end the Float operation. The oil that moves from the top of the cylinder to the bottom of the cylinder and back again, does not pass through the regen circuit. Instead, it moves internally in the grooves machined into the actual spool.
 

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myyyy preciousssss!
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Discussion Starter · #19 ·
wow, caseguy and wally this information is gold, and exactly the sort of stuff I'm looking for. I'll have to read it a few times for it to all sink in.

The manager of the dealership came out last night and said that the problem was air in the system which will work its way out over time. He said they have never istalled an orifice in the hundreds of 2305's they have sold without a problem - I'm wondering if this IS the problem. His advice was to give it a good workout and see how it goes.

Your information is much appreciated.
 

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The manager of the dealership came out last night and said that the problem was air in the system which will work its way out over time. He said they have never istalled an orifice in the hundreds of 2305's they have sold without a problem - I'm wondering if this IS the problem. His advice was to give it a good workout and see how it goes.

I'm not going to beat up the dealership manager because he obviously has no background in hydraulics.

You need to understand a couple of things. Essentially, oil does not compress to any degree when it is a pure fluid. If air gets mixed with oil, then foamy oil is created and that can be compressed. However, it's the air that is in the oil that is being compressed, not the actual oil. When the foamy oil is returned to the hydraulic reservoir, the air gets released from the oil and then dissipates through the vent in the fill cap on the reservior. The oil contains anti-foaming agents to limit foaming and to help dissipate it once it is no longer under pressure.

If this did not happen, then foamy oil would end up being sucked back into the hydraulic pump. This would cause the pump to cavitate. Pump wear would increase dramatically because the foamy oil would not be able to maintain that necessary film of oil between the pump gears that keeps them from actually touching each other as metal on metal. Foamy oil is spongy oil and your hydraulic cylinders would not raise smoothly and evenly.

He's right when he says that air will work its way out of the system but that air has to leave the instant the oil is delivered back to the reservoir, not minutes, hours, days or weeks later like he seems to be implying.

If this is a new machine that is still under warranty and the dealership seems incapable or unwilling to doggedly find the real problem, then I suggest that you contact Deere directly and ask for technical assistance. This air ingestion issue should not be taken lightly. Everytime you use this tractor you could be causing accelerated wear on certain components that won't show up until the tractor is no longer under warranty and then guess who pays?

If the dealership has sold 100's of 2305's with no problems like you describe, then the manager's suggestion is stupid. You don't keep working the crap out of piece of machinery that is exhibiting an unusual problem. What a real manager would do, is send a truck and float to your home with a loaner unit and pick up the problem tractor. He would then instruct his best hydraulic mechanics to find what's really going on with this tractor with a view that it does not leave the shop until it's repaired and fully tested.

This is your money he's playing with and as I see it, you're just being jerked around. Time to jerk back while the warranty is FRESH.

Get Deere involved.
 
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