FEL Quick Dump

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On the regen thing, here is a good explanation from kennyd from another site. He is talking green tractors, but I think the theory applies:

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 then 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.

So, now you may be asking "this is cool and all that, but why do I need to know about it? The answer to that is simple, if you ever try to run a snow plow with two SA (single acting) cylinders, or a cylinder that drives a chute rotator on a snowblower you will soon find out that they won't work if you push the joystick to far right in the regen mode. The plow won't work because since both lines are pressurized-both cylinders will be trying to extend at the same time binding everything up. The rotator won't work because there is no weight pushing the cylinder closed like there is on the loader.
On most, if not all John Deere tractors there is a lockout the limits how far the joystick travels to the right to keep it out of the regen mode.

Thanks Dave
This explains what regen truly is. I had it all wrong thinking it was a process that actually freed up the bucket from cylinder pressure. This would cause the bucket to "flop" which I thought was what regen does. I now understand that it is the opposite and prevents the bucket from speeding up (or I should say "down") due to increased weight. The bucket actually does "speed up" almost imperceptibly but it does go a bit faster. So. I'm good on that now.

Now why Nava's tractors are still almost twice as fast may have to do with the weather in Texas today. Here it was struggling to get passed 40.* Could have something to do with it.

 

[LD1]

On the regen thing, here is a good explanation from kennyd from another site. He is talking green tractors, but I think the theory applies:

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 then 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.

So, now you may be asking "this is cool and all that, but why do I need to know about it? The answer to that is simple, if you ever try to run a snow plow with two SA (single acting) cylinders, or a cylinder that drives a chute rotator on a snowblower you will soon find out that they won't work if you push the joystick to far right in the regen mode. The plow won't work because since both lines are pressurized-both cylinders will be trying to extend at the same time binding everything up. The rotator won't work because there is no weight pushing the cylinder closed like there is on the loader.
On most, if not all John Deere tractors there is a lockout the limits how far the joystick travels to the right to keep it out of the regen mode.

Yes, excellent explanation.

That little fact in there about differing volumes of fluid due to the rod occupying space is often forgotten on this forum when discussing other things.

 

[OldGinTractors]

Thank you Dave for sharing that excellent explanation of regen. The point I was trying to make earlier in this discussion is that fast dump only occurs when the bucket is loaded. Also for all those that are timing your cycle, the printed specs will be at rated engine speeds.

 

[DavesTractor]

I'm glad that clarified, the guy that wrote it is sharp. I just copied and pasted. Honestly, I have a hard time explaining it to customers concisely in my own words in a manner that does not leave them confused. Understanding regen requires a certain basic understanding of hydraulics. I'd say if your loader works correctly, except you have a little pause when you push the stick most of the way to the right, then it picks up again after that "flat spot", then your valve is probably just fine. They ought to not refer to it as quick dump, because it is barely quicker. But putting "regen" on the sticker isn't handy either.

 

[J_J]

Statement: Regen solves this problem by actually filling both sides of the cylinder at the same time with hydraulic fluid.

Not true, as the rod side fluid is flowing out of the rod side through the valve and to the base end.

The flow in the base end is actually pushing the rod side fluid out to the valves other work port.

Regen will work whether there is a load or not.

Some Kubota tractors are different and have regen next to neutral, so they are in regen when starting to dump.

If they do not want regen, the lever is moved further to the right for power dump.

Regen is more noticeable at fast engine rpm's.

 

[DavesTractor]

Yes, excellent explanation.

That little fact in there about differing volumes of fluid due to the rod occupying space is often forgotten on this forum when discussing other things.

Absolutely! And that brings all kinds of issues with it. And that rod side of the cylinder is also less powerful when pushing from that direction. If you have 2500 psi pushing on 3 sq in of piston, you have 7500 lbs of force. Now take the rod cross sectional area out and lets say you have 2 sq in of piston surface, now you have 5000 lbs of force.

That's also why a tilt deck trailer with a looped cylinder (no power, just hydraulics looped from one end to the other) to use as a damper will flop and get air in it. Now they actually put a matching cylinder down on the frame, with the rod connected to nothing, and the oil loops through both cylinders, criss-crossed, so the amount of oil on both sides of the rod is exactly the same at all time. Novel solution. Wish I would have thought of it.

Some guy like J.J. that has forgotten more about hydraulics than I'll ever know can correct me on any of this stuff, but that is my perception. I'm not too proud to say if I write something that contradicts J.J.....go with him, he's probably correct!

 

[Shift4200]

Both the max and the 3016 take right around 4 seconds from full lock to full dump. I checked about 3 of each. You will not feel a bump or change in the lever when it regens. When yall operate the lever start pushing to the right very slow and about halfway you should see the bucket pause. then keep going and it will start dumping again. Its hardly faster than before the switch but it is just a bit. When you use the float it will take away all functions of the loader this lets the weight of the bucket and loader float while back dragging. If that's what you ment by no tilt while in float mode.

What I meant by no bucket tilt in float mode is exactly that. With the arms in a fixed position or moving up/down.. i was able to curl/dump the bucket. As soon as the arms were put into float mode, i had no control over the bucket. At first the dealer tried to tell me that this was normal, but after a little back and forth they agreed that it sounded off. The deciding factor was their test on the Mahindra front snowblower, it was able to rotate the chute while the lift/lower was in float.

After we decided that something was wrong, the dealer reached out to mahindra to see about a warranty fix. A week after that process started the linkage on the loader valve snapped. Cant help but think that my issue was related to this linkage somehow. Mahindra's solution to both was to just swap out the whole handle/valve assembly.

Didnt fix my slow ***** bucket tho.... lol

-J

 

[J_J]

To those that care to check.

You can check the end of the curl spool for regen parts.

Remove the can covering the end of the curl spool and see if you have regen parts.

A non regen spool will only have centering springs, washers, and a nut to keep things together.

You can look at the valves above to get an idea what things look like.

So, if you have the regen parts, and you push the lever to the right, and the bucket does not go faster, then I am at a loss to explain why.

You are adding more GPM's than normal, so logically the piston should move faster.

 

[J_J]

Here is a fact about regen.

You know when using a cyl, that fluid flows to tank from the rod side or the base end.

However in regen, the tank outlet is blocked by the regen spool, and all flow is routed to the base end of the cyl.

So, if no fluid flows from the tank port when using the curl spool to dump, you are in regen.

 

[mike69440]

Re: FEL Quick Dump , Long good read.

This post was a long, good read. Well I think my Kubota L39 only has regen on dump only. That explains the quick speed it will dump and the total lack of oomph it exhibits on back curl. I think Kubota was afraid the large cylinders would sheer the bucket travel stops if it had full pressure going to the piston side of the dump without regen. Still not all that much power in heavy duty back dragging.

I palyed with my new Mahindra Max28 tonight.
The regen circuit operates just as expected in the manual. back curl is strong, until to pushing to regen, and regen is faster than a no regen dump, but not impressively fast.
I think the hydraulic relief is set way too low. It will pick up the front end just barely with the loader arms, but the small bucket will get stuck driving it into a soft snow bank. The Max28 seems only marginally stronger than the very tired loader on my 30 year old Kubota B7200D.
Kubota B7200D 4x4 With loader
Why does it the Max 28 smoke more on startup (Light grey Smoke, maybe a hint of blue) than my B7200D Kubota does after it sat idle all winter? I wonder how the Max 28 was broken in the 2-1/2 hours run time it had at the dealer? (There are 4 hours on meter now) Do other people experience a good long puff of smoke on start-up?