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Discussion Starter · #1 ·
What is "Regen" or the "Regenerative" function of a FEL Valve? Read it here ;)

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.
 

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THANKS Kenny, that was very well explained. I really never know how it worked or what it was for, only sort of. Excellent information.:good2: Keep it coming.
 

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Had heard talk about "regen", knew it was there but not how it worked. Do now in an easy to understand way. Plan to add some hydraulic circuits on the 3520 in the future so I am trying to get a good, basic overview on the entire big picture first. Thanks! and keep it coming.
 

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Discussion Starter · #4 ·
THANKS Kenny, that was very well explained. I really never know how it worked or what it was for, only sort of. Excellent information.:good2: Keep it coming.
Had heard talk about "regen", knew it was there but not how it worked. Do now in an easy to understand way. Plan to add some hydraulic circuits on the 3520 in the future so I am trying to get a good, basic overview on the entire big picture first. Thanks! and keep it coming.
Thanks guys...I am taking request's for more articles.
 
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How about a version of my "How to think through adding circuits" that I put on TBN?? Could just cut and paste and edit??.....

How to add worklights??

How about a glossary of terms and definitions??

-Jer.
 

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Kenny,
On my 445 I have the scv's for a loader. I use them for my snow blower and one of the levers is also used for the deck lifting. When I put the snow blower on, the up and down for the snow blower works very fast. The chute rotation is slow for a bit, then its fast. It been a while since I had the snow blower on, but I remember turning off the deck hydraulics, but that only helps a little. Does that slowness have to do with the regen cycle? How can I stop it on that model? Thank you!
 

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Discussion Starter · #7 ·
Kenny,
On my 445 I have the scv's for a loader. I use them for my snow blower and one of the levers is also used for the deck lifting. When I put the snow blower on, the up and down for the snow blower works very fast. The chute rotation is slow for a bit, then its fast. It been a while since I had the snow blower on, but I remember turning off the deck hydraulics, but that only helps a little. Does that slowness have to do with the regen cycle? How can I stop it on that model? Thank you!
I don't think that valve has regen...the operation of the chute from slow to faster is probably the cable that wraps the chute binding up.
 
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It does it both ways and consistent as all get out. I also check and lube the cables. My guess was that the hydo deck lift was not shutting off completely and it was powering that. When that was extended or contracted compeltely the chute moved at full speed? Maybe I have a bad valve to shut off the deck?
 

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I do appreciate that the Regen Function description above is being given in Lay terms, however; I would like to point out a few general errors in the description itself.

- There is no 'Air Pocket'. Without the necessary volume of fluid to fill the cylinder base end, the huge pressure drop causes a void to form, which is due to the pressure in the cylinder being below the hydraulic fluid's Vapour pressure. The fluid is stretched to fill the volume, resulting in vaporization. Also known as cylinder cavitation. "Air" can only enter the cylinder if there is a place of entry in the line conductors, etc, or if the pump is being aerated.

- Typically John Deere does not send high pressure pump oil to 'both sides' of the cylinder. They more often have a regen spool position and/or pilot operated valve that triggers regen, that connects pump outlet to cylinder base end, and reroutes rod end to base end with an orifice and a check valve, instead of allowing rod-oil to return to tank. The resulting pressure drop at the base end causes the oil from the rod end, and the pump outlet to go to the cylinder base end.

That is to say, "Regenerative Oil" from the Rod end, and "Supply Oil" from the Pump are both flowing in to the cylinder base (head) end increasing cylinder speed and preventing cavitation.

The whole spiel about volumes, overpowering, both sides being "pressurized" etc, is categorically incorrect.

The point to remember is, that High Pressure always moves towards low pressure.

I've attached a Schematic from Deere to provide proof.
Text Line Diagram Technical drawing Plan
 

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I do appreciate that the Regen Function description above is being given in Lay terms, however; I would like to point out a few general errors in the description itself.

- There is no 'Air Pocket'. Without the necessary volume of fluid to fill the cylinder base end, the huge pressure drop causes a void to form, which is due to the pressure in the cylinder being below the hydraulic fluid's Vapour pressure. The fluid is stretched to fill the volume, resulting in vaporization. Also known as cylinder cavitation. "Air" can only enter the cylinder if there is a place of entry in the line conductors, etc, or if the pump is being aerated.

- Typically John Deere does not send high pressure pump oil to 'both sides' of the cylinder. They more often have a regen spool position and/or pilot operated valve that triggers regen, that connects pump outlet to cylinder base end, and reroutes rod end to base end with an orifice and a check valve, instead of allowing rod-oil to return to tank. The resulting pressure drop at the base end causes the oil from the rod end, and the pump outlet to go to the cylinder base end.

That is to say, "Regenerative Oil" from the Rod end, and "Supply Oil" from the Pump are both flowing in to the cylinder base (head) end increasing cylinder speed and preventing cavitation.

The whole spiel about volumes, overpowering, both sides being "pressurized" etc, is categorically incorrect.

The point to remember is, that High Pressure always moves towards low pressure.

I've attached a Schematic from Deere to provide proof.
View attachment 73185
If you look at the schematic of a small John Deere tractor, it is quite a bit different than the schematic that you posted.
They really do just put pump oil directly to both sides of the cylinder in the regen position...no orifices, no check valves.
They are not near as fancy as the bigger equipment.
So it really is as the OP stated. The same pressure is applied to both sides, and due to the larger area of the cap end, it overpowers the rod end and the cylinder extends. The fluid is regenerated from the rod end to the cap end back at the valve.
I have many years of experience with the more complex industrial hydraulics where there is a regen valve right on the cylinder so the fluid can go directly from the rod end to the cap end without having to go back through the SCV, they also had counterbalance valves for a more controlled regen because there was large amounts of mass working with gravity.
 

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If you look at the schematic of a small John Deere tractor, it is quite a bit different than the schematic that you posted.
They really do just put pump oil directly to both sides of the cylinder in the regen position...no orifices, no check valves.
That's why I used the words 'Generalized' and 'typically'.

I should like to say. A Pump alone, creates flow, not pressure. Barring that, lets examine this more closely...So as you mentioned, smaller tractors, like a 4000 series, or 110TLB have a bucket dump regen feature, and the technical manual shows no orifice or check valve in the bucket section. I checked. and I agree. And yes, the rod and base end are Teed with pump supply.

•Bucket Spool Section:
The bucket spool (J) section is a four-position, four-way, open-center, lever-operated, self-centering, spool with a regenerative bucket dump detent. The spool section also contains a lift check valve.

Yes, the schematic shows:
Text Floor plan Diagram Font Plan

I would like to point out, that since I work for Deere, I know that Deere often does not bother making their smaller equipment manuals as detailed. But I suspect, if you pulled the bucket spool out of a small tractor, you would see the Spool is cut differently. If you compared the cross section at the A port vs the B port. This is for control of Flow in the system. I'm not talking about metering notches, etc. I'm talking about the amount of spool material removed cross sectionally, by design, for flow characteristics. That would be considered a type of calibrated orifice.

Even if the spool weren't cut differently, I can assure you, that no oil from the pump ever makes it in the cylinder rod end. Yes I understand pascals law, that pressure in a system is exerted equally, in all directions, etc etc. But your forgetting Bernoulli's principle.

Install a gauge on both work ports of a dumping cylinder. Check and record the pressures at slow dump, regen dump, and at dump stalled. And until someone does so, we would only be able to rely on calculated theory to estimate the pressures seen. But again, I can assure you, since the actuator is moving, the pressures are not the same. This is not a static hydraulic circuit. The fluid is flowing through many places where conductor volume changes. Ports, fittings, hoses, spool, etc.

You might say, "But it truly is a closed system" Sure. But don't forget the main relief and anti-cav valve, and the pump in the above 110TLB, are connected to tank.

Now, again, I do agree that because the Base end piston side has a Larger Surface area than the rod side of the piston it will continue to extend if the same hydraulic pressure is applied to them.

You've stated that the
The fluid is regenerated from the rod end to the cap end back at the valve.
.
I never disagreed with this. But this is a moving actuator. The movement causes a pressure drop at the base end and hence movement of oil.

The case from Deere below implicictly states "Regen keeps the bucket cylinders from cavitating by routing oil from the pressure side of the bucket cylinders back to the non-pressure side" and that is for small tractors. Model references at the bottom.

I work for John Deere. I'm a factory trained technician who specializes in Deere Construction and Forestry. I spend everyday, week in and week out, year in and year out working on a wide variety of Deere equipment. In addition. I have several years of Heavy equipment training as well as enough undergraduate chemistry/physics training to comprehend the laws of Science.


Deere said:
Solution Number: 60709

Solution Summary: Bucket moves when trying to back drag. Cavitating bucket cylinders when feather dumping.

Publication Date: Apr 28 2014


--------------------------------------------------------------------------------

**Paper copies of solutions may not be the most current solutions**

Complaint or Symptom :
1. Bucket moves when trying to back drag.

2. Loader bucket flops (has loose movement) after feather dumping heavy loads.

Problem or Situation :
The operator is not clear on which position to move the scv lever while operating in heavy and light loaded applications.

Solution :
Refer to the picture in the attached link 60709_1.jpg while reading the information below.

1. If operating the scv in the regenerative function area (B) while back dragging it will normally want to collapse. If the bucket is light or empty it will normally want to stall out while operating the scv in the regenerative function area (B).

The Regenerative function area (B) should only used for a faster bucket dump cycle with a heavily loaded bucket. Regen keeps the bucket cylinders from cavitating by routing oil from the pressure side of the bucket cylinders back to the non-pressure side, along with incoming pump oil.
To back drag it is recommended to stay in position (A) of the bucket dump function.

If the operator would like to lock the regenerative function out on:

2210 / 4010/ 4100 / 4110 / 4115

Flip the regenerative lockout plate located on the SCV valve over to prohibit movement (Disable) to the full right position.

Lockplate enabled/disabled 60709_2.jpg

4210 / 4310 / 4410 / 4510 / 4610 / 4710 / 31-3720 / 41-4720

Move the SCV lock lever to the top position to enable the regenerative function and to the middle position (Book Icon) to disable the regenerative function.


2. A heavily loaded bucket that is being feather dumped will normally cavitate the bucket cylinders.

Oil is being forced out of the cylinder quicker than it can be filled on the backside. This causes the cylinder to cavitate.

During dumping operations, heavy loads force the return oil out of the bucket cylinder faster than the pressure oil can be supplied. This may cause hydraulic voids, or cavitation, to be created in the head end of the cylinder. As the bucket dumps, it may reach a balance point and hesitate until pressure builds up again in the head end of the cylinder. This cavitation may also allow the bucket cylinders to retract when the operator tries to back blade after dumping heavy loads. Feathering or metering of the control to dump slowly will increase amount of cavitation. Installation of an orifice restrictor (flat face to inside of adapter fitting H82308) in the bucket rod end circuit at coupler may reduce cavitation by restricting oil flow out of the cylinder.

Solution 35065 provides information on installing an orifice.

Additional Information :

--------------------------------------------------------------------------------

4400, 4720, 4500, 4600, 4700, 4010, 4110, 3120, 4210, 4310, 3320, 2210, 4410, 4510, 3520, 4610, 4115, 4710, 3720, 3203, 4100N, 4120, 4320, 4100, 4200, 4520, 4300
 
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I should like to say. A Pump alone, creates flow, not pressure.
True, but that doesn't enter into what the OP is saying


Even if the spool weren't cut differently, I can assure you, that no oil from the pump ever makes it in the cylinder rod end.
True, the cylinder is extending during regen

The case from Deere below implicictly states "Regen keeps the bucket cylinders from cavitating by routing oil from the pressure side of the bucket cylinders back to the non-pressure side" and that is for small tractors. Model references at the bottom.
True, this is what a regen circuit is designed to do.

I work for John Deere. I'm a factory trained technician who specializes in Deere Construction and Forestry. I spend everyday, week in and week out, year in and year out working on a wide variety of Deere equipment. In addition. I have several years of Heavy equipment training as well as enough undergraduate chemistry/physics training to comprehend the laws of Science.
Thank you for weighing in with your experience and your technical expertise. You have an impressive set of credentials. The forum is lucky to have you as a member/contributor. That's what makes this forum great.

I don't think anybody is refuting Pascal's Laws or the Bernoulli principle

I do see what you're saying (I think).
Usually, you are dumping a bucket during regen, so gravity is wanting to extend the cylinder, so the cap end is at a lower pressure than the rod end.
If that weren't the case, say your were pressing the bucket against the ground while in regen, the bucket would still extend, but the pressures would be different.
And of course the force generated by the cylinder would be much less while in regen mode.
 
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Discussion Starter · #14 ·
Here is an EXCELLENT video explanation of how regen works!

 

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Very good video

Here is an EXCELLENT video explanation of how regen works!

That's as clear an explanation as I've ever seen.

Treefarmer
 
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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.
I know this is an almost 8 yr old thread but I just checked my 2018 1025r and it seems the lock lever on my tractor locks the scv completely and not just the regen function. I wonder if I am doing it wrong because I will be plowing with my tractor and would like to lock out regen.
 

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I know this is an almost 8 yr old thread but I just checked my 2018 1025r and it seems the lock lever on my tractor locks the scv completely and not just the regen function. I wonder if I am doing it wrong because I will be plowing with my tractor and would like to lock out regen.
According to the operator's manual that is the correct function of the lock lever. I don't think the 1-series has a regen lockout.
 

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Discussion Starter · #18 ·
According to the operator's manual that is the correct function of the lock lever. I don't think the 1-series has a regen lockout.
Correct, seems as though JD has removed that feature on mY newer models.
 

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Correct, seems as though JD has removed that feature on mY newer models.
Even on tractors like my 2720 that has the regen lockout pin, it's not something that you are going to flip back and forth between jobs. It requires removing the rear tire and moving a hard-to-access bracket on the SCV linkage. In other words, regen would really need to be a problem before you would go this route. Personally, I would just not push the SCV lever to the right as far. :)

I equate it to swapping backhoe hoses to change from ISO to Deere controls.
 
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Even on tractors like my 2720 that has the regen lockout pin, it's not something that you are going to flip back and forth between jobs. It requires removing the rear tire and moving a hard-to-access bracket on the SCV linkage. In other words, regen would really need to be a problem before you would go this route. Personally, I would just not push the SCV lever to the right as far. :)

I equate it to swapping backhoe hoses to change from ISO to Deere controls.



Do you have a parts diagram where I could see where that pin is located? Hoping my 2520 has the same thing...
 
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