Regenerative circuit?

   / Regenerative circuit? #1  

Jay4200

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Nov 23, 2005
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Location
Hudson/Weare, NH
Tractor
L4200GST w/ LA680 & BX2200D w/ LA211
What exactly is a regenerative hydraulic circuit? Is it when two SA pistons have a single 2-way control instead of using a single DA piston? How do they work n' how are they hooked up?

Just attempting to educate myself...

Thanks - JayC
 
   / Regenerative circuit? #2  
What exactly is a regenerative hydraulic circuit? Is it when two SA pistons have a single 2-way control instead of using a single DA piston? How do they work n' how are they hooked up?

Just attempting to educate myself...

Thanks - JayC

Simplified...it is a single rod double action cylinder, that in extend motion get pump pressure on both sides of the piston....the area differential makes net force to extend, but at a speed as a cylinder with the diameter of the actual piston rod.....
regen.jpg


There are way more ways to make regen circuits, even on retract....read here...
 
   / Regenerative circuit? #3  
Regen fills several purposes....

>anti cavitation prevention, helps pump flow to refill capped side...
>quick unload of gravity forced loads, like FEL bucket...
>quick advancement of a hydraulic press cylinder...

There are valves that senses presure and "switch gear" when pressure increases....see SUN Hydraulics
 
   / Regenerative circuit? #4  
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.
 
   / Regenerative circuit? #6  
A couple of negatives to keep in mind about regen use on FEL dump circuits.

Since as Kenny D stated it dumps faster it is also much harder to feather the dump function. Example is trying to keep the loader level while raising.

You also loose dump force. Example: it is much more difficult to tilt the bucket down to dig a little deeper into the ground if it it is already firmly on the ground.

There are other ways to prevent cylinder cavitation from over running loads but this is the least expensive option so.

Roy
 
   / Regenerative circuit? #7  
A couple of negatives to keep in mind about regen use on FEL dump circuits.

Since as Kenny D stated it dumps faster it is also much harder to feather the dump function. Example is trying to keep the loader level while raising.

You also loose dump force. Example: it is much more difficult to tilt the bucket down to dig a little deeper into the ground if it it is already firmly on the ground.

There are other ways to prevent cylinder cavitation from over running loads but this is the least expensive option so.

Roy
Agree there are some negatives....many times we want to utilize the faster motion that the regen allows, but our system is not designed to handle the the multiplied flow that is generated....and huge back pressures are generated...a 4"cylinder with a 2"rod (4:3 ratio) will supply 10 gpm from pump and 30 gpm from the rod side to a total of 40gpm into the capped side....with a regen spool in the control valve, it is a no brainer that back pressure will be an issue, especially when we tend to dimension hoses and control valves for pump flow instead of real flow...
then a inline regen valve placed on the cylinder will be more efficient...

Well dumping (or lowering) a load is still 100% lost potential energy....regen or not doesn't matter

I can add another benefit with regen.....a 6-7 function knuckle boom logging equipment crane is always operated with 3-5 functions simultaneously moving. Pump flow is then many time limited (bottle neck), and regen can support pump to supply fill flow on functions that more or less extend from load of gravity....like stick (2nd boom) in/down and telescope out...
 
   / Regenerative circuit? #9  
How many of you had to look up the word [ eductor ]? Even the spell check hit on it. I have never heard or used it before. It appears to be an injector type unit.
 
 
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