Can someone explain regen???...Etc.

[Inky05]

When I look at the schematic for this valve it looks like "P" is connected to "A" AND "B"...
I would think the cylinder would stop due to pressure equalization...

What am I missing????

Also I'm not clear on power beyond... Why can't the "T" port be plumbed to the next valve in series to accomplish the same thing?

Sorry so lame...:ashamed:

 

[oldnslo]

When I look at the schematic for this valve it looks like "P" is connected to "A" AND "B"...
I would think the cylinder would stop due to pressure equalization...

What am I missing????

Also I'm not clear on power beyond... Why can't the "T" port be plumbed to the next valve in series to accomplish the same thing?

Sorry so lame...:ashamed:

Regenerative flow systems: This is based on the difference in areas between the rod end and cap end. I.e. the rod area itself it what allows the cylinder to extend. Most regenerative cylinders usually have a cylinder ratio of around 2:1 example. 6" bore cylinder with a 4 " rod would give a cap end area of 28.27 sq inches while the rod end area is 15.7 sq inches.
The 4' rod area of 12.56 sq inches is what allows the cylinder to extend.

Power beyond: Most directional valves have the "T" port tied common to the centering spring chamber. This spring chamber housing typically is not capable of handling high pressure.

Does this make sense???

Roy

 

[Inky05]

Regenerative flow systems: This is based on the difference in areas between the rod end and cap end. I.e. the rod area itself it what allows the cylinder to extend. Most regenerative cylinders usually have a cylinder ratio of around 2:1 example. 6" bore cylinder with a 4 " rod would give a cap end area of 28.27 sq inches while the rod end area is 15.7 sq inches.
The 4' rod area of 12.56 sq inches is what allows the cylinder to extend.

I just don't understand how this is faster than full pressure on one side and no pressure on the other(or light restriction)...

although as I think about it... it is higher flow to the head end... so I guess ... maybe...
...but it would be a compromise in pressure(force) equal to the advantage in speed... Right?

 

[Inky05]

Power beyond: Most directional valves have the "T" port tied common to the centering spring chamber. This spring chamber housing typically is not capable of handling high pressure.

I did not know that... I thought the spring was just another operator at the other end of the spool... sealed off from the fluid just like the solenoid or lever at the other end

 

[oldnslo]

I just don't understand how this is faster than full pressure on one side and no pressure on the other(or light restriction)...

although as I think about it... it is higher flow to the head end... so I guess ... maybe...
...but it would be a compromise in pressure(force) equal to the advantage in speed... Right?

Inky,
you sacrifice force for speed with regen circuits.

Using the example above of 6" bore with 4" rod the cylinder will travel about the same speed in both directions and have close to equal force in both directions also. Reason is that ALL of the rod end flow is being directed back to the cap end along with the pump inlet flow. So in essence the pump flow is just filling the void created by the rod or the rod area of 12.56.

On a lot of industrial systems they will have some form of switch that will shift the system from regen to normal once a certain condition is met.

An example: Large card board baleing machine. The cylinder will extend in regen until a preset pressure is reached and then switch over to slow speed high force to finish compressing the card board. With large rod diameter the cylinder will retact faster with less pump flow. This helps save time which equals money. Also reduces the size of pump / motor required.

From experience: (read bad experience) Valves need to be sized to handle the increased flow rate.

These calculations are based on the cylinder having 120" stroke and 20 GPM pump. When extending you would have 25 GPM "return" flow from the rod end of the cylinder this flow must pass through your valve and then is combined with the 20 GPM for a total of 45 GPM going into the cap end of the cylinder.

The "Time" is for cylinder stroke.

Velocity inches / sec time retun flow rate
extend velocity 2.72 44.06 25
regen velocity 6.13 19.58
retract velocity 4.90 24.48 36.00

Does this help explain the concept a little better?

Roy

 

[mmurphy]

Inky, just think about how the rod end has a certain amount of fluid in it. In REGEN you are taking that fluid and pushing it to the other end plus the fluid that (with valve actuated) the pump at what ever galons per minute is going into moving the cylinder. A 2 to 1 ratio you will have half the force (power) to that cylinder. Drop out of regen and you are back to full force. Remember a 2 to 1 cylinder has twice the area for the psi to work on opposite end (blind end) to the rod end, so there for it will work only in 1 direction. There is valves made for this and or a simple add in to a circuit can be done.

 

[J_J]

A simple answer on regen is that the GPM's to the base end, is about doubled, increasing speed of extending, and the pressure is reduced about 1/2, therefore, less force in regen.

 

[kennyd]

Here is a very good description of regen by a former contributor here at TBN: Regen

Here is another from an internet link: http://www.hwhcorp.com/ml37939.pdf

 

[AKKAMAAN]

Woops....now we gotta straighten this "regen" thing out......


We start real simple...


"Regen" means REGENenerative, and means the we regenerate the fluid from the rod side, of the duoble action cylinder piston, back to the capped side of the piston...As highlighted, regen requires a double action cylinder, with a rod coming out at one (1) end of the cylinder.

What regen do is that, when extending cylinder, it connects both ports on the cylinder to each other. At regen function, the pressure will equalize on both sides of the piston, and the net force will be from the cross areaof the piston rod . That means, because the rod diameter is smaller than the cylinder bore, it will take less pump flow to move the cylinder, and we get a faster speed, but lower pushing force.
A cylinder with rod diameter 50% (1/2) of the bore diameter, will get a 1/4 of the force but 4 times the speed, at regen.

There are basically, three different ways to do this....

#1>> the regen circuit can be closed with the a 4th position on the controlvalve, CV. se Prince MODEL LSR-3060 RAPID EXTEND LOG SPLITTER VALVE

#2>> the regen circuit can be closed with a "valve" between the CV and the cylinder....often a pressure sensitive valve that automatically shift to regen at low pressure. se Sun hydraulics pressure sensitive regen valve

#3>> the regen circuit can be closed with a valve built into the cylinder itself


At all three of above options, the rod side port on the valve is closed to tank, when we operate cylinder extendtion. That takes a special spool in the valve.

#1 and #3 wont allow and flow back to tank. At option #2, there are valves available, that drains a part of the fluid to tank, depending on pressure (horse power regulated).


A regen cylinder does not change its function on retract, only on extend.

Basically the regen function is made to help the pump with flow, when no pressure is needed....

An example...

A grapple loader crane have a teleskopic extention that usually is used to "reach out" for logs. Most often with help of gravity. There is no linkage that leverage for higher motion speed, the grapple will move at the same speed as the cylinder. To make this extention faster, regen is used, and also pump flow can be used for other simultainously operated functions. Watch this video clip...

 

[J_J]

Just what needed straightened out? What did you say different?

 

[AKKAMAAN]

Just what needed straightened out? What did you say different?

Sorry J_J I didn't want point you out, you did it your self....

There is some very good posts about this....I liked that old thread Kennyd referred to....Oldnslo and mmurphy gave some graet input, and I just wanted to give my input....and your are "about" right about the "doubled" flow to the capped end.....

But I just cant agree with this...QUOTE:"....the pressure is reduced about 1/2, therefore, less force in regen..."


The pressure wont be halfed when regen, it will actually be higher than no-regen....because the net effective cylinder area will be the same as the rod area...The less available pushing force will be caused by the reduced, net effective, piston area (rod cross area) AND the PRV setting.

if rod diameter is 50% (1/2) of the bore, pressure will become 4 times higher to move the load.... 33% (1/3) >>9 times, 70.8%(2:1 ratio)>>2times ...etc etc

regen at 2:1 ratio, will give us a cylinder with the same force and the same speed in both extend retract...good to think about when designing a one cylinder steering......

I have had hydraulic students in front of me for 20+ years, so I am used to, listen with "the students ear".... and that means that if I am are trying to explain/teach something for someone, that do not know anything in the subject...I only get ONE chance to say it right....unless I correct my self....

 

[greasemonkeyok]

Question: when you are adding a top link for a BB, should the cap end or the rod end be connected to the tractor side?

 

[AKKAMAAN]

Question: when you are adding a top link for a BB, should the cap end or the rod end be connected to the tractor side?

I would kep the capped end to the tractor, to avoid that oil lines moves when cylinder is moving. That will prevent/limit abrasion and wear on hoses. Hoses usually also can be at shortest possible lenght....

 

[kennyd]

Question: when you are adding a top link for a BB, should the cap end or the rod end be connected to the tractor side?

I would kep the capped end to the tractor, to avoid that oil lines moves when cylinder is moving. That will prevent/limit abrasion and wear on hoses. Hoses usually also can be at shortest possible lenght....

AK has it right...the rod on the implement side.

Not sure how that is related to the topic though:confused2:

 

[greasemonkeyok]

"Not sure how that is related to the topic though" You are correct in that it is a bit of a hijack, but thanks for responding anyway.

The above discussion made me think about the fact that pressure on the plunger from the cap side may be more efficient in raising the BB than pressure on the rod side - from a power standpoint I guess it is a matter of whether you want to pull up with more force or push down with more force.

 

[SPYDERLK]

"Not sure how that is related to the topic though" You are correct in that it is a bit of a hijack, but thanks for responding anyway.

The above discussion made me think about the fact that pressure on the plunger from the cap side may be more efficient in raising the BB than pressure on the rod side - from a power standpoint I guess it is a matter of whether you want to pull up with more force or push down with more force.

no matter which way you mount it the cyl has to pull to shorten. A cyl strength is not used optimally in a toplink.
larry