Regenerative splitter valve?

[NSMaple1]

Anybody heard about this new-ish Wallenstein thing?

http://www.wallensteinequipment.com/ca/en/firebolt.aspx

Is this type of valve truly new, and theirs only?

Would make for a pretty good retrofit splitter hop-up, me thinks, maybe - kinda surprised I haven't heard anything about it anywhere else?

 

[muddstopper]

Regen works by suppying oil to both ends of the cyl at the same time. Because the base end of the cyl has more surface area than the rod end, the cyl will extend faster (slam out) than it would normally. Big problem is that regen only works to extend the cyl, not to retract. Also because the base surface area is reduced by the rod surface area, the cyl will exert much less force. Regenerative valves are nothing new, see them on tractor loaders all the time. I have heard of people retro fitting them to log splitters before, but have never actually seen one set up that way. Personally, I dont see any benefit of having one on a log splitter. The only speed gain you would see would be if you where splitting short wood with a long stroke cyl. As soon as the pusher plate contacted the wood, the regen would have to switch to a regular hydraulic configuration or it would not be able to produce enough power to actually split a round. If you have a splitter with a 24in stroke and you are splitting 16in wood, the regen would only work for the first 8 inches of the extend stroke and would not work at all for retracting the cyl. For the first 8 inches of stroke, the cyl would extend very fast until it contacted the round, then it would have to shift to the regular splitting mode and then yo hyd pump would be in the low flow high pressure mode until the wood started to split at which time the pump would shift back to high flow low pressure mode, and if the wodd happened to finish splitting with very little force, the regen valve might shift back into regen mode and give you a little extra speed to finish the split. In that situation the cyl would certainly slam all the way out, but I think the total time save on cyle time would be minimal, and the possibility of having a hand or finger in the wrong place at the sudden acceleration of the cyl, is to great of a risk for me to even want to try using regen on a wood splitter. JMHO.

 

[muddstopper]

When I posted above, I had not looked at the wallenstien splitter. After watching the video, I decidede to add a few more comments about how regen works and were the extra speed actually comes from. A regen valve is designed to divert oil to both ends of a cyl at the same time. While both ends of the cyl will have equal pressure, the base end of cyl has more surface area of the piston that the rod end. The creats an unbalance in force withh the base haveing the more force than the rod end. there fore the oil in the rod end is displaced from the cyl barrel and returned to the base end of the barrel. Therefore you actually have more oil pushing the cyl out than what the pump is produceing. The increase in oil flow is determined by the actuall difference in volume of the opposite ends of the cyl. A cyl bore that has a small dia rod will hold a greater volume of oil that a cyl with a large dia rod. The cyl with the smaller rod will extend, under regen, faster that the same cyl using a larger dia rod simply because the smaller rod cyl has more oil in the barrel. With bigger difference between barrel dia and rod dia, the greater the difference in speed. Under regen the difference is alsoo expressed with a greater difference in force. While the cyl with the smaller rod will extend faster, it will also have less force. The clyl with the larger dia rod will have a slower speed, but also have a greater force. The Wallenstien splitter uses a 4.5in bore cyl and a 13gpm 2stage pump. They dont list the size of the rod on their website. Just looking at the video, the rod looks to be about 2.5in dia. but that is just my guess. this big rod is why the cyt doesnt just slam out when in regen mode. If it had a smaller rod, the speed would increase under regen. to give a little ideal of the difference in speed because of rod size.

I did a little math using the 4.5bore piston x 24in stroke with a 2 in rod, versus a 2.5in rod. With out regen, the cycle time of the cyl with the 2 in rod would be about 13.9sec. With a 2.5 in rod, the cycle time would be about 12.9 sec and increase in speed of 1 full sec. To take this a little further, I decided to compare the times if I chose to use a little bit bigger pump. Using a 16gpm 2 stage pump, the cyl with a 2in rod cycled in 11.2 sec and the 2.5 in rod cycled in 10.5 sec. I did this to demostrate the difference that oil flow has on cycle times. Of course, everybody know if you can supply more oil flow, you can increase speed. This is what regen does to a cyl, it combines the oil flow from the rod end of the cyl with the pump flow to increase the speed of the extention of the cyl. Because regen will never work on retraction of the cyl, just no way to overcome the difference in piston surface area from base end and rod end of the cyl, the only time regen is of any benefit is extention. On retraction, you are still stuck with the 13gpm flow of your 2 stage pump. JMO, the best way to increase cyl speed is still to increase oil flow. With more oil flow, you have the beneifit of haveing the smae amount of flow retracting the cyl as you have extending it. There is also the issue of the control valve with regen. If you watch the video, the operator has to reposition the control valve manually to swith from regen mode to normal mode, it only takes a fraction of a sec to do this, but there is that pause in cylce that reduces cyle times. I didnt do the math to see just how much oil flow is increased with the use of regen because, I just got lazy, I already knew the increase is the volume of oil contained in the rod end of the cyl barrel and with the big rod they are using, there isnt much oil there. I also already knew that the big rod combined with the small volume of oil is why the cyl doesnt just slam out on extention. If you watched the video of the comparison of their new splitter w/regen, versus their older splitter without regen, you will noticed they only compared extension speed, and not retraction. Not knowing anything about the other splitter configuration, one could only guess that it had a similar size cyl and pump and retraction speed would be about the same for either cyl

I think Wallenstiend did a good job controlling the cyl speed with their combination of large rod size and small volume pump. One way to control cost is by maximizing speed and power using the least costly method. Larger pumps and bigger hp cost more. I still think it is a compromise of cost versus performance.