Beefie
Addicted to ArboristSite
Some people are passing pure horse hockey by saying it is not acceptable, or it is immoral or anything other than plain OK to place open center valves in series or "stacked" in this application ( sorry for the rant, second time this week for this discussion). You can go look at any older back hoe, grader etc that was built back when such equipment had gear pumps and all the valves were open center and made to stack with long through bolts. Want to have 50 valves? just need to find long enough bolts. I have worked on this stuff for a living for 35 of my 52 years.
With the single valves like you have stacking is a simple matter of a pipe nipple long enough to give clearance to turn, dope the threads and screw them together out port to in port just like you said. The only way you can have excess pressures as some claim is if you fail to properly set the reliefs in the valves and then your going to have it no matter if you pull one valve at once or twenty one. Each open center valve has a relief for that circuit. If you pull two or more valves at once the lowest set relief will control system PSI. period end of discussion.
Also BS is "you cant run two functions at once with stacked valves". Want to see my splitter do it? Seldom will you pull two valves at once on a splitter anyway unless you have a good helper and if so he better be both good and attentive. Want to get hurt spltting wood? get lots off things moving and two guys pulling levers. I have two darned good helpers and it is taboo for morethan one guy to be yanking levers.
Power beyond is needed in systems much more complex in flows and performance than wood splitters. To understand Power beyond you need to understand open center and closed center valves. Open center means that when in the hold position oil flows unrestricted from the in port to the out port Closed center means oil is topped from flowing when valve is in the center. Obviously you cannot stop the oil from flowing when you have a simple gear or vane pump as used on our splitters. The oil flow is either is used for work or goes straight through the valve(s) and back to the tank. Back before the term power beyond was invented we did the same thing with what is called a "convertible" valves. An open center convertible valve was made closed center by installing a plug in the spool so oil could not flow through it when centered. These were used in systems that required that type of valve (another long winded discussion) Now a days they are still called convert a valves, untill placed in a "power beyond" situation. Power beyond is nothing new, it just a modern term for placing two or more control valves in parellel flows instead of series. But back to a splitting ciruit, converting valve 1 in the flows to closed center is what the power beyond conversion is in the Prince flow example from prior poster (I have that same valve) The second valve must then be open center. If you wish to go that route and want better instructions for plumbing Illbe glad to try and help you out.
I guess I have said enough, LOL
Pic is my splitter with 4 valves stacked or in series . First is a 2 spool Prince Auto cycle valve, then the wedge lift, then the log lift which are just ordinary “log splitter” valves sold at many places. Wont guide the space shuttle, but doesn’t need to.
<IMG SRC= http://i30.tinypic.com/2h6h8q0.jpg>
Good post Butch. I thought that you were just tired and not thinking and typing at the same time It was posted @ midnight. Very good explanation of the hydraulics. One more person I can right down for info when I go to build my own splitter.
Is your splitter PTO driven, how big of a pump are you running, single stage or dual stage how big is the ram on the splitter.
Thanks
Beefie