Poll....Splitter valve and power beyond

[AKKAMAAN]

Here is a little brain teaser for you all...

Sven (Swede) planning to build a log splitter. Eventually he, later on, want to add a log lift and maybe a hydraulic 4 way wedge adjuster. He do not want to plumb the extra 2-spool valve at this moment.
Sven know he will have to do a power beyond addition, but he is not sure if the splitter valve should be upstream or down stream the additional 2-spool valve.


A:
If the splitter valve is placed up stream, he will need a splitter valve that is power beyond, PB, capable.

B:
If he choose to have the splitter valve down stream, his additional 2-spool valve need to be power beyond, PB, capable.

C:
It does not matter if splitter valve is up stream or down stream the additional 2-spool valve.

How should he best plan for the next addition of valves? A, B or C??

Please feel free to motivate your vote!

 

[AKKAMAAN]

aw come on....

13 days left on this challenging poll....LOL....are all of you guys studying for a hydraulic engineer degree before voting??? :help::angry2::deadhorse::hmm3grin2orange: ???

 

[kevin j]

Per, good question, will be interesting how it unfolds. kcj



aw come on....

 

[Aaron441]

Why go power beyond? Just plumb the other 2 valves in series with the first. If it's open center you can really only operate one function at a time anyway. Just make sure the other 2 valves are the same size as the first so it does not choke the oil flow.

 

[AKKAMAAN]

Why go power beyond? Just plumb the other 2 valves in series with the first. If it's open center you can really only operate one function at a time anyway. Just make sure the other 2 valves are the same size as the first so it does not choke the oil flow.

Thank you Aaron441, for your reply! Good post, which I truly needed to turn up the heat in the debate....LOL....
I'll let it sit for a day, to see if someone wants to reply to you...
BTW, I have a question to you....If we plumb this "your way", in which of the two control valve units, do you prefer to have a pressure relief valve?? The 1st, upstream one, the downstream one or both?

 

[komatsuvarna]

The splitter valve would need to be down stream of the other 2 proposed valves. Or, thats the way I would do it......I think

 

[brisawyer]

I would go main cyl then accy cyls downstream. I dont think it would matter much unless you plan on operating more than 1 function at a time thenyou can get into some flow issues and pressure intinsification issues. I would go with relief on both.

 

[Aaron441]

I agree.

 

[Deereman76]

I concurr. Pressure relief on each valve.

 

[AKKAMAAN]

Why go power beyond? Just plumb the other 2 valves in series with the first. If it's open center you can really only operate one function at a time anyway. Just make sure the other 2 valves are the same size as the first so it does not choke the oil flow.

There are a few very good reasons NOT to use your way to connect a second valve down stream.

1. When downstream valve direct the flow and stalls an actuator, The return cores in the upstream valve get pressurized with MAX pressure. That will preety quick blow the spool seals (o-rings).

2. Most valve bodies, are not rated for more than about 700-1000 psi in the return core. Excessive pressure will potentially crack the valve body.

3. Back pressure in the return core will disable the function of the pressure relief valve, PRV. If valve spring is set at 2500psi, and back pressure is 2000 psi, the total PRV setting will be 4500psi. (Then you really need an additional PRV in the down stream control valve....)

There is no other safe option than a Power Beyond connection, unless we have a closed center system with constant pressure.

 

[flxblx]

i favor

A:
If the splitter valve is placed up stream, he will need a splitter valve that is power beyond, PB, capable.

I am not an engineer, but this option seems logical to me.

 

[AKKAMAAN]

i favor

A:
If the splitter valve is placed up stream, he will need a splitter valve that is power beyond, PB, capable.

I am not an engineer, but this option seems logical to me.

Thank you for your post!
Why would it be more "logical" having the splitter valve PB-capable upstream, than using a PB-capable 2-spool valve for the additional cylinders, and havin the splitter valve downstream?

 

[flxblx]

Thank you for your post!
Why would it be more "logical" having the splitter valve PB-capable upstream, than using a PB-capable 2-spool valve for the additional cylinders, and havin the splitter valve downstream?

I tend to build projects in stages.
Make sure the splitter itself works. Use it for maybe a year or 2 then come back and add on a log-lift or additional cylinders. None of the add-ons would have the flow requirements; or they might need restrictors to slow cylinder movement.

 

[2FatGuys]

A more important question is: What is the capacity of the pump and what are the cylinder sizes?

When I was "engineering" my splitter build, I worked everything around a 28gpm pump. What I found while doing the math was that the 10x2 cylinder for the log lift would launch the log rather than lift it. 28gpm is WAY too much to try to flow through a lift or adjustable wedge or stabilizer foot. I opted to create two separate circuits, one for splitting and one for everything else. I used a "conrolled flow diverter" valve and send 8gpm to the accessories and the rest to the spltter ram.

 

[kevin j]

I opted to create two separate circuits, one for splitting and one for everything else. I used a "conrolled flow diverter" valve and send 8gpm to the accessories and the rest to the spltter ram.


Not too big of a bunny trail, but you have raised a good point about making it into two circuits: Do you miss the 8 gpm or is everything ok for speed? How about heat?

If you use the priority divider to take off the 8 gpm, then use a power beyond valve for the accessories, you can take the power beyond output port flow, (the 8 gpm) back to a tee in the main cylinder circuit.
-You will gain back the flow and have the full 28 for the cylinder if not using any acessories. That helps speeds,which may or may not matter.

-Probably more important, it would reduce the heat/power losses of the 8 gpm going out the priority divider when the cylinder is working hard but 8 gpm accessory load is not working at all.

A priority divider basically watches the 8 gpm side and throttles the two ports to hold that 8 gpm steady. If the accessory is loaded, but the remaining 20 gpm is not, it will throttle the 20 gpm to create a pressure drop. That 20 gpm, throttled at whatever load the 8 gpm requires, is wasted as heat. Probably not an issue as the accessory is not used much.

However, the other way, every cylinder cycle the 8 gpm will be wasted energy as heat at the cylinder load pressure. Since that happens every single cycle, it might be significant heat buildup if the cylinder is cycling fairly steadily.

kcj

 

[AKKAMAAN]

ooops....now we are getting off track a little, but thats OK...

I am not sure if I like the flow divider alt priority valve idea...It would just create extra heat....and also limit cycle time for the splitter cylinder....

I understand that you will need it if you have to operate the splitter cylinder simultaneously with the other two functions...

The wedge adjuster do not require any significant force, flow and no significant structural stability, so that one can be operated with a minimum flow (0.1gpm for a 1" bore)
The log lift will only be operated each time a BIG log, an over weight log have to be split....

My point is that since the splitter cylinder, by far is the most frequent and flow consuming actuator, and the other two are not very frequent, I would not install a flow divider or priority valve, that will create heat 90% of the time....

Then I'd rather design with two separate pump circuits, or even better, a 3-spool mono block valve that allows simultaneous operation....

 

[AKKAMAAN]

I tend to build projects in stages.
Make sure the splitter itself works. Use it for maybe a year or 2 then come back and add on a log-lift or additional cylinders. None of the add-ons would have the flow requirements; or they might need restrictors to slow cylinder movement.

Fair enough...I can see your point....when adding the 2-spool valve you do not have to worry about rebuilding the pump supply lines, which are the most costly (3/4" 4-wire??)


Here is my HINT for today!!
There is another issue that can be good to consider when deciding if splitter valve or 2-spool valve should be PB capable......Creation of HEAT!!

 

[AKKAMAAN]

A more important question is: What is the capacity of the pump and what are the cylinder sizes?

When I was "engineering" my splitter build, I worked everything around a 28gpm pump. What I found while doing the math was that the 10x2 cylinder for the log lift would launch the log rather than lift it. 28gpm is WAY too much to try to flow through a lift or adjustable wedge or stabilizer foot. I opted to create two separate circuits, one for splitting and one for everything else. I used a "conrolled flow diverter" valve and send 8gpm to the accessories and the rest to the spltter ram.

The problem with diverting (feathering) a low flow to work port when the pump is delivering big flow, is how to precisely feather the valve. Especially since there is barely no load pressure on the cylinder.
With an adjustable flow control valve on the hose to that 2" log lift cylinder, you can get better speed control. It will of course create some extra heat, but only when the log lift control valve is operated...

 

[AKKAMAAN]

Just guessing here but it seems to me the cylinder valve should be the first of the two and of course be power beyond. I'm thinking there would be less resistance in the plumbing when the ram is under full push.

How feasible would it be to run a power steering pump off of the flywheel side of the engine to power aux functions? Seems aux would be real low flow needs....after all.......a log lift doesn't have to flip the chunk in the air. I don't like the flow divider idea but hyd power has to come from somewhere for aux.

Great thread!

Thanks for reply...
Hint number 2...
Imagine up the entire plumbing (make a simple drawing if needed) of a PB system, solution is found in the return part of the system

 

[gpsman007]

Good luck finding a log splitter valve with PB