Wood splitter hydraulic question?

[lennyzx11]

I have added a 2nd prince valve to my wood splitter to run a log lift. Both are same valve.
They are connected pump>1in>1out>2in>2out>tank.

The puzzling thing is when I first nudge the #2 valve, the lift seem to power(not coast) down slightly. I give the handle a bit more movement and it responds as expected going up. Valve 1(splitter) is in neutral.

Both valves are connected to DA cylinders.
I’m not sure why that bit of drop occurs when #2 is cracked to go UP.

At first I thought maybe air in cylinder 2 from the install but after exercising it through a couple of bucket loads of wood, it still does it.

Ideas?

Lenny

 

[Dave M7040]

I have added a 2nd prince valve to my wood splitter to run a log lift. Both are same valve.
They are connected pump>1in>1out>2in>2out>tank.

The puzzling thing is when I first nudge the #2 valve, the lift seem to power(not coast) down slightly. I give the handle a bit more movement and it responds as expected going up. Valve 1(splitter) is in neutral.

Both valves are connected to DA cylinders.
I’m not sure why that bit of drop occurs when #2 is cracked to go UP.

At first I thought maybe air in cylinder 2 from the install but after exercising it through a couple of bucket loads of wood, it still does it.

Ideas?

Lenny

Your plumbing is completely wrong!!!!

First, your first valve in line needs to have a power beyond circuit. This is usually an optional sleeve or plug which you buy and install. Since your latest valve is the newest, see if you can buy a power beyond kit for it.

The power beyond option is to feed or provide an IN or Pump port for the second valve in line.

You should never use an OUT port of one valve to feed another. OUT or TANK ports are only designed to handle around 450 psi and when the second valve calls for pressure the first valve's pressure on its TANK port will greatly exceed its rated pressure.

Dave M7040

 

[LD1]

If you are trying to feather the raise....it won't develop enough pressure to overcome gravity acting on the cylinder without more flow.

Loaders have anti-drop valves to prevent such a thing from happening when trying to make precise movements.

Also, the valves in series like that isn't a good idea. You really need a power beyond first valve to feed the second valve. Or should have gotten a 2-spool valve to handle both rather than adding a single to the system.

But regarding the dropping....you'd be better off either using a restrictor fitting with orifice or even a flow control valve to Taylor the speed to your liking. Then you don't have to easily feather the valve

 

[WranglerX]

According to this site it would appear there is no PB (power beyond) capabilities if this is correct valve...

Model LS3000 Log Splitter

Model LS3000 Log Splitter valve

www.princehyd.com

http://www.princehyd.com/Portals/0/valves/ValvesLsRD25.pdf?020820160708

 

[lennyzx11]

I was afraid of that. I am getting a 2 valve block but also had read numerous accounts of how it worked fine.

Dave I believe you. But it doesn’t seem like the valve itself would have a lesser pressure rating on the Out port. The pump is designed to put out 2500 psi. I see where the OUT fitting and Line to tank is rated only for tank pressures but I installed the nipple between in and out as a 6000 psi hydraulic fitting.
Are you positive on that? You’ve given me great advice over the years so I trust you completely but don’t see how.

 

[LD1]

The tank passages within the valve casting are nearer to the outside...and often much thinner than the pressure port passages.

The valve itself is not rated to have pressure on the tank port. If you do....you run the risk of cracking the housing....or blowing the end spools out of the valve and have it constantly leak.

It all has to do with the inner construction of the valve and is not something you can see.

A log lift....depending on your geometry.....may not take much more than 400psi to operate. So people may get lucky. Still doesn't make it right. And if you ever deadhead the cylinder you are spiking the pressure.

The simplest thing is to get a 2-spool loader valve. They usually have load-checks. Which the dropping of your lift table when trying to feather slowly was the reason for your post in the first place

 

[Tx Jim]

Dave M7040
Do you know when power beyond was introduced to farm equipment hyd systems? I don't remember PBY being on farm equipment when I was employed by a JD dealer '66-'87 BUT I was more involved with closed-center hyd systems than open-center hyd's. I've seen several older tractors with single spool valves connected in series to form dual/triple spool valves with no PBY similar to how Lenny attached his valve. I also agree with LD1 & think a check valve will solve Lenny's hyd problem

 

[RodRocket]

Firstly, if you want to add another valve bank inline with the first valve bank, the first valve bank must be fitted with a power-beyond sleeve, and the first valve bank must have an integral relief valve built in or one connected externally to the "P" line correctly.

Why both components?
The tank port of the first valve bank must be free to allow the relief valve to relieve to tank without back pressure, and to allow the returning oil from any operating cylinder connected to the first valve bank to return to tank also.

Now the power beyond sleeve.
This externally fitted sleeve in the first valve bank virtually allows high pressure oil from the pump to continue directly through to the second valve bank without interfering with any relief or returning cylinder oil in the first valve bank, freely able to go back to tank via the alternate "T" port.

Internal load-holding valve.
Some cheap valve banks do not have a load-holding check valve in the internal high pressure gallery, and as such, during the initial shifting of the spool, oil in this HP gallery is momentarily allowed to leak back to tank with the returning oil. This is why the load may drop a little before it is raised.

 

[Fxfymn413]

I have used the same set up you have for the past ten or more years on my splitter and it works just fine as long as you do not try to use both functions at the same time. As stated when you try to feather the load gravity will take over until you apply enough hydraulic pressure to compensate for the load.

For those folks who say it will not work I just finished splitting three cords of oak yesterday.

 

[lennyzx11]

I am waiting on a AutoCycle valve with Power Beyond that’s on perpetual back order to install as Valve1.

This is more a case of some people says it works fine and some doesn’t. I had the pieces, the shop was warm from the wood stove, so I wanted to see for myself.

I do understand now that the tank passages may be milled to not have the same bursting strengths now per explanations. Thank you.

And a check valve in log lift plumbing would compensate for the gravity drop.

Thanks for all the education. As I said I don’t intentionally want to build something that will damage or hurt somebody but want to understand when a lot of “very” knowledgeable people are opposed on views on it works, not safe, been that way forever, etc…

Lenny

 

[Leejohn]

Sounds like to me his valve is not returning to center, check springs.

 

[Tx Jim]

RodRocket
I ask you same question I asked Dave M7040. Do you know what time frame(year) the concept of power beyond was introduced? I sure don't remember PBY being in use in use 40 or 50 yrs ago.
Thanks, Jim

 

[Dave M7040]

I was afraid of that. I am getting a 2 valve block but also had read numerous accounts of how it worked fine.

Dave I believe you. But it doesn’t seem like the valve itself would have a lesser pressure rating on the Out port. The pump is designed to put out 2500 psi. I see where the OUT fitting and Line to tank is rated only for tank pressures but I installed the nipple between in and out as a 6000 psi hydraulic fitting.
Are you positive on that? You’ve given me great advice over the years so I trust you completely but don’t see how.

I was afraid of that. I am getting a 2 valve block but also had read numerous accounts of how it worked fine.

Dave I believe you. But it doesn’t seem like the valve itself would have a lesser pressure rating on the Out port. The pump is designed to put out 2500 psi. I see where the OUT fitting and Line to tank is rated only for tank pressures but I installed the nipple between in and out as a 6000 psi hydraulic fitting.
Are you positive on that? You’ve given me great advice over the years so I trust you completely but don’t see how.

I regret that my advice is correct especially with the valves you are working with.

I looked over the spec's for the valve you posted. The spec's are even worse than I expected with a max tank port pressure of 150 psi. Normally I see 450 psi as a valve's tank port spec..

When your second valve controlled cylinder hits the end of its stroke and the pressure spikes, your fist valve may just split,

Hydraulic oil shooting out small cracks is very dangerous and can be injected right thru your skin.

Consider putting one of your two valves on the shelf waiting for another project and buy a valve which can have PB. You do not need a valve rated for 25 gpm.

In answer to the question when did PB first appear. I do not know. In my case what has happened is that my knowledge/experience has grown.
Further, engineering design practices are much more refined and valves are able to be designed just strong enough to meet published spec's.

In the 1960's all products were built with high safety factors as this was cheaper than spending countless design hours pushing the valve design to the limit.

Now weight is a big consideration and if a few ounces can be shaved off a product, that will drive the design.

Dave M7040

 

[LD1]

Alot of older tractors had to add a pump on the front of the crank for a loader. Therefore the loader valve was the only valve in that circuit.

Modern stuff is different and built with a loader in mind from the get go. Not as an afterthought.

That in combination with most older deeres being closed center.

 

[Fxfymn413]

And a check valve in log lift plumbing would compensate for the gravity drop.

It is a double acting cylinder so a check valve will keep it from working since oil must return to the valve from the non-pressurized side of the cylinder.