Valve Spool, Control Valve questions

[woodlandfarms]

WOW, Guys... Thank you very much for all the info.

Akka, I am so glad you offered to drive down and help me with all my hydraulics project ;-)

JJ, Wayne, DFK As always, thank you very much.

My dream would be to do as JJ suggests, just replace the 3 spool system with a 4 spool system. I have two issues with this, the biggest being that I am pretty sure I do not have the room to cut a new hole for the additional controls given the limited real estate to the right of the steering wheel. Second is I have no clue what type of control would work there. I would assume that in this project the hoses I have would not be long enough and I would have to buy new hoses all around.

Also, none of the spools I see have the handles vertical. I am sure I am missing something here....

So I have 3 projects I plan to build this summer. The new grapple is for real, the post hole digger is a hope, and the stump grinder is a dream.

Akka, you said something that I need clarification on. Going to building a stump grinder or a post hole digger. These would be powered by my PTO circuit. (PTO's on PT tractors are located in the front and are hydraulic 18GPM at 3100PSI for my machine). In building the Post Hole digger, would I need to plumb some sort of "motor spool" bypass as the PTO is solenoid operated and the hoses really flex when you turn them on and off. I am thinking about motor shock. If so, what would that circuit look like.

Thanks again guys. I do love learning!

Carl

 

[J_J]

Carl, if you already using the 90 in mower, then the solenoid must be a motor spool valve, but you can always add a valve like the below valve, across the motor, to protect it even more. Any shock, or QD separation, stump, etc, the fluid will bypass to the input of the motor. This is a double cushion/relief valve in case you might want to run the motor in reverse, as in post hole digging. The link is a double valve, and one picture is a single valve, and the other one is a double valve.

https://www.surpluscenter.com/item.asp?UID=1208011711415686&item=9-4019-75-H&catname=hydraulic

 

[AKKAMAAN]

A motor spool valve has its special feature in neutral position. If we go back to a regular spool for a double acting actuator (cylinder), that spool keeps both work ports closed in neutral. The actuator can not move when valve is in neutral. Many hydraulic motor applications require the motor to be "unlocked" when control valve is in neutral. A hydraulic wire winch is an example, it will need a spool for bi directional motor control, but with valve in neutral, we might want to be able to pull out the wire by hand, or roll it back on to the drum by hand. Then the motor have to be "unlocked" in neutral. That is made by using a "motor spool" in the valve. With a one directional motor this can be solved with a check valve between the two work ports.
Such check valve is also used to let a motor, with inertia on the shaft, slow down by it self when control valve, suddenly, is in put into neutral. Other wise this rotating inertia will create a "pressure pump" of the motor, and oil wont have any where to go. An example could be a large diameter, heavy mass, circular saw.

 

[J_J]

Carl, this valve from Baileynet.com will give you all the control you need for the lift, tilt, and/or grapple. Any hyd motor function should be handled by the solenoid control you are using now for thr PTO. Should you want to reverse the motor, just switch the QD's for the hyd motor, or switch on the back of the valve.

As far as room for the valve, ask the guys at Baileynet.com for the dimensions, and I believe it will fit in the same space as your other valve, and will allow you to control everything from a central point.

Directional Control Valves 220-951 Detailed Information

 

[AKKAMAAN]

Akka, you said something that I need clarification on. Going to building a stump grinder or a post hole digger. These would be powered by my PTO circuit. (PTO's on PT tractors are located in the front and are hydraulic 18GPM at 3100PSI for my machine). In building the Post Hole digger, would I need to plumb some sort of "motor spool" bypass as the PTO is solenoid operated and the hoses really flex when you turn them on and off. I am thinking about motor shock. If so, what would that circuit look like.

Thanks again guys. I do love learning!

Carl

You are welcome Carl.....I'm am learning a lot too...

I am not 100% sure I get you right on this....any,thing, motor driven with low rpm's and smaller diameter "tool", do not create that much "fly wheel" inertia....and will probobly stop by it self i a second or so...with just a smaller energy "spike"... You can get away with an anti-cavitation check valve....

 

[AKKAMAAN]

Akka, I am so glad you offered to drive down and help me with all my hydraulics project ;-)

I'll be in San Diego for a week in March......

 

[woodlandfarms]

Wow guys, again, eternally grateful for the education..

JJ, look at the photo of the top of my PT where the control arm comes up. The lift arms are welded in the same area, so I am not sure if cutting that area open would be a wise idea. Your thoughts?

 

[dfkrug]

A log splitter valve is a control valve, often with some extra features like auto cycle and/or detent. log splitter valves are hand operated, and they direct a flow, that is "proportional" to how much you move the spool....

I think it is important not to confuse the issue. We commonly "feather"
our mechanically-operated spool valves when we have more than one
connected to the same single-pump circuit. In no way is it "proportional"
control, which implies a predictable (probably linear) relationship between
control input and flow volume. We get this with electrically-controlled
valves, and your explanation there is good.

 

[AKKAMAAN]

I think it is important not to confuse the issue. We commonly "feather"
our mechanically-operated spool valves when we have more than one
connected to the same single-pump circuit. In no way is it "proportional"
control, which implies a predictable (probably linear) relationship between
control input and flow volume. We get this with electrically-controlled
valves, and your explanation there is good.

Thank You dfkrug!! You are right, I was not enough careful in my explanation here..

For me it is NOT the flow to port that is proportional.....It is the movement of the spool that is proportional.....And a mechanichally operated valve then is proportional in that meaning.
Linearity on proportional servo valves is rare. The same when you use servo hydraulic. The main reason for non linearity is that the servo force works against the spring force (spring that center the valve), and the spring force is seldom linear when compressed. A spring is some what progressive.

A proportional flow out put, requires a pressure compensation system.
Compensation will depend on load pressure and supply pressure, which is above what we are dealing with here I assume...

And now, I also got confused what your common definition of "feather" the valve means??

I am still struggling with abbreviations and "slang" terms....LOL...Old Swedish School you know.....LOL

 

[J_J]

Wow guys, again, eternally grateful for the education..

JJ, look at the photo of the top of my PT where the control arm comes up. The lift arms are welded in the same area, so I am not sure if cutting that area open would be a wise idea. Your thoughts?

Carl,

First, try and determine if your valve has PB. The lift arms on your machine and mine are similar. As far as you have enough space to fit the valve, I would call Baileynet and ask them for dimensions on the valve. That is a six station setup, which should satisfy any future needs.

I have two of these valves that are PB capable, and they are small. might be enough room for both to go in the same spot as the three gang valve, or remove the three section valve, fill in the hole, and bore new holes for the two new valves. Will control four cylinders



https://www.surpluscenter.com/item.asp?UID=3836011719354492&item=9-7401&catname=hydraulic

If you click on DRAWING, it will show the size of the valve.