Double Pilot Operated Check Valve for 2 Cylinders???

[638]

Guys, after following this thread for a while, And having some little hydraulic training over the years, I would like to make a comment. If I remember correctly, the only way that two hydraulic cylinders can be syncronized is with a flow divider. A flow divider is nothing more than two hydraulic motors with their shafts connected together. Pressure input is split between the two motors with the exhaust from each motor going to each cylinder. Thus, each cylinder gets exactly the same amount of oil and extending exactly the same distance.

ron

 

[Wayne County Hose]

So let me ask you again Wayne.
If two cylinders are set up in parallel like Skunk was wanting,
using the flow controls,
after they are synchronized with no load on them,
they will move the same amount together regardless if you pinch one of the rods shut, so it will not move or would be much harder to move than when it was free (like it was jammed).
Is that what you are saying?

No, that's not the case. Given equal forces on the cylinder (or close to it), yes. Fluid will always flow the path of least resistance. Once you put a load on one, the other will extend until pressures within the cylinders equalize.

Unfortunately for me, my brain works one speed, my typing is infinitely slower. My thoughts run ahead of my typing and things come out jumbled.

 

[3RRL]

Thanks for explaining Wayne, since I was not exactly clear on that.
You have to excuse my ignorance but I am very interested in learning about this. LOL ... I am right there with you about the brain and typing speed man. See my signature.

Hi Ron, thanks for posting about the flow divider and how that works using two hydraulic motors with their shafts connected. Seems like it would work providing equal force to each cylinder regardless of how much force against either one. Is that right? Again, I'm asking...

So when one of the cylinders gets stopped, the other one does too, right? Do the hydraulic motors stop turning and does the excess oil then bypass via a pressure relief in front of them (the motors)? That would keep them synchronized then. Is that right?
Thanks,

 

[Wayne County Hose]

If I remember correctly, the only way that two hydraulic cylinders can be syncronized is with a flow divider. A flow divider is nothing more than two hydraulic motors with their shafts connected together. Pressure input is split between the two motors with the exhaust from each motor going to each cylinder. Thus, each cylinder gets exactly the same amount of oil and extending exactly the same distance.

ron

Wow, I did not know that. I've pondered it a while, and it does make perfect sense. I learned something today. Now I will go to sleep.

 

[638]

3RRL,

Yes, assuming that there is absolutely no internal leakage in the flow divider, if one cylinder is stopped due to load and the other cylinder has no load, it will stop also, but due to normal internal leakage of the flow divider the unloaded cylinder will creep very slowly. As in any other system, the system pressure relief valve will dump excess pressure back to tank. On all of the systems that I was involved with, the cycle time of cylinder extension was so short, that there was never any problem of the cylinders getting out of sync. By using two additional flow dividers on the down side of a flow divider, you can sync. 4 cylinders to operate at the same time with the same force at each cylinder.

ron

 

[6sunset6]

I posted else where but uneven movement is exactly how I straightened out my QA that I bent. I blocked the good side so that cylinder stopped short and the other one keept trying to go further. Worked after I heated up the bent part.

 

[3RRL]

Thanks for great explanation Ron.
I'll bet it's kind of pricey, but it seems like that set up would work flawlessly for Skunk's project.

6sunset6,
I read where you did that. Pretty clever thinking on your part.
I'm gonna date myself, but I remember a TV show ... 77 Sunset strip starring Efrin Zimbalist Jr. as "Stuart Bailey" and Edd Brynes as "Kookie". Does that have anything to do with your user name?