SCV operation

[jackd]

I'm adding a sickle bar cutter to my list of "toys", and it has a hydraulic cylinder to raise the bar. I don't have a third SCV, and my dealer says he can run ONE line from the sickle bar, that I can attach to the manifold that operates the FEL. He says I only need one line, because the bar is gravity lowered, as is the bucket on the FEL. My understanding is that the SCV has TWO ports for curling the bucket on the FEL -- one to curl, and the other to allow fluid to return as in essance allow the bucket to drop, via gravity. If I only have one line on the sickle bar, what allows pressure relief and lowering of the sickle bar?
If anyone can make any sense out of what I'm trying to ask, please help! /forums/images/graemlins/crazy.gif

Thanks,

JackD

 

[rockyridgefarm]

Every supply must have a return. You could plug into the two that affect bucket curl. Even though there might not be downward pressure, the oil has to come back out for the cylinder to drop...

 

[jackd]

Thanks Mike...thats's what I thought...

JackD

 

[timb]

What you're talking about is trying to run a single-acting cylinder with a double-acting SCV valve intended to run a double-acting cylinder. I think this can be done - but it sure sounds like it's a problem.

Everything I have access to right now uses double acting cylinders - how DO you run a single-acting cylinder from a double-acting SCV (with or without float) and control it in both extension and compression without putting the system into relief?

 

[jackd]

Tim:

According to the Dealer (ANOTHER conversation), the weight of the sickle bar will transfer the fluid back to the reservoir, through the SCV. He also contends that, since the bucket curl, "pressures" both up & down, it doesn't make any difference which port the sickle bar is connected to. /forums/images/graemlins/confused.gif

Jack

 

[cowboydoc]

Your dealer is exactly right. YOu can easily plug into any one of your scv's on the loader or in the back. You only need one port. My new rake works exactly the same way.

 

[jackd]

Thanks Richard -- it's to be delivered Fri. -- guess I'll find out!!! I feel a little more "comfort" now.

Jack

 

[Bird]

And as with Cowboydoc's rake, the Gehl mower/conditioner I used in cutting hay had a single line to raise it for transport or in turning at the end of rows; gravity lowered it.

 

[JerryT]

I am glad you asked this question. I bought a sicklemower several years ago and hooked the single line to one of my T&T fittings (had to disconnect the other). It works but I am not sure how. When lowering the bar I get a obvious increase in load on the hydraulic pump, but it works. A duel action cylinder would have been prefered, because if you have the bar up at 90 degrees, gravity doesn't help unless you can find a hill.

 

[timb]

That's what I was thinking - while trying to lower a single-acting cylinder, the other side of your double-acting SCV that is trying to 'send' fluid is going to be stalled (as if the cylinder it thinks it's attached to has reached it's travel limit). As long as the overall system doesn't care all that much (for all the longer it takes to drop the single-acting cylinder down to the desired point) then OK. I kind of thought the system relief valve would be singing the whole time though.