single action cylinder question(s)

[blenderbender]

I picked up a Chinese sickle bar mower that has a single action hydraulic cylinder, power up/gravity down. My Kubota tractor has a single set of rear remotes on a dual action control. I don't understand hydraulics nearly well enough, but I'm guessing this is a problem in terms of using this single action cylinder and I don't have a clue what my options might be other than swapping out for a dual acting cylinder. Any thoughts appreciated!

 

[oldnslo]

Does your tractor have “float” option on the rear remotes? If yes you can use that feature or if not just plug the one hose into one of the quick disconnects. Pull back to raise, push forward to lower same as double acting. Yes lowering you will be at system relief for a few seconds but once you release the lever it will be ok.

 

[ptsg]

When lowering, being a dual acting valve, it will push fluid through the relief at max pressure on the non used port, which is usually bad if done for long periods of time. For a short run like this? It's perfectly fine.

 

[blenderbender]

I guess I can't say if it has a float option on the rear remotes. All I've ever used it for is to adjust the angle on back blade when plowing snow. The lever floats in the center position but I don't think that's what you mean.

 

[blenderbender]

When lowering, being a dual acting valve, it will push fluid through the relief at max pressure on the non used port, which is usually bad if done for long periods of time. For a short run like this? It's perfectly fine.

I'm not certain what you mean by "short run". Thanks!

 

[ptsg]

I'm not certain what you mean by "short run". Thanks!

I meant for a short time. Like lowering the sickle bar. Only a couple seconds, then the valve is back to neutral.

 

[blenderbender]

So, I'm guessing it doesn't matter which port I plug into, but that will determine if I push or pull the lever to lift the sickle bar?

 

[ptsg]

So, I'm guessing it doesn't matter which port I plug into, but that will determine if I push or pull the lever to lift the sickle bar?

Yes. That's it.

 

[CobyRupert]

So, I'm guessing it doesn't matter which port I plug into, but that will determine if I push or pull the lever to lift the sickle bar?

Yes. Basically. When the lever is at neutral position, in the middle, the cylinder isn’t moving, in or out.

To find out if you have a “float position” on the SCV, press the lever all the ways forward (or backwards) and see if it can “pop” forward just a little more to a detent position and stay there. This is another type of “neutral position”, where the cylinder can float in or out, without resistance, if the sickle bar is manually raised or lowered (or is following the contours of the ground) (i.e. “float”).

Gravity will lower the sickle bar to its lowered position when the lever is in float position. Knowing this, you should connect the hydraulic hose to the specific port such that moving the lever lowers the bar just before the lever hits the detent float position. Follow?

You don’t want to press the lever and have it raise raise the bar, then move lever more to the float detent position and the bar drops from some height.

Realistically, it’s not a big difference, but pushing the lever in one direction, shouldn’t have two outcomes (raise and then drop/float).

 

[dicktill]

Does your tractor have “float” option on the rear remotes? If yes you can use that feature or if not just plug the one hose into one of the quick disconnects. Pull back to raise, push forward to lower same as double acting. Yes lowering you will be at system relief for a few seconds but once you release the lever it will be ok.

When lowering, being a dual acting valve, it will push fluid through the relief at max pressure on the non used port, which is usually bad if done for long periods of time. For a short run like this? It's perfectly fine.

Interesting! Can this limitation be "corrected" by running an extra line from the "non-used port (coupler)" back to the tank?

TIA, Dick