Single Action Cylinder Problems

[txnolan]

I reworked an older bat-wing shredder, so that my Dad wouldn't have to crank the wings up every time that he went thru a gate. I added two cylinders that raise the wings by retracting the extended cylinders. The cylinders are connected via a t connection to one line connected to the hydraulics on the tractor. The lift (retract) works great. My problem is getting the single action (double action cylinders with breathers) to extend so that gravity releases the wings. The cylinders don't extend reliably, sometimes I can work the mechanism several times and eventually get the cylinders to extend, sometimes I turn off the tractor. I have occasionally had to disconnect the hose to the cylinder. Any ideas? Please I don't know much about hydraulics, and plan to try separate lines for the cylinders if no better answers are forthcoming.

 

[Tx Jim]

Welcome to TBN
Hello neighbor because Johnson Co Tx isn't that large. I've seen compression springs installed in hinge area to get wings jump started to fold down. Does towing tractor have a float position on hyd control valve?

 

[txnolan]

Thanks, neighbor. I have tried standing, pulling on the wings, not sure how the spring would work. Yes, the tractor does have float. The fluid won't go to the cylinders reliably to make them extend, is it a plumbing issue?

 

[Tx Jim]

Have you lubed hinge pins? Have you considered hooking both wing cylinders together as double acting cylinders? I presume wings won't go down when placing hyd control in float.

 

[LD1]

Thanks, neighbor. I have tried standing, pulling on the wings, not sure how the spring would work. Yes, the tractor does have float. The fluid won't go to the cylinders reliably to make them extend, is it a plumbing issue?

Any pics of how its plumbed?

Are they truly SA cylinders or just DA cylinders with a breather in one port.

To raise the wings by retracting the cylinders is telling me your hydraulic lines goes to the Rod side ports. And you have a breather installed in the Base end port???? Is this correct?

Its highly confusing when in the first post, you say this.

I added two cylinders that raise the wings by retracting the extended cylinders.

Then say this

The fluid won't go to the cylinders reliably to make them extend, is it a plumbing issue?

If it is a SA cylinder, NO fluid should be going "to" the cylinder to lower them. Rather oil should be exiting the cylinder and returning to the tractor to let them bleed down.

 

[txnolan]

No pics of how it is plumbed. Raining, muddy and the mower is at my Dad's. Each cylinder has one line, each cylinder also has one breather. The lines are connected via a t connection to a single line attached to the tractor. The breathers are on the correct side of each cylinder. I asked the hydraulic guy who made the lines for me, and I double checked his knowledge by looking at other single action cylinders that I have on a field cultivator and a wheel rake. I know little about cylinders and probably misspoke about fluid going to the cylinder to make it extend. I just thought it had to, as I assumed fluid left the cylinder to make it retract. I can buy more lines and make the cylinders double action. I might also try to cap one side and see if the remaining side works properly without the other. I just don't understand, if the cylinders retract properly then the fluid is leaving the cylinder, so for the cylinder to extend, where does the fluid go?

Thank you all for your help. I appreciate your knowledge and regret that I don't understand, it just seems so easy. As I stated my wheel rake and field cultivator always work great on one single action cylinder lowering both sides of those implements. Why wouldn't two cylinders work together to lower each side of a different implement?

 

[txnolan]

Lube is OK . May have to convert back to double action as you suggest, but would like to avoid the cost of the hose. Thanks.

 

[Tx Jim]

I just don't understand, if the cylinders retract properly then the fluid is leaving the cylinder, so for the cylinder to extend, where does the fluid go?

When cylinder retracts to raise wings oil is pumped into rod end of cylinder. When hyd control valve is pushed to lower wings oil should leave rod end of cylinder and air enter butt end via breather

 

[LD1]

Weather fluid leaves or enters the cylinder, and weather that makes the cylinder extend or retract, is all dependent on How its plumbed.

Assuming you actually have double acting cylinders....let's if the hose is connected to the base of the cylinder.....fluid entering will extend it. Fluid leaving will retract it.

If the hose is on the rod end, fluid entering will retract it. Fluid leaving will extend it. Just the opposite as if it were plumbed to the base end.

If I am envisioning the design correctly, to lift the wing you need to retract the cylinder. Thus you need power this direction. And the hose should go to the rod end. Under pressure retracts the cylinder and lifts the wing. With the valve in neutral, gravity "should" lower the wing. And as it does it expelled out the fluid back through the valve and to the tractor.

The issue may be when the wing is up, there is not enough gravity pulling down on the wing to overcome the resistance of the fluid and cylinder. Just the geometry of it. And why I requested some pics.

And DO NOT plug the port thats vented. The air has to go somewhere. Best case scenario....the cylinder will just fail to work properly. Worst case, blow out seals or the blue you install. Just don't do it

 

[bigdeano]

I'm thinking if you replace the vents in the base of the cylinders with plugs when the cylinders are extended, the air will compress when they're retracted, and will help to extend the cylinders and lower the wings. The plugs will have to be air tight. Don't see how it could hurt anything. The pressure could be no higher than the hydraulic pressure.