Lift Cylinders

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Lucky
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Lift Cylinders

Post by Lucky » Sat Jun 27, 2020 6:26 am

I’ve got a roller that weighs around 11k when filled with water. It has 2 sets of axles on the back of which each has 2 tires, and each has it’s own hydraulic lift cylinder that are plumbed together. When empty it lifts pretty straight but when full it lifts Really uneven. Wondering if anyones knows of an easy way to get the two cylinders to lift evenly and in sync?



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Re: Lift Cylinders

Post by Atimm693 » Sat Jun 27, 2020 7:44 am

An inline restrictor will help.

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Re: Lift Cylinders

Post by Lucky » Sat Jun 27, 2020 7:45 pm

Adjustable flow restriction or an orifice.

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Re: Lift Cylinders

Post by hurleyjd » Sun Jun 28, 2020 11:39 am

Lucky wrote:
Sat Jun 27, 2020 6:26 am
I’ve got a roller that weighs around 11k when filled with water. It has 2 sets of axles on the back of which each has 2 tires, and each has it’s own hydraulic lift cylinder that are plumbed together. When empty it lifts pretty straight but when full it lifts Really uneven. Wondering if anyones knows of an easy way to get the two cylinders to lift evenly and in sync?
What tractor are you using. You may not have the pressure or the flow for the cylinders.

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Re: Lift Cylinders

Post by hurleyjd » Sun Jun 28, 2020 1:33 pm

I would like to add that the cylinder that does not pick up as high might need the internal seals replaced.

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Re: Lift Cylinders

Post by Redgully » Mon Jun 29, 2020 2:46 am

Could it be possible you have an internal collapse in a hose. This has happened to me before and took a bit of head scratching to work out.

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Re: Lift Cylinders

Post by Lucky » Mon Jun 29, 2020 4:51 am

I’m using a 100 hp tractor. I don’t think it’s a cylinder issue because I can leave the wheels down with the weight of the roller on them for several weeks and no leak down. The hoses appear to be new. I’m going to try and attach a video of what I’ve got. I’m thinking maybe the landing gear needs to be tied together with a piece of square tubing.

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Re: Lift Cylinders

Post by Lucky » Mon Jun 29, 2020 4:59 am



I found this video online. Mine is just like this one. You can see how it doesn’t lift or drop evenly. Might just have to deal with it. It’s not really a big deal but would be better if it lifted evenly.

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Re: Lift Cylinders

Post by cfpinz » Mon Jun 29, 2020 6:13 am

You could set them up so the cylinders are inline instead of parallel, assuming they're both 2 way cylinders.

Tractor connected to port A of 1st cylinder, hose from 1B to 2A, then hose from 2B back to tractor.
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Re: Lift Cylinders

Post by Lucky » Mon Jun 29, 2020 10:07 am

cfpinz wrote:
Mon Jun 29, 2020 6:13 am
You could set them up so the cylinders are inline instead of parallel, assuming they're both 2 way cylinders.

Tractor connected to port A of 1st cylinder, hose from 1B to 2A, then hose from 2B back to tractor.
I’m going to give that a try.

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Re: Lift Cylinders

Post by Atimm693 » Mon Jun 29, 2020 12:46 pm

cfpinz wrote:
Mon Jun 29, 2020 6:13 am
You could set them up so the cylinders are inline instead of parallel, assuming they're both 2 way cylinders.

Tractor connected to port A of 1st cylinder, hose from 1B to 2A, then hose from 2B back to tractor.
Seems to me that would make it worse, in parallel both cylinders are getting equal pressure from the tractor, in series one is getting less because of frictional loss and the difference in piston diameters because of the rod.

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Re: Lift Cylinders

Post by dvcochran » Mon Jun 29, 2020 7:31 pm

Yes, plumbing the cylinders in series (inline) will make it worse.
To the op, may I ask why does it matter in the short amount of stroke?
Regardless, it does not take much to cause this in hydraulics. If the hoses are slightly different in length or if there is air in one circuit (cylinder/hose). Assuming both cylinders are working the same and there are no hose issues a common solution is to add an inline flow control at the raise port of the faster cylinder. Make sure it is turned the correct way so that the fluid free flows the other direction.
Viscosity based on ambient temperature will have some affect so what works in the summer or when the fluid is hot may not be exactly the same when it is below freezing.
If you really need it to be exact, look at the circuits on newer V-rakes. Not nearly as cheap as a flow control but fluid balancers do a good job.

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Re: Lift Cylinders

Post by cfpinz » Tue Jun 30, 2020 6:29 am

Atimm693 wrote:
Mon Jun 29, 2020 12:46 pm
cfpinz wrote:
Mon Jun 29, 2020 6:13 am
You could set them up so the cylinders are inline instead of parallel, assuming they're both 2 way cylinders.

Tractor connected to port A of 1st cylinder, hose from 1B to 2A, then hose from 2B back to tractor.
Seems to me that would make it worse, in parallel both cylinders are getting equal pressure from the tractor, in series one is getting less because of frictional loss and the difference in piston diameters because of the rod.
That's a good point on displacement re: rod diameter. My reasoning was without some type of flow control measures, parallel cylinders allow the oil to flow to the path of least resistance first (think wings on a batwing mower), whereas series would allow for positive displacement of the fluid beyond the first piston. At least one of my discbines has series cylinders for the header lift, but I hadn't paid attention to the bore size of the cylinders. Good point.

I'm not overly familiar with hydraulics, but just bought a NH DuraVee rake last week and the manual references a flow control valve for the wings. Is there such a device that will ensure equal flow to two cylinders?
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Re: Lift Cylinders

Post by Lucky » Tue Jun 30, 2020 11:23 am

This is all interesting. Before I posted I had briefly looked into running the cylinders in series. All the deals I read wanted to know cylinder bore sizes, I guess the fluid capacity was the reason. I’m fairly good at working on hydraulics but know nothing about design.

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Re: Lift Cylinders

Post by Atimm693 » Tue Jun 30, 2020 11:43 am

Lucky wrote:
Tue Jun 30, 2020 11:23 am
This is all interesting. Before I posted I had briefly looked into running the cylinders in series. All the deals I read wanted to know cylinder bore sizes, I guess the fluid capacity was the reason. I’m fairly good at working on hydraulics but know nothing about design.
I suspect in your case there is something just a little different in the way the cylinders are plumbed, one hose just a little longer, one cylinder that leaks a little more than the other, etc. When empty it's not a big deal, but when full of water it is just enough to upset the roller and let the water move to one side.

Ideally you'd want two equal length hoses to the back of the roller, to T fittings, and then equal length hoses to each cylinder.

The restrictor fittings work by restricting the flow enough to force excess fluid through the relief valve in the tractor, creating constant equal pressure in the whole system. Without it, on some tractors the hoses and fittings can flow more than the pump can produce, and max pressure is not reached until one or both cylinders hits bottom.

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