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?
Lift Cylinders
- Thread starter Lucky
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hurleyjd
Well-known member
Lucky said:
What tractor are you using. You may not have the pressure or the flow for the cylinders.
hurleyjd
Well-known member
I would like to add that the cylinder that does not pick up as high might need the internal seals replaced.
Redgully
Well-known member
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.
Lucky
Well-known member
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.
Lucky
Well-known member
https://m.youtube.com/watch?v=91gTeV21Uas
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.
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.
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.
Tractor connected to port A of 1st cylinder, hose from 1B to 2A, then hose from 2B back to tractor.
cfpinz said:
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.
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.
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.
Atimm693 said:
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?
Lucky
Well-known member
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.
Lucky said:
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.
Dsth
Well-known member
Both cylinders are the same size and plumbed in parallel. The roller is full of water but it also has to have some air in it to compensate for expansion at different temperatures; therefore, when the water moves more to one end, the opposite end becomes lighter. The cylinder on the lighter end will lift faster or easier because of less weight. the opposite happens when you let it down. the heavier end will drop first. adding restrictions in the lines will not help your problem just slow down the oil flow. Once one cylinder gets to the end of its travel, the other cylinder will finish its travel whether it is going up or down. Even on perfectly level ground you will have the water shifting from one side to the other and uneven lift. The roller is designed to flex as it is lifted or lowered. The roller should have baffles in it to keep the water from moving too quickly, but the cylinders will react to just a few pounds of weight difference. I do not think their is a solution for what you are looking for, but I will check back for updates. good luck
Redgully
Well-known member
I think what will make it really difficult to change is there is three points of weight bearing, the front being the hitch and that is your balance point. The only real way i can see you fixing it is another set of hoses and a control valve so you can control each hydraulic independently.
Dsth
Well-known member
Redgully's solution will work if you use a separate hydraulic output from your tractor for each cylinder. you would have to manually control each cylinder to try to keep it level.
hurleyjd
Well-known member
With the design of the implement and the placement of the lug on the wheel beams really puts a load on the cylinders. If I was designing it I would used cylinders with a longer stroke and placed the lug on the wheel beam half way from the axle and the pivot pin on the implement.
