MF20 Industrial, power steering cylinder

hershwork · Apr 1, 2020

I have a 1971 MF 20. I took the power steering lines off of one of the steering cylinders and didn't pay attention to which one went in which hole. I've looked at the parts manual on the AGCO website, but can't tell on there because it shows you the front of the cylinder. I was thinking about it and am pretty sure it doesn't matter. Is that right? That the lines on one side are interchangeable (as long as it's only one pressure and one return on the same cylinder)?

Jim.ME · Apr 1, 2020

(quoted from post at 10:48:05 04/01/20) I have a 1971 MF 20. I took the power steering lines off of one of the steering cylinders and didn't pay attention to which one went in which hole. I've looked at the parts manual on the AGCO website, but can't tell on there because it shows you the front of the cylinder. I was thinking about it and am pretty sure it doesn't matter. Is that right? That the lines on one side are interchangeable (as long as it's only one pressure and one return on the same cylinder)?

No, it does matter, the lines must go to the correct port. When you turn, the piston end of one cylinder and the rod end of the other cylinder get pressurized oil. Turning the opposite direction reverses the pressurized oil to the cylinder ends. If you hook it up wrong the cylinders will "fight" each other. If it does that; try reversing the lines.

hershwork · Apr 1, 2020

Ok, that's what I thought at first, but because mine has 2 cylinders, don't they only "push?" I mean, a hydraulic cylinder doesn't pull, right? I figured one cylinder would be having oil pushed in and the other wouldn't. So, in the cylinder that is not pressurized, oil would just be draining out, but the pressure line of that side wouldn't be building pressure, as long as it's connected correctly to the steering wheel...

Anyway, not arguing, for sure. If it matters, how do I tell? Would it mirror the position on the other side? Or be opposite?

I'm working on the tractor's left side from the driver's seat. I have two lines--one with a 45 at the cylinder, the other with a 90 at the cylinder.

Jim.ME · Apr 1, 2020

Double acting cylinders can push and pull. The piston end of one cylinder and the rod end of the other cylinder get pressurized oil at the same time. The drawing from the parts book may help you understand, unfortunately it does not clearly show which port on the cylinders the hoses hook to. You should be able to follow a line back to the tee, then to the cylinder you did not unhook. The lines you unhooked should be opposite the ones still connected. As I posted rod end of one gets the same oil as the piston end of the other; I would call that opposite the other.

DavidP, South Wales · Apr 1, 2020

Hi, hope you have been able to sort it out from Jim's answer. Just in case you have not:-
Double acting cylinders have a large and small chamber. The small chamber is that on the rod side as part of the volume
is taken up by the rod itself. The large chamber is at the back end and has nothing but oil in it. For the double
cylinder system to work one cylinder has to push and one has to pull at the same time. The oil flow from the pump is
divided and equalized by the large chamber on one cylinder and the small chamber on the other. It's not quite so easy
to determine which hose is connected to the large or small chamber. If you disconnect one hose and turn the steering
(engine off) you will see either a spurt of oil relevant to the direction that the cylinder piston moves or nothing if
you are in effect drawing oil into the cylinder.
Hope this makes sense.
DavidP, South Wales

hershwork · Apr 2, 2020

OK, so that makes sense about the way to connect mattering. How do I tell other than trial and error? I ask because I'm doing a number of things and don't have the battery and steering wheel on at the moment...would need to put stuff back together before I can try it out with the engine running...

hershwork · Apr 2, 2020

Excellent! when I saw David's post and re-read what you said earlier, I did exactly that. Hopefully the holes are not reversed, since they point in different directions...Meaning that you do the opposite of the opposite...doh...

hershwork · Apr 4, 2020

Final update on this issue. I did as Jim suggested and traced the lines hooking to the "opposite" opening from the other side. That was correct. i.e., the top hole on one cylinder does the same thing as the top hole on the other cylinder, either push or pull. Therefore the line from one T coming from the steering column will go to the top hole on one cylinder and the bottom hole on the other cylinder, and vice versa.

Thanks for your help.

MF20 Industrial, power steering cylinder

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