Another dumb hydraulic question

Fritz Maurer · Mar 3, 2013

Why are the boom cylinders on farm loaders, of all makes, upside down? On loaders that are actually expected lift something, such as a Ford 4500, the cylinders are right side up. There must be a sane reason they run all that extra hose and tubing down the boom to get to the barrel end of the cylinder, everybody does it. These are mostly quick-attachable loaders, but I don't see what that has to do with it. All 3 pieces stay together (boom, cylinders, and loader frame) it would be just as easy for the plumbing to take a shortcut down the loader frame as it would to run all that stuff across the boom hinge. Thanks, Fritz

John B. · Mar 3, 2013

One reason I can think of.

They can run two lines down the arm of the loader and and "T" it off up high for both cylinders rather than running the hoses under the tractor where they could get caught on something if the base of the cylinders were at the bottom rather than at the top.

Tx Jim · Mar 3, 2013

The barrel end of cylinders holds more sq inches of hyd oil(no cyl rod taking up space) therefore gives cylinder a little more lift capacity for it's diameter. There's also one less set of seals to leak on the barrel end.

Anonymous-0 · Mar 3, 2013

Because the cylinder can lift more by pushing on the non ram side, more surface area, more force. chris

Aaron SEIA · Mar 3, 2013

The barrel end of the cylinder is doing the lifting no matter which way around the cylinder is. Not sure which way you think they should go, but I'm sure an engineer somewhere has a good reason for doing it the way they did.
AaronSEIA

ericlb · Mar 3, 2013

there like that on my loader tractor too, one thing ive noticed is when loading, [ bucket level and on the ground] the cylinders when mounted this way are at their shortest, other than dumping, this may make them less prone to bend the rams when pushing into a pile than if mounted the other way and having the cylinders fully extended when pushing

rrlund · Mar 3, 2013

All? Mine are right side up on my Freeman and White. Upside down on my Dunham.

Anonymous-0 · Mar 3, 2013

I've seen them both ways. I think it is just to keep the seals cleaner, no matter how you turn the cyclinder it is still pushing the load.

JMOR · Mar 3, 2013

(quoted from post at 11:13:27 03/03/13) I've seen them both ways. I think it is just to keep the seals cleaner, no matter how you turn the cyclinder it is still pushing the load.

ellow loader on green tractor with hose hanging down below probably is a large part of the reason NOT to install the cylinders that way. Hose protection is a BIG deal!

rrlund · Mar 3, 2013

The baler twine holding it up there rotted off in the manure. lol

smallercrawler · Mar 3, 2013

Not sure about this, but had an experienced hydraulic design engineer tell me it reduced chances of cylinder rod bending/buckling. Agree with Aaron that cylinder orientation makes no difference as long as "lift" side of fluid flow is applied to the "non-rod" side of the piston. It will have the greater area, therefore the greater force. Only drawback is that the hoses "travel" more during use. Good question!

JD Seller · Mar 3, 2013

I was always told it was for two reasons. 1) Hose routing. The hoses are more protected by running them up the loader rather than under the tractor.
2) So the seals would clean off the ram easier than the stuff staying packed to the seal.

rrlund · Mar 3, 2013

I think it's Westendorf isn't it? That has one now with no hoses at all. Just some kind of pivot fitting. Everything's sealed in the frame.

smallercrawler · Mar 3, 2013

Believe as long as the boom cylinder pivot point is located UNDER the boom pivot point the cylinder will always be retracted at boom down position regardless of cylinder orientation, thus making it more "rigid".

John B. · Mar 3, 2013

Yes it doesn't matter which way the cylinders are mounted. They have to extend to raise the loader so you'll have the same lifting force either way the cylinders are mounted.

Tx Jim · Mar 3, 2013

(quoted from post at 12:42:56 03/03/13) Yes it doesn't matter which way the cylinders are mounted. They have to extend to raise the loader so you'll have the same lifting force either way the cylinders are mounted.

If what you state is true then why will a 3.5 in cyl lift more than a 3 in all other things equal?

Fritz Maurer · Mar 3, 2013

Here's one with the cylinder upside down AND the hoses on the bottom

Aaron SEIA · Mar 3, 2013

Because a 3 1/2" cylinder has more area. A 3" cylinder has an area of 7.07". At 2000 psi, that's 14,154 lbs of push. A 3.5" cyl has an area of 9.6" and at 2000 psi has 19265 lbs of push. The same SIZE cylinder will push the same mounted rod up or rod down. In my simple mind, they have the same chance of bending the rod as the length extended is the same rod up or rod down.
AaronSEIA

JOHNNYfromMI · Mar 3, 2013

Don't know why some are mounted upside down. But a cylinder will always push more than it will pull. It's based on square inches of oil surface doing the work. On the pull action you need to subtract the diameter of the stem on the pull back. I'm sure some will tell me I'm wrong but there is some math that will show that this is true.

greygoat · Mar 3, 2013

The piston end will have power on the full area
of the piston.When pressureizing the rod end,think
of a donut. Because of the area of the piston rod
being "The Donut hole", you are pressurizing the
"Outside of the donut". Less area to pressureize,
thus less force deveoped.

JDB · Mar 3, 2013

More surface area on the piston.
PSI x surface area

samn40 · Mar 3, 2013

On a quick attach loader, if the cylinders were mounted on the tractor frame the hoses would have to run around the nose frame to get between the two cylinders, this would mean they would need a lot of protecting a/ to stop them getting nipped if they were in front of the frame when loading into a high sided trailer or b/ if they were inside the frame,they could be nipped when fitting the loader. It is just as short to take then up the boom of the loader and across to the other ram. plus you can see the hoses when loading. So, to use less hose it makes sense to turn the rams upside down.
Sam

John B. · Mar 3, 2013

I think you misunderstood what I said in my post.
The cylinders on his loader have to extend to raise the loader, regardless which way they are mounted on the machine. So they are using the largest area of the piston inside the cylinder.

John B. · Mar 3, 2013

This is pretty much what I said too earlier.

John B. · Mar 3, 2013

That's true but that is only true when the cylinder is being retracted to lower the loader not when extending the cylinders to raise the loader.

John B. · Mar 3, 2013

One thing I just thought of is that the control valves are usually mounted up high so why not run the hoses from the valve right down the loader arm to the upside down cylinder.

I honestly think neither way is shorter for the hoses by going underneath or around the loader arms. There may be a slight difference but not sure how much. I would run them on the loader to keep them away from the ground and getting hit.

Tx Jim · Mar 3, 2013

I agree with greygoat & JDB. That was the point I was trying to make.

Another dumb hydraulic question

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