Hydraulic Top Link M9540

[AllDodge]

Well alrighty then

 

[LD1]

Let's look at the facts, which you seem to confuse with opinion.

I'll use my MX for example....with a mounted woods ds96 cutter. Which is an 8' twin and weighs 1620#

The weight is centered on this cutter right about where the gearboxes are. Which is about 30" behind the lower pins.

The toplink pin is exactly 16" vertically above the lower pins.

When the cutter is raised, that weight 30" back is like the long arm on a crowbar...and the 16" is like the short arm.

The amount of force PULLING on the toplink is INCREASED. By a factor of 30/16.

With the 1620# cutter that is about 3040#.

If I had that 2" cylinder you linked with it's 1-3/16 rod...it has 2.04 SQ in of piston on the rod side. This would make the pressure on the rod side 1490psi.

A 2.5" cylinder with 1.5" rod...3.14 SQ inches on rod side....psi would be about 1000

With my 3" cylinder and 1.5" rod and it's 5.29sq inches of area....psi required is a modest 575psi

But these are optimum figures. In the real world the cylinder is mounted on a bit of an angle. Making it require a higher pressure. The exact amount depends on the geometry of your machine and which mounting holes the toplink is in.

In reality.....it takes 750psi to lift my cutter because of the angle. Or about 30% more that what is calculated for a straight line pull on the toplink.

That would mean the 2.5" cylinder would need to sustain 1300psi. And the 2" cylinder would need 1940psi.

And this is just a lowly 1600# 8' cutter.

Based on that, a 2.5" cylinder would limit you to about a 3000# implement and no more than 30" back. Farther back....or heavier and you are outta luck. Forget about running a mounted 10' rotary cutter of any robustness.

Not really quite sure what you are trying to save or trying to prove by going with a smaller cylinder???

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[ovrszd]

For five years I carried a JD M1008 mounted 10ft cutter with my M9540. Without FEL that load required 1300lbs of fromt suitcase weights and still carried the front tires in some situations. I don't know the forces exerted on my 3" TL BUT I'd guess I would have had problems with a smaller cylinder. Can't prove that though. Didn't want to find out.

 

[ptsg]

...

The lifting force of the tractor is determined by measuring the force applied by the 2 lower arms. The top link is has the pivot load, and for the most part is along for the ride. The TL does not pickup the entire load. If all things were equal it might have 1/3 the load or 1833

...

Then, just take a moment to think why 3 pt backhoe usually break the top link mount and the top of the transmission case on tractors...

We also have to consider bouncing of heavy implements in the back of the tractor when going on a rough terrain. That's a lot of force on the top link.

 

[ovrszd]

When a 3pt load raises the front tires of the tractor off the ground where is the most load applied? The two 3pt arms? Or the single top link?

 

[LD1]

Then, just take a moment to think why 3 pt backhoe usually break the top link mount and the top of the transmission case on tractors...

We also have to consider bouncing of heavy implements in the back of the tractor when going on a rough terrain. That's a lot of force on the top link.

Ahhh, someone who seems to understand:thumbsup:

Someone thinking that the Toplink is only carrying 1/3 of the load of the hitch has a serious mis-understanding of how the hitch works.

Also thinking that there is a pressure relief gonna bail you out if you try to lift something too heavy.....also dont understand how that works.

If you induce a load on the toplink by an external force (not its own hydraulic capacity)....by lifting a big implement....there is NO pressure relief for the toplink. Unless you call a blown hose and face full of oil "pressure relief"

Of course this is all just my "opinion" and I dont know what I am talking about

But for a reason I cannot figure out.....someone is trying to save $20 or $30 on a toplink cylinder because they have it set in their head that they are right and want to attempt to prove everyone wrong because they cannot be told otherwise or admit that they are wrong.

Im just trying to help someone from making a mistake. Its clear they dont want my help. But hopefully this will help someone else reading this that wants a toplink

 

[AllDodge]

Your using some facts and again some assumptions.

Its always good to find what you know is true and then fill in the blanks working backwards.
Start with what someone "thinks" the know is, weight 3041, pressure 575 psi and then work backwards

What is pictured
Gauge reading and calculated surface area (575 psi x 5.29 sq in) = 3041 all is good [Note: Gauge being used while not calibrated gave a reference point]

If I had that 2" cylinder you linked with it's 1-3/16 rod...it has 2.04 SQ in of piston on the rod side. This would make the pressure on the rod side 1490psi.

Calculate surface area for (radius Squared x Pi = surface area)
2.5 = 3.14 then use 3041/3.14 = 968
2.0 = 2.04 (listed but inaccurate) 3041/2.04 = 1490 but actual is 1.954 [(2 in = 3.1415)-(1.1875 rod)] which yields 3041/1.954=1556

Just working in reverse does not provide what happens because not all factors have been calculated

The 30/16 factor means nothing. How does the 30 in arms extension compared/calculated to a distance separating the upper link to the lower arms? Both lower and upper extensions are extended, and at different lengths, but where is the calculated loads on each and how the difference in angles apply's to total load.

To prove your point, there would either need to calculate the load variables at given angles, or would need to at least install the other size cylinders and measure the pressure with the same gauge.

 

[LD1]

Your using some facts and again some assumptions.

I made no assumptions.
Other than assuming you bought a 100hp machine with a 5500# (or optional 8000#+) hitch capacity because you didnt want a 50-60hp machine and the associated limitations with it.

Its always good to find what you know is true and then fill in the blanks working backwards.
Start with what someone "thinks" the know is, weight 3041, pressure 575 psi and then work backwards

What is pictured
Gauge reading and calculated surface area (575 psi x 5.29 sq in) = 3041 all is good [Note: Gauge being used while not calibrated gave a reference point]



Calculate surface area for (radius Squared x Pi = surface area)
2.5 = 3.14 then use 3041/3.14 = 968
2.0 = 2.04 (listed but inaccurate) 3041/2.04 = 1490 but actual is 1.954 [(2 in = 3.1415)-(1.1875 rod)] which yields 3041/1.954=1556

Your attempt to point out minor errors or oversights on my part just show the lack of education about the subject matter.

Sure, I am human. Maybe I keyed something in wrong, mistakes happen. But in this case, your attempt to try and "prove" you are smarter failed miserable. You need to re-evaluate the ROD SIDE surface area of a 2" cylinder.....with a 1-3/16" rod diameter

And thinking gauge calibration is even relevant to what I am talking about is laughable.

Just working in reverse does not provide what happens because not all factors have been calculated

The ONLY factor I didnt calculate was the effect of the "angle" of the toplink. Why didnt I calculate it...
1. Its irrelevant because the effects can be seen in the gauge
2. It is variable and adjustable
3. Not worth my time to calculate that if you cannot comprehend other, more basic concepts of how the 3PH works

The 30/16 factor means nothing. How does the 30 in arms extension compared/calculated to a distance separating the upper link to the lower arms? Both lower and upper extensions are extended, and at different lengths, but where is the calculated loads on each and how the difference in angles apply's to total load.

This is the basic concept you fail to understand.
The 30" has nothing to do with the lower arm length. Its is how far BEHIND the lower arms (specifically the ball ends) the load is applied.

You fail to realize that when you lift something....your load (implement) is rotating about the LOWER pins. The ONLY thing keeping the rotation in check is the toplink. The toplink that is in TENSION. The toplink that is mounted (in my case) exactly 16" above the lower pins.

What that means in simple terms is.....a load 16" BEHIND the lower pins....its 1:1 ratio. Every pound you put on @ 16" is PULLING on the toplink by a pound. At 32"....every pound that you put on....is pulling with TWO pounds of force.

Since MY rotary cutter is 1620#....and the center of that weight is ~30" behind the lower pins....that is ~3040# PULLING at the toplink pin where the implement attaches.

Since the Toplink is mounted on an angle (and that angle is adjustable with different mounting positions) the toplink sees MORE than 3040# of force. In my case how the cutter was mounted....about 30% MORE force.

Its about as simple of a lever as you can get . Draw a line like this |____ (kinda like a carry-all platform). with the pivot point being the the corner of the 90 degree angle. Believe it or not....crowbars, nail pullers, hammers, gorilla bars etc all operate of this same leverage principal.

To prove your point, there would either need to calculate the load variables at given angles, or would need to at least install the other size cylinders and measure the pressure with the same gauge.

No need to try all different cylinder sizes. The relationship to cylinder size (in sq inches of piston area) and PSI is linear.

For someone who still seems to think that the toplink only sees 1/3 of the weight on the hitch, and still thinks a 2" cylinder would be enough for your 5500# lift capacity, it is clear you simply do not understand yet. And weather you will ever understand (or admit to understanding) is another matter.

The fact that SEVERAL other members here with similar machines ranging from the 7040, 8540, and 9540 all say they used 3" cylinders. And the fact that one of the most respected toplink guys recommends a 3" cylinder for 60-100hp machines should tell you something right there.

But maybe you never plan on using more than a few thousand pounds of your capacity? Maybe you will only use light attachments like a landscape rake, or bale spear lifting 1000# bales? You will certainly be alright with a 2" or 2-1/2" cylinder if thats your plan. I just dont understand the logic of limiting your rear hitch to something a 50-60hp machine could do just to save a few bucks....when you spent several grand more to get a 100hp machine instead of a 60

 

[3Ts]

The 30" has nothing to do with the lower arm length. Its is how far BEHIND the lower arms (specifically the ball ends) the load is applied.

The proper term here is torque - weight x distance. In this case 1 pound at 30" is 30 inch pounds. Since this is rotating about the lower lift pins, the torque on the upper link is also 30 inch pounds, but the distance is only 16" so the upper link sees a force of 1.875 pounds pulling on it for every pound sitting at 30" behind the lift pins.

Hope this helps to clarify things.

Also, the geometry is important and is continuously variable so assumptions have to be made. The other position, where all the weight is at and in-line with the lift pins produces zero torque (1 pound times 0") and a piece of baling wire would work.
Also #2, impacts from bouncing is really really bad! shock loads are many times static loads.

 

[AllDodge]

impacts from bouncing is really really bad! shock loads are many times static loads.

Do agree and could be a very big factor

Maybe it comes down to a hydraulic top link should only be used on tractors under 60HP. The MX5200 3 pt lift is 2310lb, and things bouncing around can well exceed this limit and then add in that on the TL and the check valve pressure limit could be reached momentarily.

So I'll add my little cylinder and play around with light things, and if I get a heavy attachment someday, I'll change to a screw type.

Got the eye cut off and longer one welded on yesterday