3 Point hitch upper link

[MoArk Willy]

I have a question that I cannot seem to figure out the answer to.
Let me pose the hypothetical.
Let's "assume" you have a 1000# load on your 3 point hitch and you are able to lift it.
The lower arms lift the weight and the top link steadies / adjusts it and keeps it from just flopping over.
How much of that 1000# weight is the top link actually supporting?
Is this something that can be calculated.....is there a formula?
One thing we can be sure of is that the 1000# weight is being lifted by the lower arms....no doubt about it since the top link doesn't do any lifting.
So by balancing the load....there is definitely some weight on the top link.
What percentage of this weight is carried by the top link?
Is it substantial in comparison to the lift arms?...is it minimal?
When you have too much weight on the 3 point and you try to lift it and the front of your tractor goes up in the air.............well....you know what I mean.

 

[LouNY]

The toplink is handling the entire hanging load in tension.

 

[SPYDERLK]

I have a question that I cannot seem to figure out the answer to.
Let me pose the hypothetical.
Let's "assume" you have a 1000# load on your 3 point hitch and you are able to lift it.
The lower arms lift the weight and the top link steadies / adjusts it and keeps it from just flopping over.
How much of that 1000# weight is the top link actually supporting?
Is this something that can be calculated.....is there a formula?
One thing we can be sure of is that the 1000# weight is being lifted by the lower arms....no doubt about it since the top link doesn't do any lifting.
So by balancing the load....there is definitely some weight on the top link.
What percentage of this weight is carried by the top link?
Is it substantial in comparison to the lift arms?...is it minimal?
When you have too much weight on the 3 point and you try to lift it and the front of your tractor goes up in the air.............well....you know what I mean.

The lift arms support all the weight. The top link tension and active angle relation during lift causes the implement to rise almost straight up rather than rotating with the lift arms. This amounts to an imperfect parallelogram lift system allowing a long implement close to the limit of lift arm force at the balls to be lifted.

 

[CalG]

If you were to make a sketch, the answer would reveal it's self.

Imagine a 1000# of barbell weights on a straight round bar between the lift arms.

NO TOP LINK IS NEEDED to control the load.

Now, sketch out a boom pole extending 10 feet off the tractor lift arms with the same stack of weights hanging from a chain at the boom end.

Resolving loads via simple "triangles" would reveal the tension on the top link.
(I'm not going there, but it is Mechanical Engineering 101!)

 

[oosik]

Can't be solved with any biological formula. I'm lost.

 

[CalG]

Can't be solved with any biological formula. I'm lost.

Has to be either oxidation or reduction,

eventually

 

[Smokeydog]

Depends on the geometry of the load.
Lifting the top link is in tension. Just like in rigging the tension in lifting rigging depends on the angle. Can exceed load weight. Plowing or grading in compression. Dynamic loading, in motion or influenced by outside source, can exceed static load many many times.

If there were load gauges on our 3pt or FEL components most folks would be shocked by forces they are subjected to.

 

[CalG]

Depends on the geometry of the load.
Lifting the top link is in tension. Just like in rigging the tension in lifting rigging depends on the angle. Can exceed load weight. Plowing or grading in compression. Dynamic loading, in motion or influenced by outside source, can exceed static load many many times.

If there were load gauges on our 3pt or FEL components most folks would be shocked by forces they are subjected to.

The 3X3 X 1/4 inch angle iron that is the top link fixing point on the Fordson is bent, bowed out from tension of the top link/

It was from "hobby horsing" the tractor with a rather large pull behind snow blower.

Just a look at the bend sobered me right up! And it's not all that much, but I have a feeling for what it takes to do that!

 

[TerryR]

It's not too hard to get an estimate if you make a few simplifying assumptions:

If the weight of the implement is 1,000 lb. the tension in the top link is 2,000 lb., assuming:

1. The center of gravity of the implement is 4 ft. behind the 3-point pins. Probably reasonable for a box blade or flail mower. If it is longer, the tension in the top link is greater.

2. The height of the riser for the top link is 2 ft. That may be a bit high. If so the top link tension would be grater.

3. The top link and lower links are parallel. They probably are not, which would increase the tension in the top link.

4. The implement is raised until the lower and upper links are horizontal. When they are not the tension in the top link increases.

 

[ptsg]

Get one of those cheap scales, a couple links of chain and replace the top link with it. That way, you'll get exactly what weight is pulling on the top link.

Something like this:

If you have an hydraulic top link, you can also put a pressure gauge with a Tee on the port of the rod side of the cylinder, assuming you know the diameter of the bore, you can calculate the weight as well.