Question about steel strength??

[jodebg]

Thanks for the clarification. There's no .253 square tubing for the 2x4 forks?

One important question remains. Where is the ideal location for welding the lower link brackets and mounting to top link.
I know you had mentioned before that this will assist in maximizing lift capacity.

So, what is the theory behind where the links should mount and what the links should
look like when connected to this frame, when the frame is sitting on the ground?

5x3x1/2 has an ID of 2x4. If you used 2x4 tube for the forks, they could be inserted and removed same as the plans.

 

[LD1]

I would measure the height of the 3PH arms in the lowest position. Then weld the pins just a tad above that. That will make sure the forks will go all the way to the ground.

Then try to keep the toplink parallel to the lowers. That will keep the forks pretty level when lifting. I'd use the top hole on the tractor side for making that reference. Then you have the option of using a lower hole on the tractor side to have the fork tips pitch up higher when lifting if so desired. Handy for lifting things like logs or something to keep them from rolling off the back. Not as handy for pallets tho

 

[LD1]

All three point hitches that I have seen work on the principal of a Third Class lever

NO

Even if it is a true parallelogram style linkage the farther out from the fulcrum the load is the more effort it takes to lift it.

NO again.

A parallelogram linkage does NOT need more force for a load farther out. It makes no difference where the load is, the force required to lift it is the same.

We have been down this road before.:mur:

 

[jodebg]

LD1-I want to make certain that I fully understand. Not sure what is meant by tractor side?

I currently have a King Kutter carry all attachment on my 3ph. The lower links are slightly pointing down-lower at the ends.
The top link is pointing upwards-higher at the ends.

Correct me if I am wrong. Your placement of the mounting brackets will have both the upper and
lower links parallel-both pointing downwards-and parallel to each other.
This will put the mounting brakets closer to each other, than the plates on the KK?

Then I would add a second upper link hole as described.

I would measure the height of the 3PH arms in the lowest position. Then weld the pins just a tad above that. That will make sure the forks will go all the way to the ground.

Then try to keep the toplink parallel to the lowers. That will keep the forks pretty level when lifting. I'd use the top hole on the tractor side for making that reference. Then you have the option of using a lower hole on the tractor side to have the fork tips pitch up higher when lifting if so desired. Handy for lifting things like logs or something to keep them from rolling off the back. Not as handy for pallets tho

 

[LD1]

LD1-I want to make certain that I fully understand. Not sure what is meant by tractor side?

I currently have a King Kutter carry all attachment on my 3ph. The lower links are slightly pointing down-lower at the ends.
The top link is pointing upwards-higher at the ends.

Correct me if I am wrong. Your placement of the mounting brackets will have both the upper and
lower links parallel-both pointing downwards-and parallel to each other.
This will put the mounting brakets closer to each other, than the plates on the KK?

Then I would add a second upper link hole as described.

Do you have more than one hole for mounting the toplink to the tractor (tractor side)?

And if so, use the TOP hole, and make it parallel to the bottom links. If the bottom arms are pointing downward at 15 degrees when hooked to the forks, give the toplink a 15 degree downard angle and thats where you want it mounted to the forks at.

On your carry-all, with lower arms pointing down and toplink pointing up, you notice how it doesnt stay level when raised? See how the tail end of the carryall pitches up higher than the front? Making the toplink and lower links parallel causes a MUCH more level raise. But use the top hole on the tractor as I mentioned. Cause it still gives you the option to go to a lower hole at the tractor, and will make the forks pitch up like your current carry-all if the application necessitates it.

If you goof up and use the lower hole and make it parallel based off of that, then decide to hook to the top hole, it will have the opposite effect. As you raise the forks, the tips will raise at a slower rate. So on the ground the forks may be level, but when raised they will be tilted down trying to dump whatever load is on there

 

[jodebg]

LD1-When I went out to look at the King Kutter I began to wonder
if this frame design (angle iron) would be better than using steel tubing?

Here is a link to a photo of the KK..
King Kutter Carry All, Model CA | Category 1 Scoops| Northern Tool + Equipment

Would an angle iron frame be as strong as the 2.5x2.5x 1/4" tubing frame?
Might make the integration of the lower receivers easier.

Just noticed that they also make similar pallet mover. Here they use a
frame with tubing?

King Kutter Pallet Mover PM-15 by King Kutter for $339.97 : Rural King

The forks are 4x2x 1/4"

For the $340, powder coated and all, maybe??

 

[LD1]

Tubing is stronger. Especially for the frame where the forks are trying to twist what they are attached to. Tubing has alot better torsional strength than angle.

If you are looking to buy a set of forks rather than make, give agri-supply a look. They seem to have better prices, though I dont know what shipping would cost

Pallet Forks, Pallet Fork, 3 Point Pallet Forks | Agri Supply, 72511, 3 Pt Palle

 

[Sodo]

Agreed tubing is substantially stronger than angle for the same weight.

I kinda like that agri-supply fork, very simple, but not collapsible. It leaves no question where are the load paths.





Thanks Mace thats helpful,,,,, IF it's how the 3-pt works inside a B7800. LD1 you seem to say this is NOT how a tractor 3-pt is actuated? I looked around on the net a little, could not find any useful mechanism diagrams.

If 3-pts are generally actuated as in the (Mercedes Benz / Unimog) pic above the lifting capacity is obviously position-dependent. Just at a glance I can see that there are positions where the lift force will be 50% of its max. LD1 note that the parallelogram linkage can vary this output further (plus & minus) because the top & bottom links are not same length. The output of a parallelogram is not given linear, it depends what you are measuring. For example if the input is a constant torque then output is sinusoidal (extremely non-linear) but some segments of the stroke can approximate linear.

Joe, at this point it would be useful to solicit with a new post: "3-pt Forks, how much can you lift?" could get better info than page 9 of "steel strength". Feet-on-the-ground responses could be more useful than the gearboy speak. The gearboy has to make a lot of assumptions and to follow it or USE it you have to know what these assumptions are (and agree with them too).

It would be interesting to see how much the various tractors can lift. If you get a response from a B-Series fork (or boom) owner who can offer reliable weight measurements (barrels of water or fuel?) then you have something. I would not be surprised if a 3-pt offers a varying lift force. For example, perhaps it can lift twice as much in the first 1/3, as in the last 1/3.

 

[jodebg]

Do you have more than one hole for mounting the toplink to the tractor (tractor side)?

Tractor side...I get it now. Yes, I have 2-upper and lower.

And if so, use the TOP hole, and make it parallel to the bottom links. If the bottom arms are pointing downward at 15 degrees when hooked to the forks, give the toplink a 15 degree downard angle and thats where you want it mounted to the forks at.

Placing the brackets in this configuration may allow me cut down the overall height of the frame, square it off at a lower point, and shed a little weight.

On your carry-all, with lower arms pointing down and toplink pointing up, you notice how it doesnt stay level when raised? See how the tail end of the carryall pitches up higher than the front? Making the toplink and lower links parallel causes a MUCH more level raise. But use the top hole on the tractor as I mentioned. Cause it still gives you the option to go to a lower hole at the tractor, and will make the forks pitch up like your current carry-all if the application necessitates it.

That is correct, it does not stay level. Now I understand about using the lower hole-tractor side.

If you goof up and use the lower hole and make it parallel based off of that, then decide to hook to the top hole, it will have the opposite effect. As you raise the forks, the tips will raise at a slower rate. So on the ground the forks may be level, but when raised they will be tilted down trying to dump whatever load is on there

Got it, thanks.

 

[jodebg]

Still like the idea of adjustable forks, and the freight at AS was $100.

I am planning to locate the outside receiver centered on the FEL arms at 41" OC.

Being that I have not used forks before, what would be a good minimum spacing?
In other words are there times that the forks are used closely spaced and what would
be a good inner receiver spacing?

Any other advice on receiver spacing would be helpful.