Help with 3 point fork design please

[oldboyscout]

I'm about to build a pallet fork frame for my 3 point hitch. I'd like to keep the top link attachment low, so it is parallel to the lift arms, so the forks stay level when I lift.
Does that increase the forces on the 3 point linkage too much?

I'm also planning to simply weld the bottom and top bars to vertical 1/4" x3x3 angle, and run 3/8" x 2" bar at right angles to the top and bottom bars to stiffen them. I think this will be way stronger than anything I can lift with my B2620?

 

[oldboyscout]

I'll cut the bars to 27"-width of the lift arm spacing. I need it for pallets 36" wide.

 

[oldboyscout]

If the top link and lift arms stay parallel, the implement stays level, right?
If the top link is angled up, the more you lift the steeper the implement point up?

 

[beppington]

If the top link and lift arms stay parallel, the implement stays level, right?

Yes, I believe that's right.

If the top link is angled up, the more you lift the steeper the implement point up?

Yes, I believe that's right, too.

 

[LD1]

If the top link and lift arms stay parallel, the implement stays level, right?
If the top link is angled up, the more you lift the steeper the implement point up?

Yes, I believe that's right.



Yes, I believe that's right, too.

YES and NO.

It is true ONLY if the toplink is the same length as the lower arms.

IF it is shorter, it will have a different swing arc(radius) than teh lower arms. And would still tilt the forks when raised.

Thy the link in the third post of this thread that I posted
http://www.tractorbynet.com/forums/build-yourself/214292-3-pt-hitch-calculator-cant.html

It is a 3PH calculator to simulate just what you want. You have to take some measurments off your tractor and plug them in, and then some measurments off of the forks you are going to build.

If you are even attempting to figure this out, I am sure you will make good use of that program:thumbsup:

 

[oldboyscout]

Thanks. I'm not worried that it stay PERFECTLY level, just that it doesn't tip so much that my firewood comes tumbling down.

 

[beppington]

YES and NO.

It is true ONLY if the toplink is the same length as the lower arms.

Well, I started to include in my post that the pivot points (at the tractor ends) of the lift arms & top link would need to be aligned (in the same plane vertically) for the answer to be Yes, but figured they would be close enough for his plan.

 

[oldboyscout]

so is there any issue with forces being to high from keeping the top link so low?
I know you're not supposed to use the lower top link location on the tractor as it reduces lift capacity.

 

[MMagis]

I replied to your other post, but I didn't see this one.
How do you intend to keep your lift arms parallel? They lift by rotating, so you'll never keep them level. If it could be done, all carry-alls would be built that way. There will be a point that you have the top link attachment so low that it will bind when you try to lift, but I can't say exactly where that is.

 

[LD1]

I replied to your other post, but I didn't see this one.
How do you intend to keep your lift arms parallel? They lift by rotating, so you'll never keep them level. If it could be done, all carry-alls would be built that way. There will be a point that you have the top link attachment so low that it will bind when you try to lift, but I can't say exactly where that is.

I dont think he is talking about lowering the TL.

Basically, in a nutshell, for something to raise and remain parallel, the lower arms and the upper toplink must be parallel to eachother, AND the same length. If that is the case, there is going to be NO binding at all.

So, since most tractors TL are running on a bit of a downhill angle toward the front of the tractor, to get them parallel, you can either RAISE where it is mounted on the tractor, OR lower it on the implement side. For example, if the distance between the lower arm pivot @ the rear axle, and the toplink hole you choose, is 10", you simply make the toplink mount on the implement 10" above the lower pins, and thenn adjust the TL so that it is the samelength as the lower arms, or close to it.

And as far as it creating more stress on the 3PH, it is minimal. Where the big change is, is on the implement.