Fork attachment build.

[LD1]

I think you would have been fine with the box tube forks. But then again, we dont know "how much bigger" the tractor is you are building for.

MY forks are 2x4x1/4 and clamp on style.

I cant remember, I think they are somewhere between 36 and 42". I dont think they are a full 42" but I think longer than 36.

Have had them maxed out on my tractor, moving nearly 1000# or more. Some old concrete slabs that I just couldnt lift but could curl and push dragging just the heal of the bucket.

Some of them were just too big to even think about. Put the forks on the backhoe and moved them. The BH bucket flexed pretty good cause of the clamp on style, but the forks were solid and no flex.

Have also moved a heavy steel rack still loaded with steel with the BH and forks. As well as used them with a 10k 12' long forklift boom to set my 40' trusses.

So gut feeling is the forks would be fine on a tractor quite a bit larger than mine. But I am sure I could bend them if I wanted to suspend a load on just a single tip and use them on the BH with 5k+ lift capacity.

What is the length of the forks you are making. I may play with some numbers for a cantilever style beam/load which is basically what they are. How are you planning on doing the flat bar inside them?

FWIW, I think the 4k clamp on forks that are sold everywhere on the net are 2x4x1/4 tube

 

[LD1]

Here is some info:

Assuming 42" forks, ASTM500 steel with 50ksi yeild strength.

Ultimate failure point of 1833# on a single fork tip. (reality would be less since that is a static number and dont account for having a load out there bouncing).

That failure would occur at 0.979" of deflection at the tip

A evenly distributed load, failure would be at 3666# and a deflection of 0.735" at the tip. Thats a single fork.

The longer or shorter the forks are obviously changes things. But also to keep in mind, lifting with an 1800# force on the tip of a 42" fork takes no slouch of a tractor.

 

[Shield Arc]

What is the length of the forks you are making. I may play with some numbers for a cantilever style beam/load which is basically what they are. How are you planning on doing the flat bar inside them?

The vertical section of the forks is 15" long. The horizontal section is 43" long.

I plan on inserting the flat bar in the center of the tube. And make several plug welds to hold it in place.

Worked on bending the FEL mounts this morning.

 

[LD1]

Not going to gain much at all strength wise doing that. The weak link is going to be the heel, not the long section of the tube.

Some 4" long sections of 3x3 angle on the outside corner and inside corner of the heel will do more good than anything.

 

[Shield Arc]

When I built my set. I made an open root weld with 6010. Then capped it with 7018. On the inside of the heel I made a 3-pass fillet weld with 7018. To beef that area up.

 

[Big Barn]

The weak link is going to be the heel, not the long section of the tube. Some 4" long sections of 3x3 angle on the outside corner and inside corner of the heel will do more good than anything.

The heels of my 48" long forks are still square after 15 years. 5000# loads (across 4 forks). Same construction as SA's. And no where near quality of welding as his.




Terry

 

[Shield Arc]

And no where near quality of welding as his.
Terry

Thank you very much! But you realize I've only been welding a few weeks now.

 

[Big Barn]

Thank you very much! But you realize I've only been welding a few weeks now.

Y' know, good thing you don't do YouTube vids like Lanse and Jody. All the newbs would get discouraged awful quick seeing your work and knowing you'd been only welding 'a couple' of weeks.

Terry

 

[LD1]

provided the weld is as strong as the parent metal, each fork is good for 3600# evenly distributed. So a pair is good for a 7200# pallet. Good for most tractors. Just saying the first thing that will fail is the heel.

The entire length of the fork is the same material and cross section. The heel takes the greatest stress. Adding anything inside the tube doesnt do anything for this area. The fork isnt the weak link, the heel is. since its a welded connection, failure isnt likely gonna be a bend, rather a complete failure ripping apart.

The forks "as is" tested to destruction (which will take quite a bit), the heel is the failure point.

 

[dntfxr]

If I can't find any old forks to use locally I may just cheat and put some really small gussets in the joint.

 

[Shield Arc]

you probably only need to extend the flat bar a foot or less from the joint.

That's what I was thinking too.
I don't have a bender that would bend that flat bar with out heat.

 

[Big Barn]

Keep in mind even small gussets will tear up pallets. If that isn't a concern, well then the point is moot.

Terry

 

[dntfxr]

Hahahaa you caught me before I edited my post! I went back and looked at your pics and realized I was thinking of the flat bar being larger and oriented differently. So I deleted my dumb idea lol. But yeah it would take a serious press to make that bend. Your way is much more efficient though!

 

[dntfxr]

Keep in mind even small gussets will tear up pallets. If that isn't a concern, well then the point is moot.

Terry

Yeah probably why no one uses them lol! Mine would probably be termed brush forks I guess... SA's way is much better!

 

[Shield Arc]

Hahahaa you caught me

The more I think about this, I might add two pieces of flat bar to each fork.

 

[dntfxr]

Another way to get it without the bend is just cut some L shapes from plate and stack them together, then put them inside.

 

[4570Man]

Real forklift forks are amazingly strong. The forklift pictured below is rated to lift 7,500 pounds. My Grandpa has a larger forklift rated to lift double that. Using the larger forklift I lifted the back of a Lull weighing 24,000 pounds on the tip of a 48" fork. Ok, I admit the forklift wheelied first, but once I moved the load farther back it lifted the Lull without breaking a sweat. The problem is the forks and mount of that forklift would seriously compromise the lift capacity of a small tractor.

 

[Shield Arc]

If I remember correctly, I think most fork lift load rating is 24" out from the vertical section.
Years ago I got stuck repairing a broken fork for a CAT 966 loader. It broke right in the heel, 8" wide X 4" thick. Used 5/32", 11018 rod, because the fork was made out of T-1 steel.

 

[LD1]

I still dont see how inserting anything in there is going to help, unless you do like someone mentioned and make L shaped pieces and bridge the connection point. Or even cut two L shaped pieces and weld to the outsides. With only 43" forks, there isnt going to be much bending at all up until failure point that will occur at the heel. Adding a piece inside wont do anything to strengthen the heel, thus would still fail with the same amount of weight, and maybe a tad less deflection along the length.

Unless I am not understanding what you plan to do. I envision a piece of barstock 43" long welded inside the tube in the middle vertically? Basically making it look like a pair of 2x2 tubes looking at it from the end?

Like I said, I think they are going to be strong enough as is, but you never did mention what this other tractor is? Adding what you have planned if I am picturing it correctly wont help with strength.

 

[Shield Arc]

LD1 inserting the flat bar has to help some. If nothing else, it's better than a sharp stick in the eye:laughing:. I can't make these welds until I get back around his tractor, to double check the angle of the forks. My forks could not be at 90-degrees. A lot of this will be cut, fit, and tacked, but not welded 100% until I can get back around his tractor.
I can't remember the number of his tractor, but it's around 35-HP.

Did some welding this morning.