Question about steel strength??

[Creamer]

This looks like a lot time spent on something fairly simple. A couple of years ago I had a shop build me a toolbar with a pair of forks. the toolbar is overbuilt but I wasn't totally sure of what all i would use it for. It is T-shaped of 4x4x0.25" steel tubing and 60" wide. The forks are 3x2x3/16" steel 42" long. They have a C-shaped 1/4" thick plate welded on the base end with a 3/4" hole drilled through on the front side of the toolbar for a bolt to clamp them in place. Now I can have the forks almost 60" wide if I want to or whatever width I want to. Just loosen the 1/4" bolt and slide them. I have had enough load on it that the 3PH would not lift it - no issue for the forks. I have had over 2000#s on the forks and lifted it and carried it.

With this design I use the toolbar for making the raised beds in my garden. I am sure I will come up with other uses in the future but have not yet.

With all this being said the 3X2X3/16" tubing for the forks is plenty as my tractor has more lifting capacity than what the OP has. The question is how the forks are attached to the toolbar or frame. I do not like the receiver concept because of the tendency to concentrate the load at the back edge of the receiver tube. Your forks will bend much quicker with this concentrated loading. that is why I opted for tight clevis with a bolt for attaching the forks. The stress is in shear on the bolts and fully distributed bending.

 

[jodebg]

LD1-

"Top link, I would go for parallel in the top hole. Then using a lower hole will cause the fork tips to pitch up more. "

Think you referring to the top hole-machine side?

Sorry, I was asking about the holes to use on the upper mounting plates, on the attacment.

The attachment upper mounting plates will have 2 drilled holes. I was thinking that when the top link is parallel to the lower links,
I should attach the upper link into the lower hole on the mounting plate?

Changing to the upper hole would have the same effect as if I was changing to the lower hole on the machine side?

 

[jodebg]

Creamer-

Any chance you can post some photos before I have this built?

Would like to see what you did with the forks and how they are mounted. Thanks.

This looks like a lot time spent on something fairly simple. A couple of years ago I had a shop build me a toolbar with a pair of forks. the toolbar is overbuilt but I wasn't totally sure of what all i would use it for. It is T-shaped of 4x4x0.25" steel tubing and 60" wide. The forks are 3x2x3/16" steel 42" long. They have a C-shaped 1/4" thick plate welded on the base end with a 3/4" hole drilled through on the front side of the toolbar for a bolt to clamp them in place. Now I can have the forks almost 60" wide if I want to or whatever width I want to. Just loosen the 1/4" bolt and slide them. I have had enough load on it that the 3PH would not lift it - no issue for the forks. I have had over 2000#s on the forks and lifted it and carried it.

With this design I use the toolbar for making the raised beds in my garden. I am sure I will come up with other uses in the future but have not yet.

With all this being said the 3X2X3/16" tubing for the forks is plenty as my tractor has more lifting capacity than what the OP has. The question is how the forks are attached to the toolbar or frame. I do not like the receiver concept because of the tendency to concentrate the load at the back edge of the receiver tube. Your forks will bend much quicker with this concentrated loading. that is why I opted for tight clevis with a bolt for attaching the forks. The stress is in shear on the bolts and fully distributed bending.

 

[LD1]

LD1-

"Top link, I would go for parallel in the top hole. Then using a lower hole will cause the fork tips to pitch up more. "

Think you referring to the top hole-machine side?

Sorry, I was asking about the holes to use on the upper mounting plates, on the attacment.

The attachment upper mounting plates will have 2 drilled holes. I was thinking that when the top link is parallel to the lower links,
I should attach the upper link into the lower hole on the mounting plate?

Changing to the upper hole would have the same effect as if I was changing to the lower hole on the machine side?

Yes..

 

[franklin2]

You know this thread seems long, but I find it interesting with all the different ideas on the forks and their material. It's too bad all we have to work with is standard steel from the steel mill. It seems to me there is a whole other area that the big manufacturers can use that we can't; Metal that has been formed and folded. And of course the forged forks also. Am I correct in saying a piece of 1/4" flat steel that is folded around in a u-shape would be a lot stronger than a comparable piece of channel?

 

[Sodo]

Am I correct in saying a piece of 1/4" flat steel that is folded around in a u-shape would be a lot stronger than a comparable piece of channel?

Flat plate bent into a channel is probably weaker than the comparable channel. Open sections (channel, angle) are not nearly as strong as closed sections (tubing) for any given weight.

 

[Creamer]

Here are a few pictures of the Forks I had built. The fab shop built this for $400 including paint a couple of years ago. I misstated the fork size in my earlier post - my memory is failing. The forks are 4x2x.156" wall. Also the Cs to attach the forks to the tubes are on top of the tube as shown. As you can see by the photos the ends are all capped for no water, i.e. interior rust. The tips of the forks are tapered as well. I have not weighed them. They are heavy but I can pick the assembly as shown and carry it so am sure they aren't over 150 lbs. I just used bolts for tractor connection for cost reasons but I use them so much I wish I would have put standard pins in.

Picture 1 and 5 are overall views. Pics 2 &3 are close-ups of the Forks attachment to the frame and the connection for the lower 3 pt arm. Pic 4 shows the tapered end of the fork.

 

[franklin2]

Flat plate bent into a channel is probably weaker than the comparable channel. Open sections (channel, angle) are not nearly as strong as closed sections (tubing) for any given weight.

I am not sure I agree. That's why truck frames are not channel, they are bent and formed from flat material. I am sure tubing is stronger than channel, but I was comparing store bought channel to formed channel just as a comparison.

Chevy was using hydroforming to make part of their truck frames(they used to). From what I understand they took a piece of pipe, put it inside a big form, and blew it up with water pressure, expanding the pipe to the form. Besides bending it and forming the frame like you need it, working the metal cold makes it work harden and makes it much stronger than a comparable piece of steel that was "hot rolled".

 

[Sodo]

Truck frame employs channel with strength axis in its "strong" direction. Truck frame also has 'blocking' wherein the opposing channel provides support to create a system strong like a closed section. Also truck frame is highly engineered to provide structure and mounting points for a few other components. . Not to mention higher grade steel. And engineered amnt of torsional flex.

Not really a good comparison because the subject of this thread uses A500 channel in its "weak" direction (wide not tall). The other part of your query was related to steel grades, but I really dont think there are many other options,,,,A500 series is whatcha get. However Rect tubing is often A513 which is a stronger material than the A500 channel, which takes more stress (more flex) before permanent bend.

For a fork tine best bet is a closed section (tubing) or if lift capacity of tractor exceeds intended cargo capacity (+ weight of lift attchmt) then solid section is OK.

 

[ishiboo]

I am not sure I agree. That's why truck frames are not channel, they are bent and formed from flat material. I am sure tubing is stronger than channel, but I was comparing store bought channel to formed channel just as a comparison.

Chevy was using hydroforming to make part of their truck frames(they used to). From what I understand they took a piece of pipe, put it inside a big form, and blew it up with water pressure, expanding the pipe to the form. Besides bending it and forming the frame like you need it, working the metal cold makes it work harden and makes it much stronger than a comparable piece of steel that was "hot rolled".

Well, truck frames aren't channel because you couldn't bend it the way frames bend while keeping the same profile/strength/etc... and it's a consistent thickness vs steel channel where the web tapers. They are also high-strength steel and designed with a certain amount of flex/give in mind. Of course, the highest strength comes from two vertical members... i.e., a boxed frame.

I'm pretty sure the new frames are still hydroformed. The boxed frames I'm pretty sure would have the "boxing" welded in, just as you would do to an existing "C" frame.