Need help designing a carriage for a set of forks

[CanDo]

I'm looking for some help in designing a carriage for a set of forks (standard hook-type) to be used on my JD 790. While I've mentioned this on the thread in which I'm documenting the conversion of my pinned loader to a quick attach, I think a dedicated thread about forks or rather fork carriages would be appropriate.

Anyway, the commercial forks and carriages are, although nice, way too expensive and generally far too heavy to be of any use to me. My JD 790 has a Model 70 loader with a bare 750 lb lift capacity at the pins! Subtract the extra few pounds due to my quick attach conversion and then also the weight of the implement (forks and carriage) and you can see that the practical payload of my tractor is not all that great. I do understand that the forces in play would be dynamic (rather than static) so there is that to consider and additionally, if I used the forks in some imaginative way such as to dig out rocks or roots, the breakout force could be considerably more but it would still be relative to my tractor which is quite anemic compared to what many of you have.

The forks I have are 36" in length and are designed to sit on a 16" carriage (from top of upper rail to bottom of the lower rail). They are commercial forks off of an old hi-lo so they are fairly heavy and very strong.

Additionally, I've already gotten a couple of great suggestions in the other thread regarding rollback angle which is something I certainly have to think about and would love to hear what others have done and why.

And then of course there may be something else that I should consider that I've not yet thought about.

So, the bottom line is that I'd love to see pictures of a carriage for your forks that you yourself have built and any comments of what you like or dislike about what you have. Keep in mind that it must be strong enough to do the job but that "light" is good.

Thanks!

 

[CanDo]

To try to get everyone on the same page, I grabbed some of the "fork" discussion off of the conversion discussion and copied them here.

Looking good. :thumbsup:

You may need to build in some extra rollback angle into the fork frame.

... the roll back angle was the hardest thing to get right for me.
In fact wish I had added a little more angle- so that if the forks were used to say pop a small tree or rock out of the ground the forks could be curled back a bit farther to pivot under an in ground object to pop it out a bit more.:thumbsup:

I've been meaning to add some load catchers to the top of my fork frame before my luck runs out and something rolls back and kills me.

These are excellent points that have already given me good things to think about which I very much appreciate. What a great forum!
I do hope to hear from others... especially if you have pictures. I LOVE pictures! :cool2:

 

[dieselcrawler]

I rebuilt this carriage for my friend/former employer about few years ago. 1/2" plate welded to 3" channel for the fork rails, worked out ok...



Edit: I have more pictures of that project if you want them.

 

[mykleh]

I kept it pretty simple square tubing and some flat stock notched welded to it..

 

[CanDo]

Both look nicely done and functional.

I rebuilt this carriage for my friend/former employer about few years ago. 1/2" plate welded to 3" channel for the fork rails, worked out ok...

and

I kept it pretty simple square tubing and some flat stock notched welded to it..View attachment 480715

These both look pretty clean and I think would be easy to put together. :thumbsup:

Dieselcrawler: So, it if you used 3" channel the plate welded on must be .5" x 4"? Looking at it, it looks like it might be perfect for the tractor that it is on, but a bit overkill for mine (I wouldn't be able to carry any real load!)

Mykleh: Similar in concept to Dieselcrawler's... and it doesn't complicated at all. Again, do you remember what size stock you used and also, do you have any idea what your's weighs? Is the frame solid under heavy load or do you have bit of flex? Did you just grind out the notches?

 

[dieselcrawler]

Here is another picture, of the part I built standing up, and attached to the original quick attach part, also homemade, laying on the floor.



Yes, the 3" angle has half inch x 4" plate welded to it, I actually salvaged 4" angle, cut it at the apex, warped the he!! out of it, straightened it out, matched the straight edges so the forks would have parallel edges to fit on, and got it to work... alot of work to save a few bucks and a trip to town to just buy half x 4" flat bar!

This is fitted to a Kubota L4310 with westendorf loader, handles 2400 lbs and lots of abuse well. Your 790, like my 3005, is half or less of that tractor, and could get by with lighter construction. I also tend to overengineer things, for safety, and I hate to fix stuff that breaks.

 

[Leejohn]

Here is how I did mine. They work on the 3 point also.

 

[CanDo]

... alot of work to save a few bucks and a trip to town to just buy half x 4" flat bar!

Yep, but the satisfaction of doing it yourself - priceless!

I always get a kick out of those that recommend just going out and buying something rather than going through the work (and sometimes real struggles) of building something oneself. The sad part is that they really don't "get it" and likely never will. Please understand that this is not a dis of those who buy (as we all do when we have to or even just want to) but rather a thumbs up to the many of you who "build" your own. Over the years many of you have also shared your projects which have then been an inspiration to many of us who been watching and appreciating your efforts and have thus been encouraged to follow (as I have) your examples. Thank you all!

OK, OK, enough of the philosophical rant - back the the topic at hand.

This is fitted to a Kubota L4310 with westendorf loader, handles 2400 lbs and lots of abuse well. Your 790, like my 3005, is half or less of that tractor, and could get by with lighter construction. I also tend to overengineer things, for safety, and I hate to fix stuff that breaks.

Thanks for the extra pictures. Yours certainly looks more than strong enough and way stronger than what I would need. However, like you, I like to over engineer a bit just to cover those contingencies that always seem to come up expectantly. However, as you understand, I have to put something together that hopefully still gives me some real working capacity with my wimpy loader.

Maybe drop down to a .5 x 3 flat bar with a 2x2 sq tube welded on the back or even a .5 x 2 with a 1.5 x 1.5 welded on the back? Support of the vertical forces could even be enhanced though the use of a bit of truss system.

What my main concerns are centered on is the twisting force that a load on the forks would exert on the carriage in addition to the downward force. A load extended out over the forks would also tend to pull the top bar of the carriage out (or forward away from the tractor) while pushing in (or towards the tractor) on the bottom bar.

In addition to looking at a bit smaller bar and backer, I think that the verticals that connect the top and bottom .5" bar assemblies (and maybe even the backers to the bars) could be swiss cheesed full of holes just like an aircraft frame. This would certainly lose some weight while maintaining most of the real strength.

Again, thanks for the pictures and note that I would love to see some more (from anyone) - they certainly help in the conceptualization process.

Don't forget let share what you like and don't like about what you've got.

 

[dieselcrawler]

I was being paid by the hour to fab that frame up, and using the materials as I did was entirely at the request of my boss... the company name is ThistleDew Farm, a play on words for 'this will do', much of the materials used for this and most other projects was largely used/recycled. His response was 'I'd rather pay you wages than buy stuff we dont really need, be done faster, and pay you less'. How could I argue with that?

You can likely see other pictures of that project on my photo bucket account. Will clicking on the picture provide you with a link? If not, I'll post more.

 

[dieselcrawler]

Few more...





One happy bee man...