Adjustable tooth bar

[bcarwell]

Hi all,
I am building a toothbar for my Kubota 7500 FEL. It has limited power (24HP, 600 lbs lift in "theory"). I have lots of rock I need to get out of the pasture and am told I may not have the power to run a conventional rock bucket. So until I try I don't know how many teeth on a tooth bar I could handle, how long they could be before I bogged down rooting rocks out, etc.
So I saw the need for a tooth bar where I could space the teeth experimentally easily to see what works best and in whatever job I'm doing- rooting and picking up a few big rocks with a few longer teet, scraping up more smaller rocks with smaller, closer spaced teeth, etc. And I might also like to just add two long teeth to serve as two forklifts for lifting a small stump or whatever.
So what I'm thinking of is the following I'd appreciate some comments on regarding feasibility, stupidity, etc. I can't afford lots of different implements and thought with this setup, I could fabricate all kinds of different teeth as needed and install them quickly.
Basically its a regular toothbar plate maybe 3/8" at "A". The ends are bolted through holes in the FEL at "D" just like a regular add-on toothbar plate near the front lip of the bucket. A pipe "B", maybe 1 1/2 inch is supported by two slightly larger short pipe pieces "C" welded to the end brackets of the toothbar. I then add as many teeth E as desired and of desired length for the given application by sliding them onto the pipe B before installing the toothbar plate. The important point (not shown) is that I can also slide short lengths of pipe like C onto the pipe B to serve as spacers between the teeth E so as to space the teeth any desired distance apart.
I also might weld some permanent shorter teeth (only one shown as "G") to serve as conventional toothbar teeth since I've already incurred the cost of the toothbar A (and also in case the design of the adjustable teeth is a disaster). If I'm digging up big rocks, I might just put two longer teeth E on. If I'm scraping shorter rocks I might, instead, use more teeth spaced closer together to act like a conventional rockbucket teeth where the dirt can fall between the teeth and I can tip the bucket up to deposit the rocks in the FEL bucket.
Anyway, hopefully you get the crude idea (sorry about the lousy drawing).
I'd appreciate any comments, suggestions, or indications I'm certifiably nuts.

Bob

 

[bcarwell]

One thing I forgot to add is the smaller support pipes "C" obviously need some way to open up to allow ends of the pipe "B" to be inserted or removed when changing out teeth.

Also, one perhaps unobvious benefit to the idea is that you can rotate as many teeth "E" upwards out of the way for different applications, including rotating all of them up to expose just the little permanent teeth G yielding a conventional toothbar.

 

[KJM]

Just one comment - bucket teeth transfer the load to the bucket both via the "toothbar" as this forum has christened it and via simple mechanical wedging onto the bucket lip. Seems to me your design puts the load entirely onto the pipe support? Looks like that'd be bent pretty quickly - especially if you extend the teeth (which will increase the moment on the pipe significantly).

So part "E" needs some kind of bucket-edge-engaging hook doofer under it. You could probably modify tooth adaptors (shanks) for this purpose?

Cheers
/Kevin

 

[jmc]

Robert,

Before I saw your occupation in your profile, I thought that your description read like a patent!

I'd be concerned about bending pipe B as well. Right now you have that pipe constrained in all directions such that it must be assembled axially. If you would cut away the fronts of pipes C, you could assemble it from the front, a direction that shouldn't see much dislocating force. A simple retention pin may be all that is required to keep it seated in your C pipe mounts. One of the things this would let you do is have one or two additional fixed supports along pipe B to dramatically reduce the unsupported span subject to bending. Of course, these additional supports would have their fronts relieved too.

Another consideration may be that when you turn while using this, or hit an obstruction obliquely with tooth E, there will be a lot of stress on E/F welds since there is no lateral support at the lip.

Hope you post some pictures of what you finish up with.

John

 

[bcarwell]

I guess after fiddling with patents for almost thirty years it shows...
Thanks guys for taking the time. I really needed to know where the weaknesses were and you spotted them. I think cutting the front of the support pipe brackets out is a great way to pop the pipe/teeth assembly on and off for altering the teeth arrangement without sacrificing strength since the forces obviously as you noted will be mostly backward and upward- a little simple pinning should keep the assembly on.
An additional support in the middle welded to the horizontal tooth bar should relieve some of the stress on the pipe ends to avoid the hassle of having to put "hook doofers" on each and every tooth. And making the pipe piece that the tooth is welded to a little wider that the tooth so a gusset can be added on either side of the tooth welded to the tooth and pipe piece should address the lateral force issue.
The need for this was reinforced today as I was using my compact tractor and box blade to put in my lawn. I had to keep adjusting the number of teeth in the box blade and depth as work progressed since, with only 23 HP, the tractor bogs down in the early stages. I'm sure I'd run into the same problem with a conventional fixed toothbar...
I hope to post pictures when I get it done but alas don't look for anything soon, as I will be in China for the next few weeks...
Thanks again,

Bob

 

[KJM]

I'm still a bit worried that the entire load is being transferred to the bar/tube. The front-of-bucket engaging "doofers" (sorry for using such a technical term ) take most of the load to the front of the bucket (which is engineered to take it). I have a really baby tractor - a Kubota B7100 - and I think if I used your proposed design with it, the bar/tube would bend if I hit a substantial rock. The forces involved are pretty substantial.

My own toothbar is 12mm (near enough 1/2") by 65mm (2.5") and takes almost no load - the tooth adaptors transfer the loading to the reinforced bucket edge. Despite this, I have bent the bar - buried rocks are a pain! And all this with a 1200kg (2500lb) tractor and a truely awe-inspiring 16HP!

/Kevin

 

[bcarwell]

Yikes, Kevin, you have convinced me. I have a Kubota 7500 with a "hefty" 23HP. I think I was making a mistake in looking at tooth bars that appeared to be just mounted with bolts on either side of the bucket. In reality, in looking closer now, they're like you described with each tooth having a "doohicky" going underneath the bucket's leading edge so as to distribute the load all along the edge. So I'll continue to play with it- maybe having the upper toothbar extend a little out from of the bucket lip and welding to it another smaller toothbar extending across the lower surface of the bucket lip. I remain convinced however that I need flexibility in easily being able to change out, depending upon the job, the number and spacing of teeth and their length without having to own multiple tooth bars. More spaced apart and shorter teeth for regular dirt digging like a conventional toothbar, closer and longer when trying to pick up surface rocks and let the dirt fall through a la conventional rock buckets, and maybe just two much longer ones that can serve as mini-forklift forks for just lifting stumps, big rocks, etc. Anyway, thanks for your healthy well-founded skepticism. Not so much an issue when you have a big tractor with horsepower to spare. But I've had to go down to just one tooth on my box blade at times when I'm going over particularly compacted or rock-infested ground or I stall out. I'd hate to sink alot of $ into a fixed toothbar only to find half the time all I can do is lightly backdrag with it.

Bob

 

[MrJimi]

Bob, I'm sure you have seen the bolt on forks for buckets, about you make some bolt on teeth and I think that would work great for you
Jim

 

[workinallthetime]

Yahoo! Photos - workinallthetime's Photos - kubota bx23 2005 model

I dont know if you have looked at my redneck built tooth bar but here is the think to the pics. I found a foundry here that makes the teeth and bought them for less than what the ones cost at the dealer. I spent 191.00 for all 5 teeth, shanks, and pins. I am amazed at how well it works, the teeth i used are much larger than most of the production models for my bx23. The extend way under the bucket and have a wide tooth. My soil is mostly hard packed clay with lots of sandstone. I have used it on gravel packed driveways and in the clay, the thing works great !! its pretty heavy and it transfers the load sometimes out farther then the w/o the teeth. If you are working in alot of small rocks you might also want to look at the grade blade i made for the BH, you just slide it across the surface and it does a great job of organizing all your rocks into neat piles so you can pick them up with the FEL. As for making the teeth ajustable i would think you would have to pin each tooth in 2 places to ensure it doesnt move on its axis.