Case D100 backhoe

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thebuildist United States of America
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Re: Case D100 backhoe

Post by thebuildist »

Ok, I answered my own question: the LBH models are bushed as well, just with a larger diameter.

I'm surprised that they run so much stress on a bushing instead of a bearing.

I suppose I'll just roll with it.

I am updating my approach, though. The cross member with shackles is too wide to slide between the tires.

So I'll take my 1"x4" steel bar and with it laid flat, use it to build a transverse cross member that clamps permanently around the outer bearing bosses. It'll be welded to the bolt-on collars and hang about 1 1/4 inches below the bottom of the differential. I'm thinking that the 1x4 steel is strong enough to handle the hoe's weight and stresses without meaningful deflection. It'll permanently reduce my overall ground clearance by a couple inches, but I won't have to shorten my 3pt hitch cylinder, and the butt end of that will still be the lowest hanging thing under there.

Then the subframe's rails will hook onto and engage that cross member as they slide into place.

Same basic concept, except that the cross member becomes permanent, and only the rails get removed/installed with the hoe. I will have to do some bracing of the rails to keep then parallel and not twisting, but they were going to need that anyway.

In order to ensure good alignment, I'll have to weld up the entire cross member before I drill out and split the collars, and the collars will have to be line bored. I think I can JUST fit it on my lathe and do the line boring there. If not it'll be a real challenge.

So next I make a trip to pick up the steel, and figure out my contraption to machine the od of the axle housing. And start fabricating a shaft for line boring.

Bob
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Re: Case D100 backhoe

Post by DavidBarkey »

thebuildist wrote: Thu Mar 30, 2023 12:25 pm I'm looking in the transaxle service manual to figure out where, exactly, the outer axle shaft bearing is located.

And I think I'm seeing that it only has a bushing. Is that correct, the rear axles are in bushings, not bearings? Do the lbh transaxles have bearings?

Bob
All 200 and 400 series I have worked on have been Bushings . I would suspect because low speed high weight capacity the loader / BH are as well .
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Re: Case D100 backhoe

Post by thebuildist »

Ok, opinion question. Put on your engineering hat and tell me which of these is better:

There will be a 1" x 4" steel crossmember that is "permanently" bolted in place, running under the rear differential, and bolted to collars around the ends of the axle tubes.

The full weight/torque of the hoe will hang from this crossmember when your driving around. The hoe hangs on the crossmember, the crossmember hangs on the outboard wheel bearings and axles, where the load is transferred pretty much straight down to the ground.

The question is about the bolting: The collar going around the axle housings is 2 inches wide, made of cast iron. A set of 4 bolts will run vertically, clamping a big sandwich consisting of, a 1" steel plate on top, then the two collar halves, then another steel plate (needed for spacing) then the 1" thick crossmember itself.

The challenge is that the collar stack is 5" wide, because it has to wrap around the housing, which is 2 9/16 OD. But the transverse crossmember is made of 4" wide bar (I cannot affordably buy any wider). So the collar stack is an inch wider than the crossmember, when looked at from the side. And when you run a pair of bolts on either side of the axle housing, those bolts spread out to around 4 inches wide, too wide to bolt into the 4" steel crossmember.
image.png
To mitigate that, I could weld strips on the sides of the crossmember, but I'd rather not. It'll be a real pain to get it flat enough and cleanly enough welded through that I feel confident about its integrity.

There are, however, two different bolting strategies I can persue, bot fairly affordable (around $35) (It's surprising how expensive bigger hi-grade bolts are!)

The first is that I can use 8" grade 8 bolts, drilled at a bit of an angle, so that the bolt heads are closer together than the nuts/washers are. Fot $35, I can get 8 coarse thread bolts, enough to do the whole thing. I'd torque the top nuts to something like 130 ft-lbs, and each bolt is plenty strong, about 17,000 lbs yield apiece. But I have to massage the seat for each bolt and nut so that it's bearing flat against the substrate, and because it's slightly angled, the true vertical clamping force is lessened down to something like 14,000lbs per bolt. Still a whole lot of force.
image.png
The second is to use big square-bent U bolts, a pair of them, one facing up, and the other facing down. For $35 I can get a set of 4, 9/16" fine thread, grade 8 ubolts, 3" wide. The 9/16 fine thread bolts have a whopping 23,000lb tensile strength, when torqued to 180 ft-lbs. And they're installed pure vertically, for maximum net force on the "stack". But I'd have to make some kind of insert to accomodate the fact that the "square" bend isn't perfectly square. If I just stick it into drilled holes, the "u" section will stick out, and I need it to seat flat. So I'd have to fiddle with that. And because the holes are too wide for ends of the 4" crossmember, I'd have to add an additional 1/2" or thicker steel plate to kind of act as a keeper/washer, so that the bolt heads aren't just sliding off the outer shoulders of the crossmember.

(you might ask, why don't you use straight Grade8 bolts and nuts and put a keeper plate under the bolt heads. The answer is, you can't affordably buy them any longer than 8 inches, and adding the keeper plate pushes it to more like 9 inches minimum.)
image.png
The third option is to run a single set of 5/8" fine thread grade 8 u bolts on each side. basically the same photo as above, but instead of having an inboard and outboard set of u bolts, there would just be a single ubolt on each side, I think located off-center inwardly, because the torque is trying to peel away the inner side of the joint more than the outer. About 26,000lbs tensile strength.

About the same overall cost, less complexity to drill/install, and the parts not as tightly crammed in there as the other two solutions. It seems a little more elegant overall. If I could afford 3/4" ubolts like this, I'd do that for sure. But that cost jumps up to around $100, and I don't think the extra $65 is necessary.

So I guess I'm leaning towards the U bolts, and the 9/16" U bolts in particular. When I imagine all the scenarios, the U bolts seem more stout, more secure, and I think 4 9/16 bolts must have an edge on 2 5/8" bolts.

But I'd love to get you folks' opinions, especially if anyone sees something that I've missed.

Bob
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Re: Case D100 backhoe

Post by Spike188 »

Bob, you have my full attention. I am just trying to figure out how using your idea and machine constraints and how I might do it. Because there is a 646 here in the bone pile that is broken in half and came with a bent under carriage, your putting time and thought into the build is a good idea. I will sleep on this tonight and maybe wakeup with an idea, not.... But I did get out the Macmaster Carr catalogue. :j
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Re: Case D100 backhoe

Post by DavidBarkey »

@thebuildist Bob I am a firm beleaver that overkill is underrated . But I think you are taking it up a notch . I assume you are using cast iron blocks for easy machining , I would use leaded steel . The 1x4 is a good idea because it is on it flat . But I would also put tabs on to pick up the mounts for the sleeve hitch to tie the diff. together . As for the mounting blocks at the tube ends I would go with 1/2" plate on top and truck axle U bolts . But on the bottom have the 1x4 directly under the iron block with a 1/2" clamping plate . The only real load will be on that point when driving around . The outriggers will take the majority of the load when down . There are back hoes bigger than that one that hang off nothing but the 3pnt. hitch . example .
image.png
I have worked on larger tractors with bigger back hoes and the frames are held in pace with 1/2' u bolts and 1/2 plate with no issues . Look at some of the back hoes in that size range and what the different manufacture are using for the sub frame and to mount it . You will be surprised . Then just up it a bit for piece of mind . Thats what I do because I know the engineers cheat the lower limits . The bigger and heavier you make everything is going to further add weight stress on the machine . As for front weight , do you have room in front of the axle down low . I am thinking a weight that would slide into a receiver hitch welded to the front of the subframe . You could use the loader to help lift it into place and then lock in place with a pin . I hope this helps more than muddy the waters for you . You smart guy , you will figure it out . I Am sure of that .
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Re: Case D100 backhoe

Post by thebuildist »

Thanks, @DavidBarkey that's all good advice.

I do plan to tie the center of the crossmember to the transaxle, as you mention. I just mentally want to be sure that I'm not asking the transaxle to carry any weight/shock load.

I agree that leaded steel would be the best choice for the collar, but I have cast iron in hand, and I think it's good enough.

I'm surprised that the steel cap and bottom plate could be 1/2" instead of 1", but now that I think about what you said about larger backhoes, I guess you're right. So 1/2" it is.

Do I understand you to say that a single 9/16" ubolt would be fine? I could imagine that. Would you guess 9/16, or do the 5/8" for that "overkill"?

The only tricky part that I anticipate is that I'm going to have to shim between the collar halves: I'll machine the collar in a single piece, then bandsaw it in half. But if I don't shim between the halves, I think that U-bolt may actually crush/deform the axle housing. So I'll need to shim it enough for it to be snug, but not so tight that it crushes. And that makes it all the more important that the crossmember be tied to the differential in the center, to be sure that it never rotates forward or backward out of the desired flat position.

To bend the 1x4 steel bar I intend to heat it up with a rosebud and put it in my electrified 20 ton press. It's going to be a challenge to get the bends just right, both for their location and their degree. In the past my guesses/horse sense for where and how much to bend haven't been terribly accurate. And once you've put a bend in, it's very difficult to take it back out and start over, so I'm going to try to do some youtube research for tips and draw up a specific bending plan with dimensions, to where I can work to a specified measurement and hopefully get it very close to perfect on the first attempt.

Bob
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Re: Case D100 backhoe

Post by Spike188 »

backhoe warning.jpg
This is a warning found in a Case backhoe manual but I have not been able to locate which one it came from. The point is that the Case under carriage design did not address flex of the frame from stresses applied to the loader tower mounts and the backhoe. Dave has a good point in that the rear axil stress as Case designed was only during transport. Using u bolts or clamping systems from trailer axils seems like a good alternative or source for mounting options.

The previous owner of my 646 backhoe ran the differential so low on oil that the axil eat through the outer bushings, and wore into the casing about 0.100". The stress on the bull gear was enough to break the axil spline off of the bull gear. My thought is that if proper periodic changes of oil and maintaining oil levels the bushings would not have degraded to the point of complete failure.
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Re: Case D100 backhoe

Post by DavidBarkey »

Do I understand you to say that a single 9/16" ubolt would be fine? I could imagine that. Would you guess 9/16, or do the 5/8" for that "overkill"?

Me I would go for 2 - 1/2 u bolt on each side .

The only tricky part that I anticipate is that I'm going to have to shim between the collar halves:

Me , I would rough machine to with in width of cut . Then cut in half put haves back together and finish machine to about .010" undersized . Mark halves so alignment and pairs can be identified .
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Re: Case D100 backhoe

Post by Eugen »

Here's a pic of the big Case 680 transaxle and how it's bolted to the frame. The 4 bolts are 5/8. The backhoe on this is massive. Only the bucket weighs as much as the D100 most likely.

3ACBAB43-96F4-4B70-AAAB-BB6C685F3C41.jpeg
If I were you I'd consider securing the cross member to the transaxle in more points such as the sleeve hitch attachment screw holes, and possibly the two top bolts where the 3pth connects.
5BC976AF-CEAB-402A-86AA-1EA3AAA0929B.jpeg
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Re: Case D100 backhoe

Post by thebuildist »

You see that? THAT is why it's so nice to have this forum with smart people. OF COURSE I should rough-machine, then split it, then final machine it. Great point.

Bob
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