Case D100 backhoe

[JSinMO]

You could make the stabilizer legs swing together, under the excavator part and use them for a tongue to tow it with - kinda like the split tail of a towable piece of artillery...

That’s a pretty good idea, and I think it would be an interesting build.

What about hitching the backhoe to the tractor with a 3 point hitch bar and a bolts instead of a hitch pin.

IMG_4429.jpeg (38.55 KiB) Viewed 3274 times

That would give you the benefit of using the heavier lift arms and the weight of the tractor as a counterweight with out needing to change how it’s attached once the hoe is in position to dig. And add stabilizers to the tractor end of the hoe. So you would have stabilizers at each corner of the hoe.
I’m just spitballing here! But maybe there’s a usable idea in there somewhere!

[thebuildist]

great minds think alike? Because I'm thinking along similar lines with the 3pt hitch bar.

Looking at towable backhoes on youtube, most of them set up for a 4-point stance for digging: the two outriggers at the hoe end and some kind of fixed resting pads at the hitch end.

So I'm thinking of that approach: build the precise same outriggers that I've already drawn up (and bought cylinders for)

And then build a pair of resting pads up at the hitch end. Maybe even including a ground engaging spike, to help the pad hold still. And maybe add 300 or so pounds of weight at the tongue, enough to almost balance the hoe end.

But then tow the thing using only the 3 pt arms, not the toplink. Have a 3pt hitch bar that can lift up on or push down on the hitch end of the hoe/trailer, but swiveling so the trailer can turn. So lift up the 3pt arms to drive around. Then downpressure the 3pt arms to begin digging. (I built my 3pt with downpressure.) The fixed weight at the hitch end plut putting the tractor's weight on it should really anchor it in place and allow the hoe to dig/lift harder than most lightweight towable backhoes can do.

The only thing I'm having doubts about is how much of a pain it'll be when you want to move up the trench line. You'll have to raise the outriggers, get off the hoe, get in the tractor seat, lift the 3pt, drive forward, put the 3pt back down, and go get back in the hoe seat, drop the outriggers, and then dig.

Certainly less convenient than having the hoe right on the tractor. But probably not a disaster? And should have similar digging performance to the tractor-mounted type?


Bob

[Harry]

I’ve never seen a towable in use like the ones you guys have mentioned. I have used my 644 lbh a lot this past summer and can only comment on it’s performance. I works well and the hoe is very powerful. Maybe sometimes to powerful. With the GT in the air on the rear stabilizers and the bucket in front with the open end down in the dirt. The hoe will still pull the whole GT towards the hole your trying to dig. So after using it in the same area digging away the GT will stop moving because the stabilizers have been pulled into the ground a few inches and the cutting edge of the bucket also. By now the GT needs to be moved to dig more. With a heavier excavator they probably don’t get pulled by the hoe, especially a tracked one. I also believe a four digit GT with a hoe the rear stabilizers move out away from the GT instead of straight down like the three digit. This would give it more stability when digging. Just some food for thought . That’s my ramble for this morning guys. Harry

[JSinMO]

I’ve never seen a towable in use like the ones you guys have mentioned. I have used my 644 lbh a lot this past summer and can only comment on it’s performance. I works well and the hoe is very powerful. Maybe sometimes to powerful. With the GT in the air on the rear stabilizers and the bucket in front with the open end down in the dirt. The hoe will still pull the whole GT towards the hole your trying to dig. So after using it in the same area digging away the GT will stop moving because the stabilizers have been pulled into the ground a few inches and the cutting edge of the bucket also. By now the GT needs to be moved to dig more. With a heavier excavator they probably don’t get pulled by the hoe, especially a tracked one. I also believe a four digit GT with a hoe the rear stabilizers move out away from the GT instead of straight down like the three digit. This would give it more stability when digging. Just some food for thought . That’s my ramble for this morning guys. Harry

Good ramble Harry. You have a lot more practical experience than I do but in my limited time working the backhoe I have the same experience. It was surprising to me that even with the engine at idle the hoe can easily drag the tractor around. So finding a good way to anchor it is a big part of this. Mine also has stabilizers that move straight down. I also believe outriggers would be much better.

In this scenario I don’t think you’ll need to worry about using the top link Bob. It’s not really doing anything to help.
As far as moving and resetting as you dig it’s pretty much the same procedure if the hoe is mounted to the tractor so I don’t think you’re really at any disadvantage there. I’d b more concerned with finding a good way to pin it to the ground.

[thebuildist]

Good and helpful observations from you both.

I'll be sure to incorporate some kind of ground-engaging cleats on all four ground pads. Maybe I can get clever like Case did and make flippable outrigger feet, one side with cleats the other with a smooth pad.

The other direction I'm thinking is that for the structure of the tongue I think I'll intentionally build it much heavier than I otherwise would. I have from an old project about 400lbs of steel bars that are 48" long, 1/2" thick, and 1 1/2" wide. A while back, to build a front weight attachment I welded them into stacks of about 8, creating laminated steel bars that are about 4" x 1.5" x 48". Each laminated bar weighs about 80 lbs if I recall. I think I'll build the trailer tongue out of a couple of those laminated bars. And I'll sling the rest of them right underneath the front hitch to act as the crossmember for the front ground pads. I'll be silly strong, and I need the weight to counterbalance the hoe's working forces. And it uses up materials that I don't otherwise need anymore.

The only trick is that this hoe trailer will outweigh the tractor itself. So I need to be careful on the hills around here.

Bob

[RoamingGnome]

(ramble warning ) It will be interesting to see the progress of this new direction for your build. There have been lots of good comments made here and the wide variety of YouTube videos let's you see what others have done. From my experience with excavators big and small - I think the biggest force when digging is going to be the bucket and load trying to pull the thing over forwards on its nose. Good long outriggers set as far forward as possible would counteract that shift in center of gravity when there is a load in the bucket. After the stabilizers are set out front extra counterweight on the trailer tongue should add to the stability. Mini excavators have that blade out front more for stability than for backfilling trenches - although that's a handy secondary use....

I understand your concerns about hills too - as my property is basically just one big hillside - I've been pondering the use of electric trailer brakes with a break-away switch so I could stop things if they got out of hand (mostly thinking of this for a log arch I'm planning to build for skidding logs out of the forest - ( my two utility trailers are light weight and don't have brakes)

[Eugen]

I'm going to venture a little input too. First the big backhoe, the Case 680E, which weighs something like 16000 lbs. The backhoe bucket dig force is listed at 16,800 lbs ; it is so strong that even with the outriggers dug in, and the bucket flat on lifting the tractor a little, still can pull the whole tractor in if it gets snagged. Deep dents are left usually where the outriggers touched down.

I had a chance to dig a little with the Kubota B26 as well. The digging force of the bucket is listed at 4210 lbs. The whole tractor is around 4000 lbs too. My take on this is, if it gets snagged, I am not going to try and force it.

Finally, in my opinion the Davis D100 backhoe, is stronger than the Kubota backhoe. The only spec I could find for it was in the trencher manual, and it says 10,000 lbs breakout force!!! I'm not sure I can believe that though. However, I am sure, by the size of the cylinder that it's stronger than the Kubota.

My take home lesson is that whatever you do, the backhoe does have a lot of force and, at some point, it will break your tractor if not treated accordingly.

I have considered many times getting one of those tow behind backhoes. I have made up my mind that it has too many limitations. 1) hard to get in a lot of places, and 2) cannot practically consider that a strong enough platform for a D100. Which is why I was really happy when I found the trencher. We're talking about a really really strong chassis of american steel on steel tracks weighing 4000 lbs. And even this got pushed around by the backhoe when I forgot to put down the stabilizers and dig in the front blade.
My 2c

[Toolslinger]

That 10000# breakout force might be a bit much, but perhaps not. That's the force on the teeth, during curl, when the cylinder has the most leverage. I could see it hitting that number. I don't know that anyone ever made a more robust hoe in such a small size.

Pretty much any hoe will be able to drag itself around, regardless of the outriggers, unless you find a toy.

I think it's a good idea to isolate the forces from your mule as much as possible. I like the idea of the drawbar with ground engagement. The connection needs to be flexible for sure.

[thebuildist]

Again great points made, and my design is evolving a bit further. At first I planned to make the "trailer" tongue "as long as possible" as i mentioned, to give leverage to the "small" weight of the tractor's back end.

Then I decided to intentionally make the tongue out of much heavier steel material.

In the process of drawing that up, I decided that I don't need all that leverage. That "almost 4 feet long" is plenty. Reading @RoamingGnome comments, I've changed my mind back. The trailer tongue does need to be as heavy as possible. AND as long as practical. I'll draw it up with a length of 8 feet from the axle centerline to the hitch pivot. Maybe materials and geometry factors will shorten it up a bit. But I'm going to shoot for "as long as possible." Again, I dont' think it would be useless in the "short" version, but I think the extra length/torque will play to the D100's strength, and make it much more capable. And maybe even make it stable/road-worthy behind a pickup. No guarantees there, but worth considering.

I also had the thought of electric trailer brakes. But because the (perfectly good) wheels and tires I have can't be used on 3500lb hubs (center bore is too small to fit on the hub) in order to do brakes I have to buy new rims/tires in addition to the electric brakes and the new hubs. So the cost difference ends up being over $700. Not in the cards.

I'm currently trying to think of an easily implemented "emergency release" of the boom arm. If you get in trouble on a hill, "drop the boom" and let it drag you to a stop. Maybe some kind of valve piped into the boom cylinder that allows fluid to swap between the chambers? I'll think on it. If the trailer's front pads have decent ground engagement, I could lower the 3 point in an emergency, and those pads will dig in, and do meaningful braking. But on concrete/pavement it won't do much but leave a scrape/scar to show the spot where I perished.

@Eugen's point about damaging the tractor is a good one. My current thinking is a 2" ball hitch mounted in my existing 3pt ball adapter. If the trailer tongue is forced up the the air, it lifts up the back end of the tractor, and no harm done. If the tongue is forced downward, it can't go far, as the ground engaging pads should easily support 10 tons or more. So no harm done to the tractor. So I think the tractor is safe enough, if I can just avoid jackknifing it down a hill. And if I do that, me and the tractor both are in danger. Really. So let's be sure not to do that.

And you're right that this rig probably won't really do justice to the D100. But at this point it feels like either I grab this lower-hanging fruit or nothing at all. And I'd really like to have at least a minimally functional hoe. And in my imagination it SEEMS like it could be perhaps medium useful. But I know that you're probably right. It's probably going to be extremely limited.

But if nothing else, maybe it'll get my ambition/creative juices flowing enough to get me back on track for the original vision.

As of now I have a new drawing and I've ordered a pair of 2200 lb hubs. I'll update with progress as it happens.

Thanks again everyone for your thoughts and advice.

Bob

[JSinMO]

@thebuildist I think flippable outrigger feet are a great idea. I just happen to have broken the pin that holds the foot onto one of my stabilizers. Not sure if you need it but I thought I would post some pictures and measurements for reference.

Overall look the bottom of the pad. It’s made for two spike to attach

Topside of pad

Overall length of spike is 6 inches

Actual possible depth of spike in the ground is 4 1/2 inches.

Pad length 10 3/4 inches

Pad width 9 inches.

Also here are some of the numbers on the D100 hoe from the manual.

That manual is in our technical library here.
Hope that helps!