Designing and Building a backhoe, Need Help!!!!

[RonR]

Personally, I don't think I would ever try to design and build something as complex as a BH. Just building it might not be so bad, but the sizing issue seems a huge risk to me.

If I were doing it, I'd want to make sure I had the EXACT same size cylinders, pins, and dimensions on the steel throughout the BH. If not, it's trouble.

Say that you can't find a cylinder that match. If you have to go undersize just a little, you BH won't operate well. Find a cylinder with too much UMPH, and it might break your joints....

I'd feel safer having a success if I used a kit of hydraulics that have been built previously and size the steel accordingly.

Just my 2 cents.
Ron

 

[firel7]

Ron I somewhat agree with you...but that is why I want dimensions from all the current backhoe owners out there. I have done some research allready including some calculation of forces and I really do believe that it is a completely feasable idea. As for cylinder sizes all hoes of this size class seem to use cylinders of the same size. And basic hydraulics says that given a set pressure and cylinder bore the pounds of force exerted shall remain constant.

I do agree however that steel gauges and dimensions can play a pivotal roll, again, that is why I want to collect as much info about this size backhoe as I possibly can. I could simply follow the caddigger plans and build it but I guess the main reason I would like to modify it is I feel that those designs could afford a bit more structural strength.

I guess if the overwhelming response is that it cant or shouldn't be done I may have to scrap the idea, but it is still to early for that... I don't give up easy, and if there is a problem I really take pride in finding the solution.

Besides, wouldn't it be cool if we all developed a good set of workable and tested backhoe plans, that was designed by the members of this site for the members of this site!?!? /forums/images/graemlins/laugh.gif /forums/images/graemlins/cool.gif /forums/images/graemlins/ooo.gif

 

[khd]

I to have started on this project: backhoe design build but am moving at a much slower pace. I have even started collecting a few things that may or may not go into the design such as a king pin, sleeves and thrust beering from a peterbuilt truck possibly for the boom swing pivot. I also had Ford give us at work a whole bunch of Lincoln Town Car axle shafts. I brought 4 home as they are hardend 1.25" shafts that I am hoping would work for the other pivot pins.

The hoe itself, I think will be the easiest to design. It's the mount to the tractor that will be the hardest. If I tear something up on the hoe that I built I can fix it but breaking something on the tractor would be expensive and hard to deal with. I haven't been able to find any subframe mounts and it's associated tractor mount point examples. I'd be interested in any infor on that portion.

I think the first thing in designing such is deciding what your going to be using it for. Me, I mostly want the design build more than I want or need a hoe so my thoughts are more on a good general purpose desing more that going for max depth or max bucket size.

Land Pride's web site has owner's manual for their hoe and Tractor Smarts parts manuals have Kub hoe parts manuals.

Good luck,

I'd be happy to help anywhere I can.

Regards,
Kevin

 

[mrcaptainbob]

Pricey, yes, but I'd go for a separate pump. Unless you know the pressure capacity and volume so as to compare with the others including Cad-plans....

 

[billbillt]

Have a Cad program here. Maybe could help a little with drawings.

 

[rdln]

If I may point out a few things:

1)If you access to 3d cad software you shouldnt need a cardboard model.

2)Forget about exact pin to pin dimensions, instead decide where and what cylinders you can find and want to buy, that will determine your distances.

3) For crying out loud, you want the softest pins and the hardest bushings, pins are easy to replace, bushings welded on!

If you are serious I can do what I can with my woods 7500

 

[Banjo]

I designed and built a backhoe this past year, and yes I'm one of those Canadian guys over at MBN (Machine Builders Network) /forums/images/graemlins/smile.gif.

There are lots of pictures of what I built, and several threads covering the trials and tribulations of the design process.

I looked at the various plans that were available, but didn't find any that met my needs. The closest were the CDP plans (were a bit smaller than I wanted), and the ubuildit GroundHawg ones.

I've seen some of the CADdigger/CADtrac plans and I wasn't impressed with the professionalism of the plans. Granted lots of people have built to them, but I think they could and should be much better.

The design process was quite time consuming. A good portion of that was the research process, I spend ages trolling the web looking at everything I could find. Those Landpride manuals were useful. I also looked at a good number of commercial units, in fact pretty much any one I saw! It would have been good if I'd had my digital camera during this phase /forums/images/graemlins/smile.gif. I also liked the Shaeff/Terex mini ex boom design, so pattered a fair bit off it. It also looks like the new New Holland mini-ex's are similar, with the boom cylinder on top of the boom.

I should note that I was a mechanical engineer once upon a time, so I could "run the numbers" in a few places. There are some fairly significant stresses in some parts of the hoe (e.g. end of the dipper).

I used 1" pins for all the joints, except for 1.25" for the main boom, dipper and swing pivots. I used two swing cylinders so I could get the full 180° rotation there. I did excel spreadsheets to help design the geometry associated with each cylinder.

I got it "operational" (not finished /forums/images/graemlins/smile.gif ) about a month ago, and used it to dig for the front porch foundations, and to take out some trees. Overall it works very well. I was able to lift a 650# welder, and some big lumps of concrete, so it seems pretty strong.

About the only changes I'd make (so far) would be to go for more bucket rotation ("uncurl") to make it easier to dig small, deep holes (I had it this way first, and re-designed it to have slightly less rotation, but more power /forums/images/graemlins/frown.gif ). I'd also probably widen out the base at the lower end of the boom, to better transfer the swing loads, although I haven't had any trouble as of yet.

I have it mounted on my AC D14 for now (it's also designed so I could use it as a "stand-alone" type hoe like the Ground Hawg (and others)). It was/is a fun project. I probably spend more hours on the design than the build ... certainly very close. I had never used a backhoe until I got mine going, so that lack of experience slowed me down too. I'm pleased with the way it's turned out, and happily it turned out to be quite easy to run. I was able to dig out and lift the concrete after about 30 mins of use!

I've also uploaded a couple of the pictures to the photo albums here. For the rest go to the MBN forum, e.g. Final Progress Topic , there are others in there too (search on hoe), or MBN Backhoe Pictures.

HTH. Andrew

PS. Don't let that Bobodu guy scare you off either ... he's really a great guy and he's in therapy to get over his Canadianaphobia so I hear /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[jmc]

" About the only changes I'd make (so far) would be to go for more bucket rotation ("uncurl") to make it easier to dig small, deep holes "

Banjo,

My bucket has two holes where the linkage attachs to the back of the bucket. Pick one if you want a lot of uncurl; pick the other if you need to lift high, to load a truck, for example. Not having to cover such a large range of motion lets you design the linkage for more leverage. Sorry if you already knew this.

John

 

[Banjo]

John,
yes I know this, but didn't consider it as part of the design and implement it /forums/images/graemlins/frown.gif. In fact my initial linkage design had about 190° rotation and covered both cases, but I wasn't happy (on paper) with the power at the uncurl end of motion.

How often do you find you move the linkage? Actually the only time I've needed the greater "uncurl" was when trying to dig a smaller hole with a vertical back face. One I got down a bit, and had the dipper rotated, I ran out of bucket movement. How much rotation do you get with your hoe bucket?

I think I'm going to redo that part of the hoe when I change over to a quick attach for the bucket. Someone gave me ( /forums/images/graemlins/smile.gif ) a half built trenching bucket, and I'd like to build a wider ditching one (using the old trip loader bucket). At that point I'm going to seriously consider the two holes.

"Experience is what you get right after you needed it" /forums/images/graemlins/smile.gif

Appreciate the insight. Andrew.

 

[jmc]

Andrew,

Here's a picture of how Case does it. I forgot there were 3 choices. Its almost always in the position for the most uncurl. (shown) The only time I miss the extra curl is when I try to dig too close to the tractor.

John