Backhoe sub-frame

[currierej]

I bought a used backhoe, somebody had modified the attachment plate for a bobcat QD style attachment.
I'm changing it over to fit on my tractor, I'm building a sub-frame but I have no experience with backhoes or sub-frames. My tractor has a front end loader and I intend to tie the backhoe sub-frame into the FEL structure, my question is where I connect the two, do I want that joint to be ridged or flexible?
Should I plan on one pin (Or bolt) on each side or should I plan on two or more bolts per tab so it is a ridged connection?
I'm not sure exactly what stress loads I'm trying to carry, I've heard horror stories about breaking a tractor in half with a three point hookup, to prevent that what loads is the front of the sub-frame supposed to carry?

 

[JimRB]

The ones I have seen for my little JD870 connect to the rear axle and the posts for the front end loader. You may want to look around to see if you can find the instructions for a JD 8a backhoes, or maybe one of the more modern backhoes for ideas. Or if you live by a Deere or Kubota dealer they usually have a 2,000 pound tractor with a small backhoe on display.

 

[JerryK]

My Bradco designed subframe for my Mahindra has a rigid 4 bolt attachment to the bottom each FEL tower. The main load is carried by the 4 big bolts on each side of the rear axle where the 4pt plates bolt onto. I think the main idea is to try to not put any twisting load onto your tractor in the transmission area, which the tractor is not designed to endure.

 

[N2DFire]

Hopefully dfkrug will be along shortly, he's the sub-frame king of TBN in my opinion.

I missed out on a chance at a Woods backhoe last year, but I have been studying up on building a sub-frame in case another deal ever comes along.

Here are a couple good & recent threads on custom built sub-frames that might give you some ideas for fabricating / attaching your own.

http://www.tractorbynet.com/forums/build-yourself/171760-how-build-your-own-custom.html

http://www.tractorbynet.com/forums/build-yourself/301079-converting-3-pt-woods-6000-a.html

http://www.tractorbynet.com/forums/build-yourself/373738-4pt-mount-bradco-609-mf.html


Good luck with your project. Be sure to update us on what you come up with. I'm sure several like myself will be interested in seeing it.

 

[currierej]

Thanks for the links, the TBN expert pretty much answered my question, in every reference he shows the front of the ladder style frame rigidly attached, so I'll go with tabs and three or four bolts on each side.

 

[Stimw]

I bought a Jinma Hoe and modified the subframe to fit my 3510 Branson.
It mounted to the 3 pt arm mounts under the axle.
On the front it rested on the FEL brackets.
The hoe stress is pushing up at the front of the subframe so I just used some 1/2" all-thread with a hook welded on one end and a "U" type bracket around the FEL bracket.
I also used the top link.
Used it for 12 years and sold it last month!

 

[chriswheeler]

I'd just be careful that the hoe can do self mounting using it's own hyd system. These little 8A's weigh in at 950 lbs. and best way to handle the mount and dismount is using the hoe's own hyd system. There is no pushing these things around by hand.
Chris

 

[N2DFire]

Thanks for the links, the TBN expert pretty much answered my question, in every reference he shows the front of the ladder style frame rigidly attached, so I'll go with tabs and three or four bolts on each side.

I'm glad you found answers. I know all of those throw a lot of information at you.
It's been a while since I read thru them now but if I remember right - the ones that were rigidly mounted were designed as 2 piece frames and the under-mount portion stays on the tractor all the time & the frame separates at the rear of the tractor.

For a one piece frame there are "receivers" mounted at the loader towers that accept the front part of the frame & hold it in place.
Kioti's subframe is this way - this video review of an older model has some really good shots of the subframe and fairly good detail of the mounting points fore & aft and how they mate together.

Both versions are designed to try and eliminate flex / bending in the tractor transmission housing between the axles (typically where they are bolted together and typically where 3pt style hoes break them)


Again, good luck with your project. Definitely keep us updated on your build.

 

[dfkrug]

Both versions are designed to try and eliminate flex / bending in the tractor
transmission housing between the axles

Yes, you want the mount to be as rigid as possible. It will never be as rigid as on a purpose-built
TLB, however.

That's a good video you posted of the Kioti setup. That maker has stuck with the older ladder-style
subframe, while many makers have moved on to the 2-piece subframe.

Also, note that the connection between the tractor and the subframe flexes quite a bit as the
operator digs. This hoe DOES have a connection under the floor for a toplink, but owners often
do not use it. They should.