how to build your own custom backhoe subframe

[dfkrug]

The forward to aft dimensions were spot on, otherwise I would not have purchased it.

That's very fortunate. Since you got rid of the Prairie Dog, what hoe
are you going to use?

 

[dfkrug]

An integrated TLB, like the Kubota B21, provides an illustration and a
paradigm for hoe attachments to CUTs. Here we see how the subframe
couples the front to the rear of the tractor, while providing structural
elements all around the rear axles, and 4 mounting points. The B21
hoes mount and dismount VERY quickly thru the use of pins and clamps.
You can see the clamps and the huge 1.5" pins in the photo. This
so-called "mainframe" weighs only about 200#, and it exhibts very little
flex under stress.

There is some wiggle, however, which is the only criticism I have for
this design. Although the pins are securely attached, I noticed that the
bolts that hold the clamps tended to loosen up with vibration AND they
can not be easily monitored while the hoe is mounted. So even the
very clever Kubota design is not ideal, and it would take additional hours
of fabrication time to copy.

The hoe is mounted very close in, with little space between the outriggers
and the rear tires. I have several hours of seat time on the B21, and it
is impressive, but the very light weight allows it to be dragged easily by the
hoe, even with only 2000 psi hydraulics. Weight is your friend when digging
holes.

Anyone contemplating their own subframe design and fabrication project
should go and look at these integrated TLBs, as well as other excellent
designs, like the Kubota BX24/BT600 or the Grand L/BH90.

 

[dfkrug]

Those who follow my ramblings on TBN have seen some of my earlier
custom subframes. The first I did was of the ladder frame with toplink
style, but I used a permanently-mounted subframe that disconnected
from the hoe with bolts at the lower 3PH hoe mount. So I preserved the
lower 3PH mount on the hoe, but instead of using the 3-pt arms on the
tractor, I used rigidly mounted arms, which were shorter. This allowed
the hoe to be almost a foot closer to the tractor, and no 3PH anti lift
brace was needed. I did use the enhanced toplink. Sorry, but I have
no pix of the subframe.....this project was a long time ago.

 

[Reg]

I don't know where this fits in the scheme of sub frame types, but I have a Kukje tractor that has a Humpolec loader frame that goes all the way back to the rear axle where it bolts together with and under the ROPS.
The Amerequip hoe sub frame mounts to the bolts that normally support the 3pt lift arms and at the front hooks over a cross member of the loader's sub-frame.

It works (-:

 

[dfkrug]

The Amerequip hoe sub frame mounts to the bolts that normally support the 3pt lift arms and at the front hooks over a cross member of the loader's sub-frame.

You bring up a good point, REG. When practical, it makes a lot of
sense to tie a backhoe subframe into the loader subframe. This applies
to custom subframes or ones that come from the hoe vendor. The
B21's "mainframe" above is for the hoe AND the loader.

Also, TBN members will notice that some tractor makers, like Kubota,
put their FEL subframes under the the tractor, while others, like JD,
put the FEL subframe mostly above the tractor's main structure. I
know I am generalizing, but the former type allows you to integrate
the two subframes together. Woods usually requires a tractor mounting
one of their hoes to have the factory FEL or a Woods FEL. Use of
other aftermarket FELs may interfere with or not connect to the Woods
subframe.

The photo is of a Grand L 40 with the BH90 subframe and how it is
attached to the FEL subframe.

 

[Reg]

I am fairly sure (from tractor shopping) that just about all backhoes require a FEL frame to be installed first, at least the ones that I got anywhere close to considering required it.
I didn't consider 3pt hoes.

When I put the Amerequip hoe on mine the first time I had to squirm around under the tractor and loosen a lot of FEL mounting bolts, leave a lot of the hoe sub frame bolts loose, assemble it all, then "shake in place" for it to align and fit.
I had bought the hoe some time after the tractor from a different source, hauled it home several hundred miles in a (half clean) horse trailer, a fun project in itself (-:
I might as well state here that the Amerequip hoe is definitely owner installable with only nominal hand tools, no need to pay a dealer to foul it up when you can do it right yourself (-:

 

[o2batsea]

Going hand in hand with all this is ease of installation and use. While having a firm attachment system is great, if it is difficult or impossible for one person (sitting in the driver's seat) to back up to and hook up...well, it's not worth bothering with.
This is the balancing act the designers must struggle with. I know the BH ladder type subframe for my Kioti DK45 isn't all that great (kioti BH). I wouldn't want to use it all day every day, but it sure is easy to hook up.
One that requires crawling under the tractor, installing bolts and other calisthenics should be considered as poor design, in my book.

 

[Iplayfarmer]

Going hand in hand with all this is ease of installation and use. While having a firm attachment system is great, if it is difficult or impossible for one person (sitting in the driver's seat) to back up to and hook up...well, it's not worth bothering with.
This is the balancing act the designers must struggle with. I know the BH ladder type subframe for my Kioti DK45 isn't all that great (kioti BH). I wouldn't want to use it all day every day, but it sure is easy to hook up.
One that requires crawling under the tractor, installing bolts and other calisthenics should be considered as poor design, in my book.

This may be what you meant, but I think a moderately difficult subframe installation is tolerable as long as connecting/disconnecting the hoe itself is doable by one person in a few minutes.

 

[dfkrug]

I am fairly sure (from tractor shopping) that just about all backhoes require a FEL frame to be installed first, at least the ones that I got anywhere close to considering required it.

Most are probably that way, but on most JDs, the subframes don't touch
at all. Of course, putting a hoe on a tractor with no loader at all (or
no front weights) is a mistake, esp with small tractors. All that weight
in the rear with no counter balance up front makes the steering control
very dicey. I have tried it.

Anyway, here is another JD example...this time a very common 770 with
a brand new JD7 mounted to an undermount ladder-style subframe. An
enhanced toplink with a brace is used. The QA mechanism and cross-
brace (rung) in under the tractor ahead of the axles.

 

[dfkrug]

The next subframes I made were for the JD 955, a much smaller tractor.
Both involved a hybrid subframe that was similar to the ladder subframes,
but also had structural elements that surrounded the axle housings. There
was no toplink used....the toplink brackets on the 955 are very small
anyway. Here are some pix of the 2nd one I did. The first one was a bit
different from this one, but I have no pix. I was on a learning curve.
The 955 was a great laboratory because I had several that I refurbished
and the low height of the rear axle housings was ideal for the ideal
mounting height of the hoe. The bottom of the hoe should be 12-14"
off the ground, primarily based on the outrigger design.

The result of this 2nd design was a very close-in hoe that worked very well.
Because the tractor was so light (less than 2000# naked), the hoe could
drag it very easily. The same hoe on the other tractors I did were much
more productive, due to 50% or more tractor weight.

In the photos, you can see that I used channel steel that was welded up so
that it fit precisely around the housings, which were made of cast steel. I
could not have done this if the housings were aluminum. All of the subframe
was permanently mounted to the hoe, with a forward connection to the
tractor frame at the mid mount mower bracket. It was very easy to mount/
dismount, which required the removal of the front 2 bolts and the
rear 2 bolts.

As an aside, the 955 with hoe and loader was very similar in size and
weight to the B21. However, the 2500psi hydraulics and AG vs. IND tires
made the 955 a much more productive TLB, IMO. The 50% greater
engine power was also a plus, but second to the other factors.