how to build your own custom backhoe subframe

[dfkrug]

Here a tube video on a other Italian brand with side shift were you can see how its work.

I see how that works. The only side shifting attachments I have seen in
the US are on skidsteers, which also had the vertical outriggers. That
seems quite useful in cases where you have to get very close to the side
of a building.

 

[mjncad]

I like the transport position compactness of the side-shift backhoe, along with its ability to dig near a wall, fence, etc. It seems that it would be easy enough to add swing down USA style outriggers to complement the vertical outriggers for close quarters work.

 

[dfkrug]

The design of the seat and the seat support is very important for good
ergonomics and a very close-coupled hoe. This is relatively easy to do.
The hoe manufacturer often has a compromised subframe design that uses
a seat and mount that clears any POTENTIAL objects in its way. A better
subframe uses a seat and mount optimized for a particular tractor.

The Prairie Dog comes with a very nice large seat, but I find it to be too
big for a close-coupled hoe. For my last 5 subframes, I have gone with
a much smaller seat, like the garden tractor seat in the photos. This is
a generic polyurethane seat from AgriSupply, with a steel core and many
threaded mounting holes.

I fabbed a seat support pan, and adapted the existing telescoping tube
for height adjustability. The resulting mount allows the seat to fold up
and fold down to rest just above the hyd oil fill port. I can easily reach
the hoe controls from the driver's seat, also, as when I want to reach
around to lift the outriggers.

 

[dfkrug]

Here is the final installation.

You can see how close-coupled the hoe is to the tractor. The step has
even been trimmed back to allow 7/8" clearance to the tire. The more common limit to how close you can mount the hoe is the clearance between
the tires and the outriggers.

Two underside views of the tractor show how well the subframe integrates
with the tractor's carcass. There is negligible loss of ground clearance,
and better protection of the sensitive hydraulics.

 

[mjncad]

Very nice work!

 

[dfkrug]

Some final notes:

I like to reuse steel that I have, often recycled from leftovers and
other free salvage that I have lying around. I prefer bar stock and
channel, over tubing because pound-for-pound, bar and channel will have
thicker sections which allow for stronger welds. The cost of new steel
is reasonable, however. There is only about 135# total weight of this
subframe.

Each hoe attachment has its own requirements for ground clearance of the
hoe itself. This constraint (12-14" for the Woods 7500/PD7.5) will have
a big affect on the subframe design.

Later, I will post some pix of the 4300 with hoe and FEL mounted, all
cleaned up.

To summarize, here are some suggestions for making subframes:

> Mount the hoe as close to the tractor as possible, limited by the tire-
to-outrigger clearance. Completely modify the seat support to clear
obstacles....only let the seat support control how close-in the hoe is
mounted if the fuel tank is in the way.

> Attach the forward parts of the subframe forward of the tractor's
center-of-gravity.

> If subframe rails are not straight, add cross-members for rigidity.

> For removable connections, use bolts for the strongest, tightest
connections. Loose connections (e.g. pins) lead to hole distortion.

> If the tractor allows, make the subframe wrap around the rear axle and
connect at 4 removable points.

> Use bolt hole alignment aids to assist with mounting the subframe.

> Use existing threaded holes in the tractor's castings when practical. But
do NOT use holes or pins that are required by the 3-pt hitch lower arms.

> Subframe supports that are outboard-mounted are superior to those that
are center-mounted.

> Since manually tightening attachment bolts is difficult, weld the nuts to
the frame member so only one wrench is needed. Check tightness often!

 

[Baby Grand]

Dave,
Thanks for a great, illustrated primer - you could write a book about this. You have identified what you see as the primary design concerns and described how the solutions should address them, rather than getting bogged down in specifics. This give us a very clear plan about what to focus on to get a great install on various hoe/tractor combinations. I'm looking forward to reading about your 4300 job.
-Jim

 

[dfkrug]

Thanks, Jim and Matt and everyone else who has given me all the positive
feedback in posts and PMs.

I hope that anyone sitting on the fence about this kind of project will be
encouraged to proceed. The forces are large, but the project is really
not difficult at all.

 

[Iplayfarmer]

...I hope that anyone sitting on the fence about this kind of project will be
encouraged to proceed. The forces are large, but the project is really
not difficult at all.

You got me convinced. I've been planning a backhoe project for a while, and the part I was having the hardest time figuring out is the subframe. I'll visit this thread often as I build mine.

 

[arrabil]

Yep, no more concerns over those stupid quick attach plates Deere uses on the 4200/47. Just gonna make a subframe when I get one.