making a subframe for my 01 John Deere 4300 and Prairie Dog backhoe attachment

[dfkrug]

Well, I recently finished another backhoe subframe. This may be my seventh or
eighth? I lost count.

This is for a 2001 John Deere 4300, and a new Prairie Dog 7.5, a Woods 7500 clone.
I recently rebuilt this former rental tractor; the thread is here:
http://www.tractorbynet.com/forums/parts-repairs/247806-2001-john-deere-4300-hst.html

Unlike the last subframe I wrote about, which was for the same model tractor
and hoe, this one is considerably different. Followers of my other subframe
threads can compare/contrast to my last 4300 effort here:
http://www.tractorbynet.com/forums/build-yourself/171760-how-build-your-own-custom.html

I did this subframe differently than the last for a couple of reasons: one was to keep
me interested. I don't really like to do repetitive stuff. The other reason is to show
that no single approach is better in every way. One way might be easier to make,
but harder to live with. Another might provide more durability, or one may be easier
to mount/dismount.

Anyway this one is sort of a "Five-point subframe". It will be made in two main
parts, a tractor-side ladder frame that stays mounted all the time. And a hoe-side
frame that is permanently mounted to the hoe. The tractor side will not interfere
with the 3-point hitch, and will provide some underbody protection to the exposed
hydraulic lines. Hoe mounting/dismounting will be much easier than the other 4300
subframe, which was one piece that always stayed mounted to the hoe. The
new subframe will mount/dismount using only 2 bolts and one pin.

First, I will post the DONE photo, showing how close-coupled the hoe is to the
tractor. This one has the best departure angle of any I have done, with minimum
tire-to-hoe clearance. Works great.

 

[Stimw]

That's a good looking Hoe! (can I say that here?)
The important thing with a subframe is that it protects the tractor center from the stresses.
I got a great deal on a new closeout Jinma Hoe on ebay ($2200.) and modified the subframe to fit my 3510 Branson.
I have a Welding/Fabrication Shop so it wasn't that bad of a project.
The Jinma Hoe does OK but I wouldn't want to make a living with it!!!! I do have fun with it and it beats a shovel! I also made a 6" bucket for it for trenching which works great.

 

[dfkrug]

OK, the plan is to use some 1.5x3.5x1/4" channel, which I have salvaged from
a now-defunct tractor dealer. (They were from Kubota shipping crates.)

These main rails will be welded to the lower ROPS bracket in the rear, and
hang from existing holes in the tranny tunnel up under the foward middle
of the tractor. I cut some 1/4" plate for the forward brackets and drilled them.

I plan to attach all the bolted elements to the tractor, position the welded
elements, then tack-weld them while mounted/positioned on the tractor.
Then I will remove all the bolts to do the final welding.

 

[akraven]

I will look forward to seeing how you design and build this. On the list of things I want to do to my tractor.

 

[dfkrug]

Here is the subframe after I tack-welded it, then unbolted it from the tractor.
I like to use a series of small automotive-type scissors jacks to fine-position the
channel steel before tack-welding. They are strong, secure, and are
hand-adjustable.

The forward section uses some shedule 80 pipe for transverse support. The
rear support uses some 1/2" plate welded to the frame channel, and the
ROPS lower bracket.

The 1/2" plate is the only steel I had to buy.....I never have too much 1/2"
plate lying around. I bought a 4' long chunk of 4"x10"x 1/2" angle steel
as the salvage yard for .35/lb, or about $35. Part of that is for the hoe-half
of the subframe, coming up.

 

[dfkrug]

Here is the tractor-side of the subframe all welded and painted.

On the forward supports, I boxed in the channel for strength.

On the rear, I added some 5/8" bar at 45-degrees to the channel. This will be
the only place where the subframe is bolted to the hoe-side subframe. I drilled
the 1" hole first, so I could use my drill press. These holes will have SAE
grade-8 1" bolts. (Sadly, hardware stores around here no longer carry one-inch
fasteners, so I had to go to Fastenal.)

Below the bolted element, I made a cradle in the channel to support a 1.125" guide
pin. The hoe-side pin will rest in this saddle, and the hoe will pivot upwards to align
the bolt holes. It will be clear in later photos.

 

[dfkrug]

Here the tractor-side subframe is mounted to the tractor.

The forward section uses existing holes in the tunnel casting (after
cleaning out the threads. Unfortunately, the undercarriage armor
in the rental service kit interfered, so I had to toss it. The frame
rails provide substantial protection themselves, however.

The rear attachment shows the ROPS bracket connection. Note
the new bolts; these are critical and the original ones were rusty.

 

[mjncad]

That looks to be a nice clean design.

 

[RoyJackson]

Great job, dfkrug!!
I wish I had your skills...and I wish I could still get near a welding machine.

 

[dfkrug]

Thanks, Matt and Roy....I knew I could count on you to read this thread.

Now for the hoe-side of the subframe.

I positioned the hoe at the operational height I want using the two 4x12
wood blocks. I also have my overhead crane supporting the boom for the
correct tilt. I connected up the tractor hydraulics so I could operate the
outriggers for the correct height. I want this to be pretty exact, so I
am not going to count on hydraulics to keep the hoe in position.

After that is all set, I will back the tractor up to exactly the place I want.