Diamond Shape Sub-Frame for LW-8 Backhoe

[3RRL]

Hello fellow members.
Boy, it's been a long time since I wrote a new thread.
But I recently acquired a new (used) LW-8 Backhoe from my good friend Scott. It has quite a bit more reach than my Italian made Nardi 220 hoe, so I was very interested in getting it. It also weighs a lot more and has a little more power, which made it even more important to make a super deluxe subframe for the new hoe. Everyone knows how important it is to have a really good subframe to protect the tractor from stress.

Below is a photo of the LW-8 hoe attached to my 55hp Kama.
You can see I have it attached by the 3 point lower drag links and the top link. Even with the stabilizers down on the ground, it moved around quite a bit. I decided to get it into the barn and start figuring out how to make the subframe for it.

 

[3RRL]

What I decided to do was to make a Diamond shaped subframe.
You can see from the (poor) drawing that the new subframe would be super rigid with little or zero flex once it was done. It connects the backhoe subframe parts (welded to the backhoe) to the front loader braces and also to the ROPS, which is rigidly connected to the top of the rear end of the tractor. The front loader support is also rigidly connected underneath the rear end.

The ROPS acts as the center of the Diamond shape, transferring all the stress to the loader frame braces, which in turn supports the engine, bell housing, transfer case, transmission and rear end. Everything will be all tied in together via the frames. In addition on the backhoe frame parts, there will be cross tubes which connect the lower and upper supports, as well as cross tubes running from one side to the other. I figure this would give me maximum rigidity not only up and down, but also for the torsional sideways stress loads.
Below is the concept I used.



And it must be easy to put on and take off.
The plan is to have attachment points on the tractor where I can back the tractor up to the hoe and put on the PTO hydraulic pump. Then drive in more until the bottom supports slide into the mating tractor bottom supports. I will then pin it to the bottom frame (on the tractor) when the hoe is tilted down with the bottom supports level. Then, using the boom and stabilizers, rotate the hoe upwards until I can bolt the top connection onto the ROPS using 3/4"-10 grade 8 bolts. The 1" diameter bottom pins are the pivot point to allow the hoe to rotate upwards once pinned down there.

 

[Ford tractor]

4point mounted hoes usually have a U shaped saddle on the bottom 2 points (that are attached to the tractor by a strong frame) and a round section 2-3" diameter on the lower portion of the hoe. The hoe then lowers itself onto the saddle. There are similar ones on the top and the vertical support is a large screw that provides the tension holding the top on by connecting to the bottom mount. Lot's of triangulation to hold it all steady under the thousands of pounds of digging force.

You may need to worry about the torsional stresses twisting the differential and transmission. Those are known to crack and break on TLB's from swinging a full bucket and from digging to the side.

Should be a fun project.

 

[Hooked_on_HP]

Rob, I have no doubt in your skills and that the finished produce will come out great. But how much weight are you going to add to the already heavier backhoe. Are you going to have to add weight to the front of the tractor to counterbalance the rear.
Bill

 

[3RRL]

4point mounted hoes usually have a U shaped saddle on the bottom 2 points (that are attached to the tractor by a strong frame) and a round section 2-3" diameter on the lower portion of the hoe. The hoe then lowers itself onto the saddle. There are similar ones on the top and the vertical support is a large screw that provides the tension holding the top on by connecting to the bottom mount. Lot's of triangulation to hold it all steady under the thousands of pounds of digging force.

You may need to worry about the torsional stresses twisting the differential and transmission. Those are known to crack and break on TLB's from swinging a full bucket and from digging to the side.

Should be a fun project.

Hi,
You are right about what you wrote.
I've seen the way factory excellent subframes connect like you say. However, I have to engineer in reverse ... kinda. Plus, I tried to make it as simple as possible without having to dis-assemble a lot of the tractor's rear end connections and machining up a bunch of parts to make it like that. Not to mention that I tried to use what little heavy wall tubing I had left without having to buy more steel. Mine came out really good and sturdy considering... The front loader struts plus the manner I connected the subframe side to side help distribute the stress away from the tractor.
Upcoming photos will show what I did.

 

[3RRL]

Rob, I have no doubt in your skills and that the finished produce will come out great. But how much weight are you going to add to the already heavier backhoe. Are you going to have to add weight to the front of the tractor to counterbalance the rear.
Bill

Hi Bill,
Thanks for asking.
I figure the thick wall tubing will add about 150 to 200 pounds (approx). Not enough to worry about IMHO. No weight need on the front since I have a Koyker loader with a 72" bucket and dual bucket grapples on it. My tractor can easily handle the backhoe weight. Plus, it's only on for the time I need it. I never leave it on the tractor, but usually have my custom box blade on it.

 

[3RRL]

To continue, below are photos of the front struts I made.
They are bolted via plates to the FEL tubes in front, and welded to the ROPS inside the cab. That way If I ever have to take the loader off, I can unscrew the bolts and leave the struts connected to the ROPS. (I know I'm going to get heck from the ROPS police, but that's what I did.) I've had that rear bracket with the bolt hole in it on there for 4 years now. I used that one for the previous Nardi backhoe subframe connection. But that one was pinned together there and also on the backhoe, which left room for movement. The LW-8 subframe will be bolted up there with 3/4"-10 grade 8 bolts.

 

[dcyrilc]

Sweeeeet. I'm looking forward to seeing what you've done.

Just this evening, I was thinking it had been a long time since I had seen anything from you and wondering how things were getting along.

 

[3RRL]

In the previous photo, and the second one below, you can see how the Koyker FEL frame has 1/2" thick braces going forward to the motor, and a 2" diameter tube going back to the rear end to take the stress off the motor and transmission and all the bolts holding the tractor together. With that new strut, the loader frame is now supported above and below the rear end making it super sturdy. The ROPS forms the third leg of the triangle for those connections.

The front struts run against the inside of the fenders and miss the accelerator, brake and clutch pedals.
I now have to step over them when entering the cab, so I made and extra set of steps to get in and out of the tractor. Also made 2 sets of steps to get in and out of the backhoe.
Rob-

 

[3RRL]

Hello Cyril,
Nice of you to stop by this thread!

Next was to make the lower backhoe subframe struts.
These would be welded onto the bottom of the backhoe frame. The other end is where they are pinned onto the tractor receiving support frame. I used heavy wall 2" x 4" tubing for the lower frame and 2" x 3" for the upper frame (and those front struts as well). The photos below show the receiving support bars where the backhoe will be connected with 1" diameter pins. They are welded onto the FEL rear support tube plate, and also re-inforced with gussets so they won't budge.

 

[3RRL]

Now that I have the lower receivers reinforced, and the front support tubes installed, I got to making the upper backhoe subframe. They are shown in the first photo below. BTW, all the holes are bored through the thick wall rectangular tubing and then have either DOM tubing (drawn over mandrel) welded in for the holes, or solid steel inserted for reinforcement. The lower receivers on the tractor have solid steel on the inside of the rectangular tubing and the mating ones on the backhoe have DOM. An example of the steel inserted is shown when making the bolt on end of the upper backhoe frames shown in the 2nd photo below. Solid #2 steel (4130) is welded into the rectangular tubing.

The lower backhoe support frame (last photo below) are welded to the bottom of the backhoe. The other end is connected to the receiving supports on the tractor via those 1" diameter pins. Those are the only place where this subframe is pinned.

 

[3RRL]

OK, that's all there is to it.
Below are photos of the backhoe subframe completed. I had to fixture up every connection before and during all the welding to keep a perfect alignment. I had to add some rectangular tubing and plates to both the upper and lower backhoe connections to make them support the hoe properly. Other than that, it came out pretty sweet.



Note also that both upper and lower frames are cross connected vertically and horizontally to each other with 1-1/2" diameter round tubing. This pretty much keeps the whole shebang square under load. When connected up to the tractor, the diamond shape is completed and further bracing throughout the tractor and backhoe is achieved...front to rear.

 

[3RRL]

So here is how the backhoe is connected up to the tractor.
The first photo below shows the upper connection bolted together. It also shows the front strut support going down to the front FEL support. The second photo shows the lower connection pinned together. I took it outside for a tryout after that.



You can't believe how worried I was about line up before I connected it up.
I was very pleased when I backed the tractor up to the backhoe and the lower connections lined up to be pinned together easily. Then I used the backhoe to push itself up, rotating up on the lower connecting pins until the upper bars touched the ROPS (it cannot rotate up any further). I then screwed in the 3/4"-10 bolts and the subframe was 100% connected.

 

[3RRL]

I wanted to share a couple more things.
Before I put the backhoe back together, I machined out the plate covering the valve. There were "+" shaped clearance slots for the control handles in it, making it impossible to control the backhoe with simultaneous movements such as pulling in the dipper stick and curling the bucket at the same time. Or extending the boom and swinging at the same time. Boring out that plate made it act like a regular backhoe. And of course, my dear wife Loretta helped me through the whole project and did all the paint touch up for me, as usual.

 

[3RRL]

There were a couple last things to do before it was ready to dig.
First, I had to secure the PTO pump to keep it from spinning (first photo). Second, because I do not use the lower links, I had to make sure they didn't creep down onto the hydraulic tank which is mounted on the backhoe. I made a bar which holds the lower links in position ... not only up, but spread the right distance apart so they will clear properly when backing the tractor up to the backhoe. I put this on before I connect the PTO pump, and then back in the rest of the way for the hook up.



After that, I took the tractor out and started to dig a 60' long trench for the water and electrical lines for Loretta's garden shed. That's one of the projects we will be working on in the next few months.
Perfect timing...
Rob-

 

[Eagleview]

I wanted to share a couple more things.
Before I put the backhoe back together, I machined out the plate covering the valve. There were "+" shaped clearance slots for the control handles in it, making it impossible to control the backhoe with simultaneous movements such as pulling in the dipper stick and curling the bucket at the same time.

I'd thought you'd gone AWOL Rob .

You have me a little confused here , I take it the controls you have are x+ axis controls and not just + ? They would have 8 or more hydraulic hoses going to them and not 4 ?

Great job on the frame , it's good to see someone who knows that strength is not in weight , but in fabrication .

 

[mjncad]

As usual Rob, you did a great job.

 

[3RRL]

Hi guys and thank you, always good to hear from you guys.
I'm still kicking but have been mostly reading and not posting much.

Iron Horse, there are 14 hoses coming out of that valve for the cylinder controls, including stabilizers and in and out (return to sump). What I was talking about was that the plate covering the backhoe valve was machined (or punched die) with slots (see photos) to allow the control handles to move only forward and back and sideways ... not allowing the handles to go into a 45 degree angle where two functions can operate simultaneously. In other words, the slots only allowed the handle to be pushed straight forward and back, and you had to get out of that slot to move the handle sideways. So the slots only allowed you to move one cylinder at a time, not two.

For example, when moving the dipper stick, you could only move it out and in.
If you wanted to curl the bucket, you had to get out of that slot and move the handle into the sideways slots. Then that allowed you to curl the bucket in and out. By removing the + shaped slots, I can now move the handles at a 45 degree position which allows simultaneous movement of the bucket curl and dipper stick. I know I've been redundant in trying to explain, but I hope I've written that clearly enough so as not to be confusing?

Below are photos of the hoses and valve control handles.
The 2 with slots are for the stabilizers, and the other 2 are to operate the boom, dipper stick and bucket. Those are the ones that now have a circle for simultaneous movement instead of the "+" shaped slots that used to be there as shown in the middle photo below.

 

[3RRL]

However, I did not come up with the idea.
I believe Tim Wales, long time member here, was the first (if I remember correctly) to do that to his backhoe plate. Having said that, and having owned the Nardi backhoe for almost 5 years knowing it should do that, I think I would've attempted it anyway. The valve, however, is not nearly the quality and smoothness of the Italian Nardi backhoe.

I don't know if you noticed or not, but some photos show the huge Kama fronts and rears off the ground in one of the last pictures. This subframe is so rock solid that even the slightest movement of the backhoe is absorbed by the subframe. In other words, there is Zero play in it. And I mean absolutely ZERO play! And once the backhoe is up on it's stabilizer feet, it feels rock solid when digging.

When I push one of the stabilizers down, or the boom down, the entire tractor moves with it.
My other subframe for the Nardi backhoe always allowed the backhoe to move independently of the the tractor for a few inches before that subframe tightened up. That shows (to me) how rigid this new subframe turned out. It not only solidifies the backhoe subframe, but has solidified the FEL subframe as well (through the front struts connection).

So it was a worthwhile investment for me in more than one way.
I'm very confident that there will be no damage to my tractor either from backhoe or FEL use now.

 

[EddieWalker]

Another great project. I like the way you engineer stuff and explain why you do what you do. Nothing is random, and everything has a reason for why it was done that way!!!!

Now that you have the bigger hoe, when does the thread on your pond begin? LMAO

Eddie