Diamond Shape Sub-Frame for LW-8 Backhoe

   / Diamond Shape Sub-Frame for LW-8 Backhoe #1  

3RRL

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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.

 
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   / Diamond Shape Sub-Frame for LW-8 Backhoe
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OP
3RRL

3RRL

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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.
 
   / Diamond Shape Sub-Frame for LW-8 Backhoe #3  

Ford tractor

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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.
 
   / Diamond Shape Sub-Frame for LW-8 Backhoe #4  

Hooked_on_HP

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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
 
   / Diamond Shape Sub-Frame for LW-8 Backhoe
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3RRL

3RRL

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Foothills of the Giant Sequoia's, California
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55HP 4WD KAMA 554 and 4 x 4 Jinma 284
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.
 
   / Diamond Shape Sub-Frame for LW-8 Backhoe
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3RRL

3RRL

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55HP 4WD KAMA 554 and 4 x 4 Jinma 284
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.
 
   / Diamond Shape Sub-Frame for LW-8 Backhoe
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3RRL

3RRL

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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.

 
   / Diamond Shape Sub-Frame for LW-8 Backhoe #8  

dcyrilc

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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.
 
   / Diamond Shape Sub-Frame for LW-8 Backhoe
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3RRL

3RRL

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55HP 4WD KAMA 554 and 4 x 4 Jinma 284
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-

 
   / Diamond Shape Sub-Frame for LW-8 Backhoe
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3RRL

3RRL

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55HP 4WD KAMA 554 and 4 x 4 Jinma 284
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.

 
 
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