4025 broken bh subframe

[tkevan]

My only comment again is the reason the frame broke is: the load exceeded the design strength . That you have to agree, the reason that happened load was transferred because of a reason. Still go back and check all the bolts attaching the mounts to the tractor if non are loose- the failure was from operating in overload.
No BS just practical science. I am not saying the design is wrong just the load exceeded the design.

Bradco has put a butt-ton (yes, that's an Official Term) of 509 hoes out over the last few decades. It's a proven design.

 

[tracydj]

Bradco has put a butt-ton (yes, that's an Official Term) of 509 hoes out over the last few decades. It's a proven design.

 

[bindian]

I have over 1200 hours on my 6520 and lots of that time was using my Bradco/Mahindra 511 (same hoe and subframe as 509 but with longer cylinders ) backhoe. If I just put a little weight on the outriggers, the hoe can pull the tractor. I put the whole weight of the rear of the tractor on the outriggers to keep from sliding. Lots of times I need to raise a wheel to make it all level. Both wheels are raised to walk it. I can't see tire bulge while hoeing, it is all by feel and seat of the pants experience

Of course my subframe is an inch thick with the added "J" collar at the mount for over 1.5 inches of bearing surface (per side) for the backhoe to sit on. Walking a backhoe puts stress on the upper mount. Continually digging against unmovable roots puts stress on the lower mounts.

The OP's lower mount is the same design as my lower subframe mount is. I think it was just a bad weld that concentrated the stress at the cracked place. I have found the more surface area you have on the ground while digging is better, with all the weight you can manage on the stabilizers. Just dig with your loader bucket raised to see the difference.

In the attached photo you can see how the lower mount just rests on the subframe and how much extra "meat" is below the mount on my subframe. I don't think it has that much metal below the op's cracked subframe.
hugs, Brandi

 

[Navvet]

Not sure how this happened, but the subframe has sheared in 2 places just above the lower mounts. Is this frame cast iron? Is this reparable, or am i looking at a new subframe. Tractor has 70 hrs on it, and very little backhoe use.

I am sure about how that happened ..... It just happened to me, same tractor, same BH, same break ....

1 or more of the bolts on the top back mounting plate for the subframe loosened .... This allowed inordinate stresses on the subframe where the BH mounts.

Hopefully I can get the subframe welded this week.


On a lighter note, I noticed a strange creaking / popping noise so I started to take the tractor back to the shop ....

After roughly 50 ft down the road, the backhoe just fell off my tractor onto the road ....

the looks on the faces on the two guys I was working with ---- priceless ....

 

[DavesTractor]

bmohr1954 is probably correct, the bolts up higher were likely loose. Has the original poster commented on whether the bolts were loose? With all the banter about bulges in tires and outriggers vs stabilizers I may have missed it.

That is a pretty easy welding project. I'd not pay $2000 for mounts if they can be welded up in a couple of hours. Then I'd look at the failure area and see if there is something to do to prevent a repeat. Obviously torque and locktite the bolts that came loose, but perhaps there are other means of reinforcing this area. This is not a hard repair for a competent welder.

Not to dive into the tire bulge debate, but no doubt the compact or farm tractor with a backhoe attachment is far less robust than a dedicated construction backhoe. But they aren't pushing $100k to buy a nice new one either, and you can remove the backhoe in minutes and mow your field. I own a nice track hoe, and it is smooth and powerful, but I bet to replace my pilot controls, just the controls, would cost as much as a new backhoe attachment in it's entirety. We can't expect them to be the same. They are a different animal. We sell over 100 backhoe attachments per year. People are tired of shovels, they need to dig some trenches, perhaps a footing, remove a few trees and so forth. These work great. But if you are digging septics every day or think you want to dig a basement, you need to rent or buy a construction grade machine.

Not to offend anyone at Mahindra, but I think I'd be slow to accuse an operator of abuse based on the premise that if it broke it did so because it was overloaded. What if the area was brittle due to improper welding processes? Tie goes to the runner in my book, but I don't know the details of this claim at all. And if the bolts were loose, how long did that take? If there were loose within a few hours of backhoe use, were they ever tight? Were they checked by the dealer in his PDI? Did they have locktite if the specs required that? I understand a customer needs to keep an eye on his machine, watch out for loose lug bolts, loader bolts, backhoe bolts and such, but they also need to be designed and installed in a manner that keeps them tight for long periods of time.

The good news is, as stated already, this is a piece of cake to fix.

 

[bindian]

Not long after I had been using my backhoe, 3 bolts holding the subframe to the axle housing sheared. I had to drop the right subframe from the tractor and drill and easyout the bolts. They came out easy. New bolts and no problems since. So, when you get a new backhoe, and even a new tractor with loader.............check the torque on all bolts. The dealer installed my backhoe.
hugs, Brandi

 

[erkme73]

No dog in this hunt, but the term "stabilizer" rung a bell for me. I have a 43' diesel-push motorhome that has 'stabilizers'. I've always used the terms stabilizers and levelers interchangeably. But, as it turns out, the former is NOT designed to lift the wheels off the ground, where the latter is. I'm guessing the same logic applies to stabilizers vs. outriggers.

 

[dfkrug]

We sell over 100 backhoe attachments per year.

Wow, that's a lot of hoes, Dave. I will bet that 99% of them don't even get 100 hours on them
in their lifetime.

I probably have 200 hours on my Woods clone hoe, and I just broke the swing cylinder mounts
the other day. Just too many hours of using the swing to move dirt sideways.

Once again, to your point, these attachments are not in the same league as those on industrial
hoes or excavators. Even Bradcos, which are well-made.

 

[DavesTractor]

Wow, that's a lot of hoes, Dave. I will bet that 99% of them don't even get 100 hours on them
in their lifetime.

I probably have 200 hours on my Woods clone hoe, and I just broke the swing cylinder mounts
the other day. Just too many hours of using the swing to move dirt sideways.

Once again, to your point, these attachments are not in the same league as those on industrial
hoes or excavators. Even Bradcos, which are well-made.

We seem to be a hot spot for backhoes for some reason. About half the tractors we sell go out with backhoes. And you are correct, most small backhoes see less than 200 hours of actual digging time in their lifetime. We do see some folks that have a big project in mind when they purchase, and they might run up 100 hours pretty quickly, but that is rare.

Backfilling with the side of the bucket does put a bit of strain on things. Woods builds a nice aftermarket backhoe, but I think Bradco is my favorite backhoe attachment. They are more expensive.

 

[dfkrug]

Backfilling with the side of the bucket does put a bit of strain on things.

Sideways force with CUT hoe attachments is pretty weak due to the geometry, but you still need to use it, and
the hoe should take it. My own hoe uses sleeve bearing inserts for most of the pivots, and that is a good
thing. I have replaced some already and have more on order.

All hoes should have these. Does Bradco?