Backhoe Strong?

IslandTractor · Sep 13, 2015

RoyJackson said:
Welding cast iron is tough. To do it properly, one needs to disassemble the components of the bell housing (or transmission case, if that's what it is). The casting should be pre-heated to about 1500 degrees and the rod to be used is formulated for cast iron.
My guess is the original welding was done on the tractor and no pre-heat.

More info:
Guidelines for Welding Cast Iron

The Deere 448 backhoes use two plates mounted to the transmission housing and ROPs mounts. Once the 3PH draft links are removed, the 'hoe is lifted with the rockshaft lift links, two pins (each about 1.5" in diameter) are installed through the 'hoe frame and tractor mounted plates. The lower 'hoe frame sets in two slots in the tractor mounted plates. After all that, the lift links are lowered and the backhoe hydraulic hoses are plugged into the tractor's hydraulics.
It's a pretty robust and the stresses seem to be well distributed.
The manual doesn't specify it, but the illustrations indicate the stabilizers are to stabilize, not lift the tractor. I've only used my backhoe once, and that was just to try it out (I didn't buy the tractor for the backhoe...backhoe was just part of the deal) and all four tires were on the ground.

As far as the DK45 (topic of this thread), it's entirely possible the backhoe usage had nothing to do with the casting failure. Castings tend to have other flaws common to the casting process...and these flaws can (and have) lead to cracks.

Roy, I'm sure cast iron does not need to be heated quite as high as 1500F to weld. Indeed, Lincoln points out that heating cast iron above 1400 is a bad idea and recommends 1200 as a max (500 min). Certainly adequate heating is important and even more important is slow cooling but cast can certainly be welded at less than 1500. The key is to prolong the cooling phase. There are a number of welding sites that discuss cast iron repair and relatively thin cast iron (less than 1/2 inch or so) as with a transmission case can be done at temps half that high or even less.

Here is a link to a Lincoln how to article: Repairing Cracks in Cast Iron

RoyJackson · Sep 13, 2015

IslandTractor said:
Roy, I'm sure cast iron does not need to be heated quite as high as 1500F to weld.

I got that 1500 degree pre-heat off another link (which I didn't post). This was dealing with engine blocks which can be pretty thick.

I've never welded cast iron personally, but have seen it done and done successfully. But I've seen more brazed, again, successfully.

One thing I do suspect in the DK45's situation...several CUTs use the engine and transmission case as part of the frame, rather then a separate frame with the engine and tranny mounted to it. This would correspond to a car with a frame and body compared to a unibody.
In the separate frame situation, the frame takes the twisting forces...any castings mounted to it aren't under much (if any) additional stresses. A tractor using the transmission case as part of the frame would see stresses and any weld repairs would be under additional stresses (especially if the casting wasn't stress relieved after welding). Good chance the weld would eventually fail, or the crack propagate further.
This is all supposition (based upon a small degree of knowledge and experience gained over the years) on my part.

chuck172 · Sep 13, 2015

"One thing I do suspect in the DK45's situation...several CUTs use the engine and transmission case as part of the frame, rather then a separate frame with the engine and tranny mounted to it. This would correspond to a car with a frame and body compared to a unibody.
In the separate frame situation, the frame takes the twisting forces...any castings mounted to it aren't under much (if any) additional stresses. A tractor using the transmission case as part of the frame would see stresses and any weld repairs would be under additional stresses (especially if the casting wasn't stress relieved after welding)"

Quoted you there Roy, Think your touching on something. If the Bh subframe were to attach to the loader and Rops frame, that would take lots of stress off the Bellhousing.

hutchman · Sep 13, 2015

IslandTractor said:
Not quite as easy as that. The issue with 4pt mounts is that all 4 contact points need to be lined up at the same time in 3 dimensions. Not terribly easy even after hooking up hydraulics and controlling the pitch and height of the BH with stabilizers and then backing into the BH. You can only control the BH height and pitch while off the tractor and can only back up the tractor while on the tractor. Not always simple. And, with the Woods, you hook the bottom pins into slots but the top pins are actually bolts that pass through the subframe so need to be lined up nearly perfectly in order to pass the bolt through and then attach the castle nut. You cannot just persuade it though the hole with a hammer as you'll strip the threads.

The advantage of the other style is that you can back the tractor over the subframe, use the BH hydraulics to raise the front part of the subframe to the right height (not nearly as fussy as with 4pt) and then back the tractor on to the front mounts and then adjust the rear mount height before backing the tractor to secure the rear mount. Two steps but each step is easy. I never had to stick my head under the tractor either. Yes, you need to judge where the front part of the subframe is as you raise it but you can do that from the side. Once you have the front mounts lined up and in contact, the rear mount just slides in and you use tapered pins to lock it in place. The tapered pins can be whacked with a mallet/hammer to make the final 1/4" adjustment.

I remember mounting the Kioti BH in 5-10 minutes most of the time. The Woods routinely takes me a minimum of 15 and sometimes double that.

I don't know about the Woods type you described (I do have the Woods manual for their 4pt. mount for the TC45 and studied it too) but I watched my friend hook up his Bradco and thought it was super slick which is why I went through all the trouble to figure out how it worked and copy the parts I liked.