Trentay, you bring up good points, and food for thought. But if exact answers exist, I don't know them. For instance, I have never seen the various tractor/loader stress combinations published. They would be easy enough to calculate, but there seems to be little interest. People seem to prefer to trust their instincts. Most just experiment until they find some level that they feel comfortable with.
Full frames for loaders are another matter. Much is known. The need for them in rough service is well documented as are the designs. I tend to do that kind of work on my own machines, but imagine that any Ag fab shop will do it for you if you are concerned about the tractor. Yanmar even published some recommendations on this subject for the last of their models right before they quit selling in this country, so the knowledge is available. When Yanmar was making loaders for their tractors, some came as full frame and some as bell housing only. It all depended on how the tractor was constructed. For example, the YM165D came stock with a full frame loader and the 336D with a bell housing mount. Both being a reflection of how the tractor was built.
The issue of "how much weight is in a bucket" is most interesting. I think I'll start a new thread under that subject and see what we can learn.
