That's for side loading high wall trailers without a long boom. Looks like it was a grapple as well. Common a while back with cardboard/ paper recycling
I've seen it used to load wood chips as well.
I believe they call them high tip buckets.
I see wood chip loaders. I'm amazed the level of wear to the inside of a bucket. operators never lay the floor of the bucket on concrete, so bottom side wear is limited to the replaceable cutting edge. Inside wear is not what I'd expect. This product is debarked, removing 99% of the dirt, then hammered to snot. Biggest pieces are 4" long, 3/4" across. This example has diamonds added to the outer inside, likely either AR500 or high manganese anti wear & they are heavily worn. Also has hard wear protectors facing the raised spaces where the loader pins in. Cutting edge bolts somewhat protect other areas. Last 6" of the cutting edge is separate from the rest of the cutting edge. This bucket takes a loose, (not sticky) material from concrete. I'd bet this loader operates 6000 hours a year.
Thats a pecan sorter
The bucket may have been used in loose dirt which would account for wear on the inside. I've seen those buckets referred to as roll out buckets. They have a higher dump height than a standard bucket because of where the bucket pivots.
They're called a "high lift bucket" or "high dump bucket" in my neck of the woods, they enable the loader to load trailers or bins with high sides, that they can't load with a standard bucket. Here's another version of the idea, a locally built design. This one's for a Cat 938K and it's 4.0 cu. m. capacity with a quick hitch. Buckets - QMW Industries www.qmw.com.au
We used them in the dairy buissness for back hauling manure in a live floor the biggest negative it that they are high capacity and they are very heavy empty I know of 2 trailers that got wiped out saving the loader from tipping over in a corral
Most mills keep the bucket when they buy new loaders. That bucket could be 30 years old. I know the buckets used on loaders at the peat moss fields are polished like chrome from the peat. The OSB mill here put a ramp in and stopped using the high tip bucket for chip trailers.
A buddy of mine has one on a skid for loading snow and if not carful can dump it over the other side of the trailer