You can see the challenge faced by our engineering department. West Grand is capable of receiving up to 15 new loads, but the previous train of 15 empties must be pulled out when the new loads arrive. The design of our dumper and postioner involves the obvious modeling challenges but the the real work is in four mechanical systems. When that's done, we'll add the modeling gingerbread. Most dry product will dump at 135 degrees, but consulting my mining engineer friend, he says they rotate it 180 to insure dumping of wet product.
Barrels seem to fall into three general classes.
One type simple tips the car over the edge of the track, spilling the load into a bin alongside the where loaders can handle it. This take a lot of horsepower and very heavy above ground construction. A second type apparently rotates the car around an axis somewhere near the center of gravity dumping the ore into an underground hopper where a conveyor system hauls it away. This doesn't take much horsepower, and the mechanical stresses are less, but it takes a lot of underground construction. A third type rotates the car around an axis in line with the coupler and provides for quick unloading of a train equipped with rotary couplers without separating the cars.