I've noticed that most large mining excavators (PC-3000, etc) can be configured in front shovel or excavator machines. My question is what dictates what type machine a mine would buy?
I'm just gonna take a guess at this, but, I think that the difference would be the digging conditions that the machine is going to work in. If the machine is going to be stripping overburden or working on top of a face then a excavator style front would be the choice. If the machine is going to work the bottom of the face or shot then a front shovel type would be the choice. Like I said this is just my guess but I would say that's the reasoning behind it.
We have a 5230 Cat at our mine, it digs like a shovel. The may we mine an excavator set up wouldnt work, simply because most the time we mine a 50' bench. You can control that face with the shovel set up. Also, tire cuts are the #1 priority with us, we can't be having our trucks backing over rocks.
Simply put: Shovels dug up (sit at the bottom and dig above grade), excavators dig down (sit up top and work in subgrade).
The replies above pretty much sum it up, but I would add that an excavator arrangement is more versatile than a shovel. Shovels are hard to beat at face loading, but struggle at developing new benches, selective digging, working low cuts, and really have a hard time trenching or digging below grade. Excavators can dig below grade, above grade, though slower than a shovel, selectively dig in small areas, scale highwalls, and get drop cuts started. If I had to choose only one to do it all, it would be an excavator, but just for loading trucks out of a high bank, shovels are the tool to use
Look on youtube and type in hitachi 5500 francisco or euclid 260 I think that will get you there. It shows a 5500 shovel sitting on coal loading trucks. I use to drive the hell out of that truck in the video now I work at a different mine. Them euc's beat a cat truck anyday.