I had one lock up on an 82 Chevy v6 diesel. That engine had a serpentine belt, which wrapped around the alternator pulley about 270 degrees, putting tremendous pressure on the alternator front bearing. (This POS would eat alternators about every 20k miles). Anyway, it locked up without breaking the belt, which stalled the engine, but I was able to coast into a friends body shop in neutral. When we popped the hood, the alternator was actually on FIRE! For a few minutes, there were 3 guys taking turns spitting on the alternator trying to put the fire out, until a fire extinguisher appeared from somewhere.
2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg
And remember folks, Only You Can Prevent Hilliary.