I bumped into this train while passing through the Lake Shasta, California, area. Pretty cool all-wheel-drive system.
I'm not totally sure why it would need this, perhaps it needed the extra traction to push the huge wooden railroad snow plow which was nearby. Or maybe it needed the extra traction to haul heavy loads up the steep grades in the area. Either way it must have needed daily grease gun work and I'm sure it had a ton of parasitic loss.