Interesting video of coal and ore handling in South Philadelphia. Video looks to be from the '90s. I've seen hump yard classification, but I've never seen such steep ramps as in this video. Also that thing (steam, hydraulic, is there a chain under there?) that pushes the cars up the ramp is impressive. That must take a hell of a lot of force. At the bottom of the ramp it's quite a difference in the position of the truck relative to the car's frame; I wouldn't have imagined that the main pin would permit (tolerate without breaking :) ) such free movement.