Freight trains travel usually on a 4x2x4 basis in the mountains... Meaning, you have 4 locomotives up front, 2 in the middle of the car-load, and 4 in the rear. The middle motor is called the "swings." Such trains are not allowed in the yard, so you have to take them out of the equation, or in railroad terms, "Cut the swings" for short. This song was composed in my head while waiting for dispatch to authorize the movement.