On the -2 series, I know the high voltage gear, such as reverser have electric motors, which move the contractors. One thing I've noticed, even on the new Eco rebuilds, is escaping air sound, when coming out of dynamic brake. What does the air control?
"Welcome all ye who enter; the show that never ends. Tingfield Sperminal Railway." (Graffiti on the entry to Mohawk Yard Office)