Slip coach
RAIL PASSENGER CAR DETACHED FROM TRAIN WHILE STILL MOVING AT SPEED
Slip carriage; Slip-coach; Slipcoach; Slip coaches
A slip coach, slip carriage or slip portion in Britain and Ireland, also known as a flying switch in North America, is one or more carriages designed to be uncoupled from the rear of a moving train. The detached portion continued under its own momentum following the main train until slowed by its own guard using the brakes, bringing the slip to a stop, usually at the next station.