Retarder (railroad)
Device used to slow railroad cars in classification yards
From Wikipedia, the free encyclopedia
In rail transport, a retarder is a device installed in a classification yard used to reduce the speed of freight cars as they are sorted into trains.


Construction
Computer control
Modern retarders are computer controlled to apply a precise amount of pressure on the wheels so that cars rolling down a yard's hump are slowed to a safe speed for coupling with cars already standing on the yard's tracks.[2]
Inert retarder
An inert retarder holds a cut of classified railcars to keep them from rolling out of a yard.[3]