centrifugal brake
n (General Engineering) a safety mechanism on a hoist, crane, etc, that consists of revolving brake shoes that are driven outwards by centrifugal force into contact with a fixed brake drum when the rope drum revolves at excessive speed
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014