dead man's handle

dead man's handle

or

dead man's pedal

n

(Mechanical Engineering) a safety switch on a piece of machinery, such as a train, that allows operation only while depressed by the operator

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014