dead man's handle

dead man's handle (plural dead man's handles)

1. A lever used as a safety device, typically on trains, which shuts off power if the operator releases their grip.
   • 2012, Andrew Martin, Underground Overground: A passenger's history of the Tube, Profile Books, →ISBN, pages 103-104:

     There were two engine men in case one of them fainted or died, the 'dead man's handle' of the later Tubes (a fail-safe device that stops the train if the driver does not maintain manual pressure on a lever) not having been perfected.

• “dead man's handle” in the Collins English Dictionary
• “dead man's handle” in Lexico, Dictionary.com; Oxford University Press.