dead manβs switch
n.β Β«A safety switch was disconnected in a runaway locomotive which crushed three people to death in Milton on March 14, an inquest was told yesterday. The switch, called a dead manβs switch, first gives a warning whistle and then stops a moving train engine if the operator does not have his foot on the switch pedal.
Β» ββSafety switch not on when train killed 3, Milton inquest told” by Zuhair Kashmeri Globe and Mail (Toronto, Canada) June 29, 1978. (source: Double-Tongued Dictionary)