Radio-controlled machine power cut-off

摘要

A pair of battery-powered radio transmitters are individually worn on the wrists of a machine operator, and two radio receivers are tuned to receive the signals broadcast by the radio transmitters, the first radio receiver being a proximity-sensitive device switching off the driving power to the machine whenever either radio transmitter comes within a preselected safe distance limit from the work-accomplishing region of the machine whereas the second radio receiver is a radio transmitter operating state-verifying device switching off the driving power to the machine whenever either or both of the radio transmitters fails to transmit its characteristic broadcast signal.