Novel Door Lock Stops Gangsters (Jul, 1934)
Novel Door Lock Stops Gangsters
AN AUTOMATIC electric clock built for revolving doors such as are used in banks and department stores was designed by three Minneapolis inventors to thwart gangster attempts at wholesale robbery.
The device is concealed in the wall just above the axis of the door. In case of a holdup any employee can press the alarm push button. A small electric motor immediately engages notched clutches which prevent the door from turning.