a motorvehicle safety cut - out switch spring biased in a closed position to cut out the vehicle motor is contained in a housing which includes retaining means for receiving a spherical body through a flaired and resilient opening , and includes means for opening the switch in response to the presence of the spherical body in the retaining means . a lanyard connected to the spherical body is attached to a motorvehicle rider to yank the spherical body out and cut off the vehicle motor if the rider falls off the vehicle .