Abstract: An electromechanical device for transmitting a binary ON-OFF or an analog signal through a rotary connection between two parts of a mechanical system. It is applicable to rotary connections in general but particularly as a warning system for work platforms which employ swivelable casters having operator actuated locks to prevent movement of the platform during work operations. The swivelable caster includes a lock or brake and means for engaging and disengaging the lock. The caster includes a hollow shaft which allows pivoting of the caster The shaft is journaled in the platform base and includes an axially extending actuator operated by the lock or brake actuator to operate an electrical switch carried by a work platform and mounted near the caster shaft for operation whenever the caster brake is engaged regardless of the swivel orientation. Discrete ball bearings are trapped in the hollow shaft and displaced by a wire cable moving between the trapped balls.