Abstract: A sensor device for detecting whether a tractor and a trailer of a truck are connected includes a container having a plurality of tabs extending radially outwardly to engage an inside surface of a bearing plate of the trailer when the container is located in a hole in the bearing plate. A spring extends from a base of the container away from the face surface to bear upon an interior wall of the trailer to bias the tabs into contact with the inside wall when the container is located in the hole to maintain a position of the container therein. A sensor is also provided for sensing proximity of a ferrous material and being located in the container. The sensor senses proximity of ferrous material of a coupler carried by the tractor without sensing ferrous material of the bearing plate.

Abstract: A method and apparatus for determining whether cargo is present in a freight car. The freight car has a proximal (“rear”) end with a loading door and opposing, distal (“front”) end. One or more transmitters and receivers are mounted inside the freight car at the front end, toward the car's ceiling. The transmitters/receivers are operated by a controller, which also functions to analyze data from the transmitters/receivers and transmit related reports to a remote monitoring site. During a prescribed time period, a transmitter generates an ultrasonic signal pattern with a coverage area of prescribed radius that terminates before reaching the loading door. During the time period of transmission, or slightly later to account for signal reflection time, the controller operates the receiver to detect reflected signals originating from the transmitter.