Abstract: A transfer apparatus includes a shuttle depending from an overhead support with a pair of arms for receiving and shifting a specimen carrier from one conveyor to a second conveyor of a dual-conveyor track. The shuttle is operable to retain a specimen carrier along either the first or second conveyor and to release a specimen carrier along either the first or second conveyor. Sensors are located to detect the presence of a specimen carrier at each of the retention locations, and to confirm the release of a specimen carrier from the shuttle along each of the conveyors. A drive motor for moving the shuttle between the retention and release positions is electrically connected to a command module with a processor, for receiving instructions as to the position of the shuttle. The sensors are also connected to the processor to transmit detection data to the processor. A queue is positioned upstream of the shuttle and is electrically connected to the processor.