Automatic Couplings make all connections between the rail vehicles without human intervention, in contrast to autocouplers, which handle the mechanical aspects. Automatic couplings are recommended for use with advanced precision fluid systems for space flight, aircraft, ground and undersea applications. The automatic couplings are used to join double-carriage units when trains require four or six carriages. The automatic coupling system includes a means for detecting a coupling contact and for controlling locomotive systems such as throttle & brakes.