Link-ups, or couplings as they are more formally known, are the devices used for "easy" hook-ups between cars. Shown here on the right are drawings showing the progress of Janney's automatic coupler, which became the industry standard because of the ease of use and safety reasons. This coupling was perferred over the dangerous link and pin (next card) because it didn't require a train operator to work it. Today's link is a direct descendent of this one.