Mechanical focus: couplers

Couplers need to be the strongest link in a train, capable of withstanding extreme forces of buff (compression) and draft (expansion). Since the semi-automatic “Janney” knuckle coupler was patented in 1873 and mandated by the 1893 Safety Appliance Act, couplers, and the standards that govern them, have undergone numerous improvements and adaptations for varied types of car designs and service applications, all of which are under the auspices of the Association of American Railroads.