Initially patented on June 24, 1974, under United States Patent Number 3788237, the basic Schnabel Car design calls for a pair of multi-truck, multi-axle railway cars, with arms that extend over one side of each unit and jack mechanisms for raising and lowering a load that is positioned between them.
Once it has been attached to the set of individual end cars, the cargo then becomes an integral part of a single piece of rolling-stock.
Should a load not have integrated lift rings, a longitudinal support platform can be mounted between the car ends and the cargo is then secured to this skid.
As is the case with large, depressed center flatcars and the military railway artillery guns that were used in both World Wars, with or without the use of additional pairs of trucks/boogies, weight distribution across the rails is accomplished through the use of numerous axles.
In order to compensate for railway irregularities and/or to reposition a load to clear trackside obstructions such as highway crossing signals, railroad signals, and switch stands, while the arms are in a transit position, hydraulically operated jacks can be used to moderately shift the position of an attached load.
Once the cargo has been delivered, the now separated vehicles can be connected together and returned to their point of origin.
Run in dedicated train consists that are often comprised of idler cars, passenger or crew cars, and tool cars, Schnabel cars do not traverse the railways alone.
Manufactured by Krupp, for Combustion Engineering Inc., in 1982, with an empty car length of 231.667 feet, the world's second largest Schnabel Car (which is North American based) is Westinghouse's WECX 800 (formerly CEBX 800), which has a maximum loaded length of 345.00 feet, an empty weight of 370.45 tons, and an 889.63 ton weight load limit that is distributed across thirty-six axles that are fitted with 33 inch wheels.
Ironically, Krupp is the same firm that created the world's best known railway artillery gun, the K5, which was used by the German Wehrmacht (Defense Force) in World War II.
Built by New Castle, Pennsylvania based Kasgro Railcar in 2012, presently, the world's largest railcar (i.e., Schnabel or otherwise) is Westinghouse's WECX 801, which was derived from replicated drawings of its sister car, WECX 800 (ex CEBX 800).
With an empty weight of 399.60 tons and a weight load limit of 1017.90 tons that is distributed across thirty-six axles that are fitted with 38 inch wheels, to date, WECX 801 is the biggest car that has ever been constructed in North America.