Tank & Vat Cars
The earliest version of tank car began to appear in the early 1860s during the American Civil War. Essentially, a standard flatcar was employed with two or three vertical vats placed on top used to transport liquid-type products. Unfortunately, the design had several flaws; the most obvious was that it could not hold much product due to height and width limitations, plus leaking was a constant issue. By the late 1860s, following the war, the first true tank cars began to take shape where railroads began to create a horizontal vat-on-flat-car design, which was then mounted to a traditional flat car. The design was roughly, but became the foundation of the traditional tank car.
As American industries grew in the late 1800's and early 1900's and demand for more efficient transportation of liquid materials were needed, the tank car continued to be refined and eveole until the 1930's. By this time, the traditional looking tank car had been designed. Although it conntinued to be improved for the the next half century, the basic concept was in place by the mid 20th centuury.
Lionel offered several tank car shapes and styles during the postwar era. Availability ranged from single, to double and finally triple dome versions as well as different styles within each version. With the exception of a few brightly colored offerings, the tank car is the most prototypical freight car produced by Lionel. On the other hand, the vat car is based on a seldom used freight car designed to transport pickles. Lionel produced only two versions -- each with the same number, 6475.