In the postwar period, smaller model train sizes became the order of the day. In earlier times, model trains had been largely the plaything of the well to do who had enough money to live in houses large enough to support the display of the larger scales of model trains. The growth toward smaller scales had begun in the early 1900s, with O scale being the first 'small' scale. In the 1930s, HO / OO scale became the 'small' scale. In the late 1940s and 1950s, TT scale was the 'small' scale, allowing for realistic model railroad displays being situated in relatively small areas. Three companies led the TT revolution, H.P. Products of Indiana, USA, Triang of Great Britain and Rokal of West Germany.
But TT-Scale was not to be the smallest scale in model railroading. Led initially by Lone Star Toys of Great Britain and Trix of Nürnberg, there was a movement toward an even smaller scale. Both companies experimented earlier with floor toys, unpowered model trains designed to be moved about by child power. Lone Star dropped by the wayside after a period of time, but Trix continued experimentation and development of what would be their electric powered Minitrix product line. Arnold was to come up with a workable solution, also. The introduction of Arnold rapido was from scratch because nothing like this had been done before. There was some precedent for this smaller scale, with other manufacturers such as Minitrix and Lima also thinking about using this proportion. Arnold is usually acknowledged as the company that started what would become N-Scale. In the early 1960's another company, Lone Star of England, also began production of a product called 000-Gauge. The Lone Star model train line disappeared sometime in the early 1970's.
There are several distinct phases of Arnold's model train production. In the period of 1960 - 1962, Arnold marketed the Arnold Rapido 200 product line; this line was very crude yet it also was a sensation because of its much smaller size than TT.
The next phase was from 1963 - 1967, when the rapido product line begins to swing toward scale representations of the trains. It is during this period that the "Rapido Coupler" comes into production, beginning its widespread use by all model train manufacturers in N-Scale. It was in 1964 that the term "N-Scale" came into use. Between 1968 and 1970, rapido line of trains reached maturity, notably with its turntable and roundhouse. Arnold entered into a business relationship with the U.S. company Revell around 1968, beginning the marketing of Revell Rapido model trains. This relationship was marked by the beginning of production of North America more accurate North American prototype models by Arnold. This relationship continued for several years, ending in the late 1960s or early 1970s. Arnold continued their expanded production, with new models until the early 1990s.
Source and more info: Wikipedia
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