When Arnold began to manufacture its line of model trains, it could not have known how much of an influence it would be in the model railroad industry. The early Arnold rapido 200 product line used a crude piece of bent metal to couple the cars together. It would be the evolution of their coupler design that would be such a great influence.

Couplers are the sort of thing that are in the background yet their design is everything.  The early bent metal coupler did what it was supposed to do, hold the cars together, but the genius of loose car railroading is that cars can be uncoupled from each other, exchanged with other cars on other railroads. This dynamic property allows for our modern world, with freight cars able to cross a continent handled by multiple trains on multiple railroads.  The coupler is everything.

Arnold would go to another German firm for its design.

The first sentence of this description on page 2 of the 1965-66 catalog and also on page 4 of the 1966-67 catalog says it all. The Arnold rapido coupler design was a Rokal licensed item and there begins an interesting tale. Before N-Scale, there had been TT-Gauge, the earlier step toward smaller model railroads. In the period immediately after the Second World War, two companies had begun the movement toward trains smaller than H0.  The American company, H. P. Products, would use a modified Baker type coupler. Rokal, the German company, would design its own coupler.

Rokal couplers

The Rokal coupler worked reasonably well and it was inexpensive to manufacture. But while the Rokal coupler worked well with a track mounted uncoupler, uncoupling the cars manually required a deft hand and a degree of patience.  Some designer at Rokal had studied the problem and had come up with a solution design that worked better and uncoupled by hand much more easily than their current design.  But at this point (circa 1961), Rokal had been manufacturing trains for over fourteen years, with a lot of product already in place in homes across the world. A change of couplers was unthinkable.  And, so this coupler design would come to K. Arnold of Nürnberg.

There was an interim design, meant to couple the earlier metal claw hook couplers to the new coupler. Note the vertical bars on the coupler at each end of the locomotive below; these bars allowed operation with the earlier claw coupler equipped cars.

In the interim period of manufacture (ca. 1961 - 1963), a notice was included with rolling stock advising model railroaders of the purpose of the vertical bar; they were advised that this bar could be removed if it was not necessary.

Eventually, by 1964, Arnold rapido equipment came equipped with the coupler that we now know as the “Rapido Coupler”.  At the same time, Minitrix was using a “Baker” type coupler. 

But what happened next is crucial to the development of the entire N-Scale sector of the model railroad hobby.  For reasons unknown, Arnold allowed other model train manufacturers to use their coupler design.  Although some texts point out that the other manufacturers made minor changes to the basic design so that they would not infringe upon Arnold’s design, other texts and individuals who have studied the history of N-Scale indicate that Arnold willingly shared its design.

In any case, reference to the “Rokal License” ended with the 1966-67 catalog; at the same time, Rokal itself was going into bankruptcy and would shortly disappear from the railroad manufacturing scene.

Regardless, the Arnold rapido design was inexpensive to manufacture and reliable in operation, all other model train manufacturers quickly took up the Rapido coupler, which, in turn, allowed for the very quick growth of the N-Scale sector of the model railroad hobby.

In time, other more realistic designs took the place of the Rapido coupler, but one has to wonder what would have happened to N-Scale if the coupler design had not been given away by Arnold.