Sistema 3N de IBERTREN

Hello friends, in this video I'm going to tell you about the IBERTREN 3N system. Perhaps some of you have heard of it but don't know the characteristics of this system that IBERTREN introduced back in the 1970s. As an example of a 3N scale model, I'm going to show you the Alco 2100 locomotive. A legendary RENFE locomotive and one of the first models that IBERTREN released in this scale. As you know, for a DC motor to work, it needs two poles: positive and negative. Until IBERTREN came along with this innovative system, all N scale locomotives received each pole through one wheel on the axle. IBERTREN wanted to innovate with this system, where one pole of the current is introduced into the locomotive through the two wheels on the same axle, so the wheels on the axle have to be short-circuited, and the other pole is introduced through the contact shoe located between the wheels. Hence the name 3N. The "three" refers to the three current collection points, and the "N" to the scale in which the models were manufactured. All 3N locomotives are easily identified by this contact shoe in the middle of one of their bogies. This system required the use of track that was unique to IBERTREN for 3N scale. Beneath the track, there is a metal plate, cut so that a tab protrudes from each sleeper. It is on this protruding tab that the contact shoe makes contact to draw current from one of the poles. The other pole was taken from the two rails. If we open the locomotive, we can see the position of the contact shoe and how current is obtained through the contacts on the wheels. This system did not yield good results. Firstly, all IBERTREN locomotives of this period used one bogie exclusively for current collection and the other bogie solely for traction. Unlike the N scale locomotives manufactured in Europe around the same time, where power and traction were supplied via both bogies. And if we add to this the fact that over time the contact shoe becomes covered with a thin layer of rust, which prevents proper power supply to the center rails of the track, these locomotives run very unevenly on the model railway, stalling while running, especially at slow speeds. They also have this problem when passing through turnouts. This can be mitigated if the wheels and contact shoe are clean and the gears are well lubricated, as well as if the 3N track is clean. This power supply system was abandoned after a few years, with IBERTREN producing the same models but this time supplying power only through the wheels and eliminating the contact shoe, like the rest of the N scale locomotives manufactured worldwide. However, they retain the same design of one bogie for power supply and another for traction. This also led to problems with running the trains. This system is now only used by collectors of the IBERTREN brand, who even after more than 40 years continue to run their models on 3N track layouts. Despite the running problems, this system served as a starting point for many model railroad enthusiasts in Spain.