
The 9 V system ran from 1991 to 2006 and is still a favourite with LEGO train fans. The rails have metal tops that carry the current from a speed regulator to a motor under the locomotive, so trains could run without batteries for as long as they stayed on the track. It started with 4558 Metroliner in 1991.
2006 LEGO Sets
2006 was a year of creative resurgence, adding major themes while closing older ones. LEGO Batman debuted as the first full DC Comics collaboration, joined by Avatar: The Last Airbender, Exo-Force, and SpongeBob SquarePants. LEGO Mindstorms NXT modernized the robotics platform with sensors and wireless control, and Remote Control Trains replaced the 9V system. Vikings and Clikits ended, while standout collector sets such as the Technic Tow Truck (8285) and Boeing 787 Dreamliner (10177) strengthened LEGO’s appeal among adult fans.