In 1972 LEGO released the 4.5V and 12V train sets as part of the Blue Era which was named because of the rail color. These train sets used additional conductor rails mounted between the standard 4.5V rails and 12V motors contained in the same housings as the 4.5V motors, but with additional metal contacts attached to the bottom of the housings.
1986 LEGO Sets
In 1986, Castle advanced with the Black Falcon’s Fortress and new armor elements, while Town and Space received steady expansions. Technic deepened its engineering focus with more gears, linkages, and pneumatics, and began limited experiments with computer-assisted control in educational contexts—precursors to later robotics lines.