Why is AC Voltage applied to the 3 Rail Track while the Locomotive motors are DC Voltage Motors ?
Were the LIONEL Locomotive motors once AC Voltage Motors ?
Gunrunner answered your first question very well. The first Lionel, in fact all the early three rail and two rail motors were not only AC they were AC / DC universal motors. Even these motors run smoother and quieter on DC. Much of the reasons these motors were so common until the sixties is the lack of a suitable low cost material for permanent magnets. Early permanent magnet motors lost their charge just sitting let alone if you used them. The first Alnico alloy was created in Japan around 1930 and took about thirty years to trickle down to consumer products. I suspect WWll played some role in the delay. Even in aircraft where weight is a critical factor the universal AC / DC motor was still used in such applications as trim-tab motors. Gordon Varney one of the fathers of HO in the United States stated that the lack of suitable motors was one of the big hurtles in the early growth of HO scale. The development of the Alnico magnet was key in the development of a dependable HO sized motor. The fact that O scale was large enough to accommodate motors with stator windings delayed the adoption of permanent magnet DC motors in O scale / gauge both for two and three rail. j