Hans is right. The infinite switches were controlled by a clockwork mechanism to cycle the heat on and off. One of my aunts who lived in Milwaukee had a Thermador freestanding range. The heats, after HI were 90, 80, and so on down to LO, but they were infinite and were based on percentages from 100% at High. It was from the age when ovens used concealed bake elements and the reason she was forced to get rid of it was because the floor of the oven rusted out. Otherwise, it was a very heavily built range and, at the time, they were made in Milwaukee. According to the 1960 Official Home Appliance Trade In Blue Book, L&H changed their name to Thermador in 1954. In 1947, L&H offered an electric and oil combination range. In 1949 and 1950, the company gave names to some of the models, beginning, in 1949, with the Norton Standard, Ardmore Standard, Sheridan Deluxe, & Deluxe. There was an oil/electric combo and a wood/electric, a model with a divided cooktop, 4 units on the left, two ovens with 4 surface units and two ovens with 6 units. In 1950, there were 3 & 4 unit apartment ranges, the Norton Standard, the Carleton, the Shelburn wood, coal or oil combos, the Coronet with 4 units and two ovens, the Sheridan Deluxe and the Supreme Deluxe with two ovens and 4 surface units. Through 1958, Thermador continued to offer a range with 6 surface units. The front location of the deep well was a boon for shorter cooks. The model illustrated probably has a warming oven located under the deep well side of the range.