Ｆ７等のディーゼル機関車のヘッドライトは2灯式になっているものもあり、１灯は赤くなるようになっています。グレートノーザン鉄道では、旅客用Ｆ７は２灯式となっています（貨物用は1灯のものが多い）。
その運用方法ですが、gngoatでの議論によりますと、緊急ブレーキをかけたときに自動的に赤に変わるということです。また、後進時にも赤色灯をつけるということです。
参考までに原文を転載します。
The Mars lights on both the locomotives and trains was manufactured by the Mars Signal Light Company of Chicago. What I found on the web it is not related to the candy company.
I spent about ten years as a volunteer at the Illinois Railway Museum and some of that time was around the Burlington E5 that still has a fully functional Mars Signal light. The red would automatically turn on and the lower twin sealed beam and the upper clear light on the Mars light would turn off when the train went into emergency brake. What I think happened once trainline air had been restored was the red turned off and the clear lights would turn back on.
Now the Mars light itself was under control of the engineer just like the lower twin sealed beam. The engineer could turn the Mars off completely when the train was not in emergency or turn the Mars on and the upper bulb which was clear would ocilate. The lower bulb was red on the Mars. The engineer could also turn the RED Mars on when he was making a backing move and all the clear headlights off so that now the locomotive was acting like a Mars equipped tailcar.
その運用方法ですが、gngoatでの議論によりますと、緊急ブレーキをかけたときに自動的に赤に変わるということです。また、後進時にも赤色灯をつけるということです。
参考までに原文を転載します。
The Mars lights on both the locomotives and trains was manufactured by the Mars Signal Light Company of Chicago. What I found on the web it is not related to the candy company.
I spent about ten years as a volunteer at the Illinois Railway Museum and some of that time was around the Burlington E5 that still has a fully functional Mars Signal light. The red would automatically turn on and the lower twin sealed beam and the upper clear light on the Mars light would turn off when the train went into emergency brake. What I think happened once trainline air had been restored was the red turned off and the clear lights would turn back on.
Now the Mars light itself was under control of the engineer just like the lower twin sealed beam. The engineer could turn the Mars off completely when the train was not in emergency or turn the Mars on and the upper bulb which was clear would ocilate. The lower bulb was red on the Mars. The engineer could also turn the RED Mars on when he was making a backing move and all the clear headlights off so that now the locomotive was acting like a Mars equipped tailcar.