GS-4 Mars and headlight?

Model Railroader Prototype information for the modeler
1

Hi,

I’ve just programmed my Kato GS-4 so that the Mars light and the headlight can be switched individually, with the Mars light on in both directions and the headlight on in forward only. I was wondering if this is how the lights on the real one were configured?

Thanks in advance,

tbdanny

2

There should be a few switches in the cab. None would be directional, have to turn them as needed.

One for the headlight, off-dim-bright.

At least one for the Mars light, off-on, and stop-moving-bump. Not sure how the SP did things, but usually the moving light needs to be moving when passing over grade crossings, but can be stationary between crossings. Easier to see ahead in the dark if the light isn’t moving around. The “bump” would move the light a bit to line it up straight.

3

The bump feature could and was used to position the mars light forward to use in case the bulb burned out in the regular headlight, which does happen now and then. When used as a mars light, the Southern Pacific normally turned it on and it continued to move while the engine was running.

CZ

4

I’ll just add that on the real thing, both the headlight and Mars light are completely non-directional. They’re on if the engineer turns them on, without regard to the direction the engine is moving. There’s a backup light in the rear of the tender, too, and the same thing is true of that. Lights that automatically reverse direction with the engine are strictly a model railroad phenomenon!

So long,

Andy

5

Also per Rule 17 the lights would be dimmed or extinguished when stopped on a siding for a meet, or at a station etc. where another train could pass it going the opposite direction. At night time I would expect the Mars light would be turned off and the regular headlight dimmed (or turned off).

6

Thank you all for your replies. I think I’ll leave it as it is - I sorta use the headlights on my models as indicators for direction/power at a glance. But I do appreciate the knowledge.

7

On most decoders you can do sort of a ‘hybrid’ version of directional lighting that I like, where both headlights (say on a diesel road switcher) are always on when you hit F0, but the headlight in the direction of travel is on bright and the reverse headlight is dimmed. That way the headlights are always on, but you can still use the headlights to see which direction a stopped engine is set to go.

I’ve also set up a two-headlight F-unit so the lower headlight is on all the time, but the upper Mars light only comes on when the engine is set to go forward. Just my opinion, but to me that seems more realistic than having the Mars light on all the time, and the lower headlight going on and off with direction of travel.

8

I wish I could do that - being in N scale, my F-units don’t have space for more than one LED in them.

9

I believe it was always Southern pacifics standard practice to use both the main headlight and the Mars headlight.I have seen many vintage videos and don’t remember ever seeing the GS-4’s with out both headlights on.There really would be no reason not to have them both on as it made the locomotive easier to see from far away.

On SP diesels…

Growing up in Denver where the D.R.G.W. and SP were both seen everyday,both the Mars light and the headlight were always on if they were leading a train.Ditch lights didn’t start coming around until around the end of the 80’s so most trains only had the main headlight to use.After the merger with Union pacific the single red Mars light on nearly all Southern pacific locomotives(except the SD70’s which were not built with them)started to disapear very quickly.This red light was used to warn the oncoming train if the track next to it was fouled by passengers,men or machinery or some other problem.Then the double beam Mars lights started to disappear from the SP locomotives.The D.R.G.W. locomotives on the other hand seemed to all keep theirs until they were either sold,repainted or rebuilt.It was rare after the UP merger to have either SP or D.R.G.W. locomotives in the lead with their special Mars lights.For those of us who grew up with them it was dearly missed espcially at night.

FRA rules state that if a locomotive has lights they must all work before the locomotive goes out.That includes marker lights,and mars lights.I’m sure in the later years if a locomotive had a defective mars light it was probably easier for the mechanics to remove it and keep the locomotive going instead of waiting for parts which could take weeks or months to arrive while the locomotive was sidelined.