Red Mars Light

Briefly, when a locomotive goes into emergency brake application, the lead unit red mars light activates...it signals any opposing movements to stop.

The new BNSF diesels have a red cab light that comes on inside when they go in emergency. Once you reset the penalty and recover the air, the red light goes out.

Rob Leese posted:

Briefly, when a locomotive goes into emergency brake application, the lead unit mars light activates...it signals any opposing movements to stop.

I don't think that is what he is asking about. He seems to want to know, if I read his last sentence, which is the question, how did red become a stop signal? Maybe he could be a bit clearer concerning exactly what he wants to know.

If one wants to know why red became a signal for "stop," Googling "why does red mean stop" will answer the question.

OK, RED MEANS STOP.  But WHY place it on the front of a locomotive, like the one which was on UP 844? That is the "system" I was referring to.

Dominic Mazoch posted:

OK, RED MEANS STOP.  But WHY place it on the front of a locomotive, like the one which was on UP 844? That is the "system" I was referring to.

OK, but you really did NOT make it clear.

Many railroads with extensive miles of double track main lines, opted for the Mars Red Signal light, which was activated by an emergency brake application. Operating rules dictated that no opposing train on the addict track was allowed to pass the train stopped in emergency with the Mars red warning displayed. Once the train had been fully walked/inspected, with assurances that the adjacent track was not fouled, only then would the Engineer recover the train air brakes and reset (turn off) the red Mars light. Lots of railroads with extensive double track purchased Mars Signal Lights, both red and white.

Hot Water posted:

Many railroads with extensive miles of double track main lines, opted for the Mars Red Signal light, which was activated by an emergency brake application. Operating rules dictated that no opposing train on the addict track was allowed to pass the train stopped in emergency with the Mars red warning displayed. Once the train had been fully walked/inspected, with assurances that the adjacent track was not fouled, only then would the Engineer recover the train air brakes and reset (turn off) the red Mars light. Lots of railroads with extensive double track purchased Mars Signal Lights, both red and white.

Thanks for the info. Like Dominic, I've also long wondered why you'd need a stop signal on the front of a locomotive. Makes sense, now that you've explained it.

what Hot Water describes is exactly how the DL&W used the red warning light found under the headlight on many of their F3 diesel engines.

for the road, it was also used for a pair of helper engines on the rear, where the second A unit faced rearward. the red light was displayed if the train was stopped.

PRR Man posted:

what Hot Water describes is exactly how the DL&W used the red warning light found under the headlight on many of their F3 diesel engines.

I think you will find that due to the size, weight, and complexity of the Mars Signal Light assembly, it was generally mounted in the upper position on F Units, while the headlight, being lighter & smaller, was mounted in the door. Thus, crew members would be able to open the front nose door easier.

Watching a Mars light working was very interesting !

I noticed on some photographs the Mars light on some diesels was sometimes red and other times clear.  This puzzled me until I saw the Train of Tomorrow promotional film.  The mechanism was set up to switch the lights from clear to red and vice versa.

It's shown about 1:10 into the film.

Fascinating.

Rusty

I noticed they removed the red Mars light from 844 after its latest overhaul. Explain that one?

N&W 1218 posted:

I noticed they removed the red Mars light from 844 after its latest overhaul. Explain that one?

Explained on the UP844 Video w/update thread below.

Jack, I don't think the DL&W F units had actual Mars lights, but a red warning light. They were smaller than the headlight.

Concerning the DL&W emergency light, I have never seen a reference to using it as a rear marker in pusher service in any DL&W rule book or timetable.  Old timers I have spoken with over the years confirmed that it was strictly an automatically activated warning for opposing trains. Before the days of reliable radio communications between locomotives it was a method of warning of the possibility of  fouled adjoining tracks by the train that displayed the light.  As radios improved, the need for the light was lessened.  Hence the DL&W removed most of them. 

Having grown up (and still residing) along the western slope of the Pocono Mountains and having watched hundreds of pusher units, I never saw them lit.  Indeed I saw the rear headlight on dim, if so configured, or the regular markers displayed.  By the time of the EL merger, quite often there were no lights displayed on the rear end of the pushers at all.  A few had a rear headlight for the return trip down the hill if the unit(s) were forward facing the train.

On a humorous note, as kids we thought the light pushers returning from the shove to Lehigh, clearly labelled "Radio Equipped", were  "Radio" trains looking out for trespassers like us. I can't tell you how many times we ran for the woods to hide from sight.  We were sure that we could go to jail for squirting  each other by jumping on the flange oiler button ....... but I digress.

Earl 

Earl,

Glad you cleared that up, as I was raised on the DL&W during the mid to late 1950s, and NEVER saw that red light on the front nose door illuminated when units were on the road. However, I do remember seeing one or two A Units at the Henderson Street engine terminal in Hoboken, with the red light on. That would have meant that the consist was in emergency, probably while they were changing ends.

Very interesting.  I must admit I can't imagine why they would put the unit(s) into emergency to change ends.  Perhaps there is more to learn here.  A lot of the day to day procedures of railroading, not necessarily found in rule books,  from that golden age are being lost as the old timers pass away.  This is one of the questions I could have asked my late mentor Willard Benjamin who worked Hoboken from time to time. He had a mind like a steel trap and could answer any question my little mind could ask.  

These kinds of discussions are a great way to learn from each other.  Thanks for sharing the information.

Earl         

Earl,

Lots of strange things can happen when someone who doesn't know exactly what they are doing, either breaks apart a consist of units, adds a unit to an already established consist, or simply changes ends. That is why there all those piles of sand on the tracks within engine terminals, i.e. the air brakes go into emergency, and the emergency sand comes on, as well as any red warning lights.

Wyhog posted:

. . . just wanted to point out that the red warning lights were not only for multitrack territory.

In Automatic Block Signal territory, single track, Santa Fe Rule 509(a) required the display of the red oscillating headlight on engines so equipped (i.e., passenger diesels) while proceeding through a block from a Stop and Proceed signal indication.

I have never been able to determine what incident prompted the railroad to add this rule, but -- back in the days before cab radios were common, it would have at least indicated to any train ahead, that the train displaying the red oscillating headlight was advancing at Restricted Speed.

also glad for the clarification on DLW pusher service. the only reference I've ever seen in operating manuals noted the opposing traffic warning use.

apologies for the misinformation.

Tom,

The Santa Fe 509(a) rule is another interesting and unique use of lights and other signaling devices in the days before good radios.  I love this thread.

Thanks for sharing.

Earl

As added information, the red/white Mars and Gyralite oscillating headlights had control switches above the side window on first generation diesel units, and on later locomotives built with cash register style control stands, used a rotary switch.  The positions were Bright, Dim, Off, and Red.  the motion control switch was integrated into the old style control, and adjacent to the new style.  It was a snap switch with Off as the center position, Run in the "up" position and Spot, spring loaded in the "down" position.  Spot allowed the Engineer to move the headlight and stop it at any position within its sweep.  I have been told that D&RGW Engineers often used the Spot position to point the headlight into a curve in some of the straight up and down canyons of that road.