Mars light on Union Pacific Big Boy.

[DAV]

What was the red or amber light used for on the big boy ?. The light is just above the back-up light on the tender, it sits on the top of the water tank. It flashes on and off during a lash-up .  What was it's purpose .

 

 

[cnwfan51]

Are you sure its a bigboy I just lookied at Bill Kratvilles Book Motive Power of the Union Pacific and didnt see any mars light on a tender, The only thing I can think of would be if it used as a rearend Helper and it might be use as a marker light Larry

[DAV]

Larry

 Here is a picture of the light , it's just above the rear light on the tender.

 

http://www.railarchive.net/bigboys/up4002-4.htm

[cnwfan51]

BY Golly you were right I still think that is for a rear marker light when ever it was running light or in pusher/helper sernice

[DAV]

pusher/helper sernice?. do you mean lashed-up , then the light would  would strobe, MARS ?.

 

[wjstix]

When an engine pushes at the end of the train as a helper, it needs to show something to rear to indicate it's the end of the train. Some steam engines had places on the tender to hang marker lights (like a caboose did) but some had a rear headlight or other light that could be used instead. I suspect the larger light on the tender here was the regular rear headlight, and the smaller light above it was a red light (probably not a flashing Mars light I'd guess) used when the engine was pushing at the rear of a train.

[AgentKid]

Different RR's had different polices regarding pushers.

On the CPR they were coupled in ahead of the caboose. This was to prevent the rear engine from crushing the caboose and crew in the event of a sudden stop of the train. Other roads did couple on behind the caboose. I don't know what UP's policy was, but that does seem to be a marker light.

Bruce

 

[Bob-Fryml]

Keep something else in mind too.  Steam locomotives used as helpers - whether coupled to the head end or pushing from the rear - upon reaching a summit would cut off from the train being assisted.  After turning, the engine would then run light as a train back to its original terminal.

Rules books of that era defined a train as an engine, or more than one engine, coupled with our without cars, displaying markers.  The red light permanently attached to the back end of a locomotive tender fulfilled the "markers" requirement.