1:20.3 55 Ton 3 truck shay questions

[gprice]

Hi, I have a couple of questions about my 3 truck shay.
Behind the smoke box door there are 2 switches;
1. Smoke which is self explanatory and
2. NMRA/Direction/Large Scale.
Question 1 is what is the purpose of the 2nd switch?
Question 2 is if I convert the loco to battery R/C is the 2nd switch relevant?

[Chuck N]

NMRA standards have a different polarity to the engine motor (s).  If you have LS engines from other makers a Bachmann engine will run in the opposite direction if the switch is set to NMRA.  if it is set to LARGE SCALE every thing will go in the same direction for a given direction setting on your power supply.

Chuck

[Loco Bill Canelos]

Hi gprice,
Chuck answered question one perfectly.  As for question 2, a lot can depend on how you do the wiring.  In my April 2014 Garden Railway Magazine article on battery powering the Annie, I wired that switch to allow the loco to be used for track power in one position and battery power in the other position.  I used one position to isolate the loco from the track. You can look at the article to see what I did and why.  Generally speaking you could also do it with the Shay.  I cannot get into specifics on the 3 truck shay because I do not have one.  If you never want to use the loco with track power you can just remove or disconnect the track power contacts then the 2nd switch would become irrelevant.  There are many ways to wire a loco when converting and each method comes with its own problems. 

Have fun with your conversion!!

Bill

[gprice]

Thank you for the replies, they will be a great help

[Chuck N]

G:

I learned about this the hard way.  I was getting ready for a train show and I bought the newly released Thomas set.  I had a track plan where I could change the polarity on the track and train A would start and train B would stop on an adjacent passing siding.  Unfortunately Thomas ran in the wrong direction.  I had to rewire him so he would run with his new friends rather than away from them.  Now, thankfully Bachmann has the switch.  Later Thomas's have the switch you mentioned.

Chuck