Hi guys, is there a standard on which rail (inner or outer) to apply positive and negative wiring?
Well, it refers to "right hand" and "left hand" rails rather than "inner or outer", but the NMRA's RP9, paragraph II says, in part, that:
"Positive potential applied to the right hand rail shall produce forward motion. (3) "
Then, (3) goes on to say:
"(3) The term "right hand rail" as used herein means the rail to the right of the observer standing between the rails with their back to the front of the locomotive. "
It doesn't exactly cover your question, but I think it's the closest to such a standard that exists, unless one of the modular groups has something more specific.
Are you speaking of 2 rail or 3 rail?
2 rail DC - it doesn't matter. You reverse the polarity to reverse the direction of the locomotive. However, with any 2 rail system you must stay consistent - the nominal positive always goes to the same rail, and the nominal negative always go to the same rail. If you don't like the direction of the locomotive in relation to the direction switch on the power pack, reverse which rail gets which polarity - easiest done by swapping the wires at the power pack terminals.
3 rail (often uses AC instead of DC). "Ground" or "common" usually is the outer rail - the convention came from Lionel's traditional wiring (and prototype practice). Most 3 rail track ties the 2 outer rails together at every track section. "Insulated" track sections isolate one of the outer rails, usually to feed an accessory. The wheels of the train, being uninsulated in 3 rail, bridge the 2 outer rails to complete a circuit to the accessory. Note that the middle rail can be moved to an overhead (trolley or pantograph pickup) or outside 3rd rail (many subway systems) - the principles are still the same.
hope this helps
Fred W
I think the NMRA response is great. Let me add. I"m right handed and so back years ago in the DC universe--LOL I always wired so that the direction switch was to the right and that meant I would be facing right and so that would be the right hand rail which was the NMRA way too. And obviously all you've got to do is flip the switch.
Seriously though if you plan on using common rail ground you should study the NMRA website on wiring common rail ground type wiring. I found it worked well for the DC set up. No sense in repeating everything here when they have a great website with pics all there for you.
Richard
thanks everybody I'm going to the NMRA website
StevertWell, it refers to "right hand" and "left hand" rails rather than "inner or outer", but the NMRA's RP9, paragraph II says, in part, that:
The POSITIVE wire on the STARBOARD rail produces FORWARD motion.
Fore and Aft, Port and Starboard do not change no matter how you look at things.
LION has his PORT rail connected to GROUND, reversing switch then applies either + voltage or - voltage to the Starboard rail depending on the position of the reversing switch.
Sounds complicated, but with this protocol you can set up several blocks and cabs with only ONE wire to each which permits the use of less wire and cheaper control switches.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
reelalHi guys, is there a standard on which rail (inner or outer) to apply positive and negative wiring?
BroadwayLionFore and Aft, Port and Starboard do not change no matter how you look at things.
Wouldn't the orientation of the loco change the results? If the loco is facing to the right on a loop so it goes counterclockwise around the loop,, then the rule would make the right hand, or outside rail be the +. If the loco is facing to the left, then the opposite would be true, with the right hand, or inner rail being the +. what am I missing?
floridaflyer Wouldn't the orientation of the loco change the results? If the loco is facing to the right on a loop so it goes counterclockwise around the loop,, then the rule would make the right hand, or outside rail be the +. If the loco is facing to the left, then the opposite would be true, with the right hand, or inner rail being the +. what am I missing?
Yes. That's why I included the NMRA's note (3) with my reply. It specifies under what circumstances a rail is considered the "right hand rail". Those circumstances include which way the loco is facing.
So if the loco is facing the opposite way, the OTHER rail becomes the "right hand" rail, and to have the loco move forward you'd then need to apply the positive power to that OTHER rail instead.
This standard has nothing to do with how a layout is wired and everything to do with how a locomotive is wired. The layout reversing switch can change polarity or you could swap wires at the power pack.. But the locomotive will still respond to the right rail positive in forward.
This typically becomes an issue when someone swamps trucks on a Athearn type or installs a aftermarket motor and does not observe the proper polarity. The symptom will be an engine which runs opposite every other one on your layout.
Jim
Texas Zepher BroadwayLionFore and Aft, Port and Starboard do not change no matter how you look at things.Lions on ships! I not think that a natural state of affairs.
LION was in NAVY. Him is a SEA LION!
See. LION is on STARBOARD wing of F4. Turn the F4 around and the LION is still on the starboard wing.
If the airplane were on railroad tracks and an 0-5-0 switcher turns the locomotive around the left rail would become the right rail, but unless you also change the reversing switch the locomotive would still move in the previous direction regardless of which end you think is the front.
So forget the locomotive, it is only track that matters. You stand at milepost zero and look north, the rail on the east side is POSITIVE, and the west side is NEGATIVE, and the train will move NORTH.
The reversing switch is not FWD and REV, but rather EAST and WEST (Or North and South on the NYCT)
BroadwayLionHim is a SEA LION
Or maybe a CAT fish.
Exactly. Which rail is wired to which terminal of the power pack makes no difference, if the loco is wired per NMRA standards then it will move fordward (from the engineer's point of view) when the right hand rail (fromt he engineer's point of view) is positive. Back in the day when we only had room for a 4x8 + a little more, I tried o hook them up so that the direction switch refelcted the direction the train moved when in front of the control panel. Of course, when the train was on the back half of the loop, the direction switch pointed the opposite way. Oh well. For a shelf-type DC layout, you can keep it pretty consistent. If there are fascia mounted direction switches, well, it makes sense to wire them so that the handle position indicates which way the train moves - be a cruel trick to have them opposite, and reverse the E/W (or N/S) markings - people would get used to it, but you'd have a ton of backing off the end of sidings or backing into a following train before they caught on.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Lion,
Thanks for the Mini Lion shot,that was great!! And also the,Port,Starboard,which is also correct. My old way of looking at it,they used to say, North and South rail,when I started in the Hobby upteen years ago..On this side of the World, the sky is North and the South is ground. Now in JaBear side of the World, the sky is South and the North is ground. Something to Think about!?!
Cheers,
Frank
Well, if the tracks go east and west, then you have a north and south rail, but if the tracks go north and south, then you have an east or west rail.
As for the north-south vs east-west, various prototype railroads had their own conventions. Regardless of the actual map direction the rails ran, they generally adopted one or the other as the way to describe direction for use in timetables and so forth.
Exactly,,If you are facing North,would not East be on your right,,whichever way you face, +POSITIVE is the right rail, as far as a Model electric motor is concerned. It is still fun !?!