Layout newbie here: Is there a convention for which rail is positive for a DC system?
Engineer's side or Fireman's side. In one of Mark Shutzer's clinics, engineer's side is shown in red and opposite side black. Should one assume that it means engineer's side is always to be positive?
Thanks,
Ed
I'm not aware of such convention. And it would assume that locos always run in the same direction. On my old DC layout, which had a loop, I generally ran my locos counter-clockwise so I could see the cylinders of my Shays. But otherwhise, I don't think there is such a convention. Let's see what the DC gurus will say.
Simon
I have never done more than to ensure the 'outside' rail, the one closest to the wall, gets one colour of insulation. Naturally, with only one rail left, and a choice of other colours,....
I know of no 'convention', just the absolute requirement to be consistent about the wiring so that one doesn't get tripped up and wonder why he can't figure out the short.
cnjman721Is there a convention for which rail is positive for a DC system?
Direction control by polarity reversing shall be provided. Positive potential applied to the right hand rail shall produce forward motion
greg - Philadelphia & Reading / Reading
cnjman721Layout newbie here: Is there a convention for which rail is positive for a DC system?
If you are talking about layout and track wiring, then there is no such thing. Your direction switch on the power pack will change which rail is positive and which is negative to control the locomotive direction of travel.
If you are talking about locomotive building/repair, then what Greg said is true. If this is not followed, you will have a locomotive that runs in the opposite directions of the others in relationship to which position the direction the switch is set.
If you need more information or explanation, please ask.
-Kevin
Living the dream.
If you are going block control, I recommend running a train or at least engine from your first block to your second as soon as the second is wired. If it works, do the third section, if it doesn't work you know where you went wrong. If one big block, check after two or three pairs of drops.
SeeYou190Your direction switch on the power pack will change which rail is positive and which is negative to control the locomotive direction of travel.
gregcIf your direction switch is mounted left/right, you'll probably want it wired so that when to the right, the inside rail is positive
Sorry Greg, I have never put any thought into it.
I want the train to go to the right when the switch is to the right. If that is not what happens, I just reverse the wires on the power pack. Then it works as desired.
According to the LION... The PORTSIDE rail is GROUND, and the STARBOARD rail is powered.
Apply +12v DC to the starboard rail and the train moves forward. Apply -12v DC power and the locomotive wioll move in reverse.
Port abnd starboard, like aboard a ship assumes that you are on the ship (or locomotive) and are facing forward. The starboard side is on your right, and the port side is on your left. If you turn around port and starboard do not move around. They are a fixed designation.
ON RAILROAD of LION tracks are wired wwith the intention that the locomotive will move forward, thus the left (portside) rail is GROUND, and the right (starboard) rail is your power rail. When looking at the tracks we always assume that you are looking in the direction of travel, (usually timetable direction on a single track line.
Railroad of LION is a double track point to loop layout, the front of the train remains in the front for the train's entire route. Left track GROUND, right track POWER. Subway trains of LION do not move in reverse--there is another train 90 seconds behind the leader, and besides the signals will not allow it.
THUS... if you wish to make several blocks with a number of different transformers, you need only connect the (-) output from each transformer to GROUND. You will need only single pole selection switches to connect a block to this tranformer or that, and of course the reversing switch on the transformer will work as expected.
This system also allows several other transformers to be connected to ground and give you a variety of outpust for other services.
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
The only convention in ADC wiring (or any DC wiring for that matter) is DONT touch the wires together! Other than that, there is no set way to wire your track. This is due to reversing loops, controlled blocks, Wye's, etc.
If your just running a loop around the XMas tree, its fairly simple to do. Pretty much as Kevin said above, if the direction of your loco doesnt move the direction you think it should..... reverse the wires.
However, do know some manufacturers, or a used model thats been 'fixed' by a non-experienced person, may not work like your other locos. If you have 5 locos, 4 of which run the correct way and one doesnt, then the wiring inside the oddball model needs to be switched. Dont be fooled, and go rewiring your layout!
Respects,
PMR
PM RailfanHowever, do know some manufacturers, or a used model thats been 'fixed' by a non-experienced person, may not work like your other locos.
Yes, this is especially true of Athearn Blue Box locomotives. If one is taken apart, then assembled with the front and rear trucks reversed, it will run the opposite of how it is supposed to.
I have bought a couple that ran incorrectly. It is an easy fix.
I don't recall ever worrying about which wire went to which rail...these two power my entire layout...
If I want a train to go in one particular direction, I simply flip the direction switch on my hand-held walkaround throttle to the desired position, and that's the direction in which it moves...
The only exceptions are on the layout's two turntables, where the direction is controlled by double-pole/double throw/centre-off switches.
With the layout being an around-the-room type, you simply walk around with the hand-held throttle, technically looking North, and the train is either heading East (to the right) or West (to the left)Here's a sketch (minus a trackplan) of the layout...
The area in grey has since been covered by a partial upper level, and so far, with no explanatory captions.Here's a couple partial views of it...
Wayne
I hope the OP returns with some additional comments or questions.
Greg --
Thanks for the link to the NMRA standard. Exactly the answer I was hoping for.
gregc cnjman721 Is there a convention for which rail is positive for a DC system? yes, defined in NMRA standard S-9 Direction control by polarity reversing shall be provided. Positive potential applied to the right hand rail shall produce forward motion
cnjman721 Is there a convention for which rail is positive for a DC system?
yes, defined in NMRA standard S-9
Good catch, Greg. I had never seen it, and I can understand its reason for being there.
cnjman721Greg -- Thanks for the link to the NMRA standard. Exactly the answer I was hoping for.
Way to go Greg!