Except when folks start talking about how roads ran their geeps, or looking for the small "f" on locomotives, etc. (which they have in this thread). It just, doesn't, matter......
Yes, absolutely. None of that matters. It's strictly polarity and direction. If I put a loco on the track with the front of the loco pointing left and the far rail is positive, it's going to move left. If I turn the loco around so the rear is pointing left and the far rail is positive, it's STILL going to move left. Doug
Thanks Doug! Hopefully the others have followed along and forgotten all the talk about reversing shells, looking for small "f's," etc. I'm sure we're all here to help!
I still remember getting straightened out about all that many years ago as a kid in the sixties by Linn Westcott in Model Railroader. Also all about reverse loops and other electrical subjects. A very smart man, he was. Passing it along just seems like the natural thing to do. Doug
Hi all Thank you so much for all the replies! Yes, indeed, my engines are trying to have a "tug of war". They run away from one another on the track. If anyone's wondering, the Atlas is the stronger puller! The frame of the atlas is designed such that the fuel and air tanks only fit one way, and I have the air tanks under the long hood. I know WM (and others) ran some of their units long hood forward, but as was said, they're running away from one another. "It doesn't matter which way the locomotive is facing. That's irrelevant. If the near rail is positive, it should move left to right, and if the far rail is positive, right to left." Thank you all so much! This is what I will check. I have had the Atlas apart (to cut the shell, etc to lower the nose) but don't recall ever removing the motor. The Kato was never apart aside from removing the shell to airbrush it. I will check polarity and flip motors as needed. Thank you again! Amanda
The Atlas is the culprit; near rail positive, it runs right to left. I guess I somehow got the motor flipped around? I'll see if i can flip it back.
If one looks at any model motor that uses a two piece metal frame to conduct the current to the motor there are contact points that get the current from the frame half to the motor, arranged so that one contact goes to each frame half. If the top and bottom contacts get reversed the effect is what you have had happen. The power pack is set for forward but when you open the throttle the locomotive goes in reverse. Just a simple matter to flip the motor so the contacts are back in contact with the proper frame side so the locomotive responds to the set direction on the power pack. It is what I clearly stated on page one of this thread and I agree with the Norseman said about all this business about what roads ran what hood forward, or where the F is located on the frame sill. You clearly stated the problem in your post so I don't know what part folks did not understand.
I have disassembled, cleaned, and reassembled several older Kato F7 AB units and invariably put the motor in backwards without realizing it until I ran them on the track. It is very easy to invert these older Kato motors.
Wow, lots of responses for a problem that is easily fixed. This problem shows up when a locomotive is taken apart for maintenance or for doing decoder installs in engines where the motor must be isolated from the frame. Every instruction I have seen for such installs state the same advice. That is you should mark the top of the motor so that when you re-install the motor you can tell which is the top and which is the bottom and re-install the motor the same way. So you can forget about left or right or which rail is positive or negative. The problem is the motor is upside down. Switching the motor so that the top is on the bottom will cause it to run in the opposite direction from all the other locomotives because now the moptor contacts are touching the opposite frame half than they should. Flipping the motor over so that the top is on the bottom will cause the motor contacts to contact the opposite frame half reversing the direction of the flow of electricity in the motor. So find out which engine is the wrong way odd ball then take it apart turn the motor over top to bottom 180 degrees then reassemble and enjoy the Eureka moment.
This doesn't directly pertain to WM183's issue - but, what I do when I first take a locomotive apart - (for any reason) - I scratch a "T" on the top of the motor (Before complete disassembly of the chassis). So, I know the orientation of the motor when reassembling the locomotive. Wolf
That is a really good idea. I will have to this from now on. It's all fixed now, but for the future I will want to avoid such problems.
Though MILW modelers might wish to purposely invert a motor to replicate a locomotive vs locomotive contest.
Yes, I believe that most of us understood this from the beginning. Since the OP only had two locomotives (and a multimeter), we were trying to help him figure out which one was reversed. That's why we were discussing polarity of the rails and which way was correct.
I believe all DC power packs have a 'Direction' switch on them . Throw that switch to the left and all engines that are in front of you will go from right to left. The one that doesnt is the one thats screwed up. Simple...no technical babble...Just Sayin.
What if the direction switch on your power pack is oriented up and down? (jk) I'm sure you are aware that it could all be the reverse of what you stated if the wires to your track are reversed. The OP had only two locos, but had an electrical meter so we (at least some of us) were trying to help him figure it out with what he had to work with (even if it required some "technical babble"). Hopefully electrical polarity is not technical babble to any model railroader (although, I can't say the same for the general public).
Not technical babble for me at all - I was an electrician before my move to the Netherlands, and if i can navigate the certification process here (and learn the language!) I may be again. Thank you all for the answers. The loco is fixed and now behaves as it should! Amanda
