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Directional running reversal

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  • Member since
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Posted by wjstix on Tuesday, November 21, 2017 3:17 PM

Capt.Brigg

I will be running the "reversed" engine in reverse at the end of a three engine consist.

 
Then why not just leave it? The way it is now, the decoder 'thinks' the long end of the engine is the front. If you're going to only run it in a consist with say two engines facing forward, and this engine as the trailing unit facing backwards, all you have to do is set up the consist with all three set to run "forward".
 
Remember, the decoder 'thinks' the long hood is the front, so that direction is forward for it. If you put the engine as it is now in a consist as a trailing unit facing backwards, and tell it go in the reverse of other two, it will go backwards when the other two go forwards.
 
Better yet, why not change the ID no. to the no. of the lead unit, if it's always going to work with it in a consist? I do that a lot, take two diesels that always work back to back and give both the same ID no., and set one's CV29 so it thinks backwards is forwards. Then I don't have to do any consisting.
Stix
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Posted by tstage on Tuesday, November 21, 2017 2:58 PM

No, it would still run forwards.  Front is front.

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by BigDaddy on Tuesday, November 21, 2017 2:48 PM

Doughless
IIRC, Athearn BB locos could run backwards if the front and rear trucks were switched.  So if the wiring looks the same from the top, maybe the leads of one loco is getting current opposite of the other because the trucks have been installed on the wrong ends.

So if I took my DCC loco that is running forwards picked it up and spun it 180 degrees and put it back on the track, it would run backwards? 

 

Henry

COB Potomac & Northern

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Posted by Doughless on Tuesday, November 21, 2017 2:28 PM

IIRC, Athearn BB locos could run backwards if the front and rear trucks were switched.  So if the wiring looks the same from the top, maybe the leads of one loco is getting current opposite of the other because the trucks have been installed on the wrong ends. 

- Douglas

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Posted by richhotrain on Tuesday, November 21, 2017 1:05 PM

Good point, Randy.

Rich

Alton Junction

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Posted by rrinker on Tuesday, November 21, 2017 10:46 AM

 True. There is a very slight possibility that it's the decoder, but since the orange and grey wires aren't right next to each other it's ard to get them swapped on the deocder itself.

If the issue is the magents, then the problem loco should run the opposite way even on DC. It's a little hard to flip the rail pikcup wiring when one side of it is the loco frame. This could be tested by disconnecting the decoder and using a 9V battery and see which way each motor turns, no need to completely revert it back to DC.

                             --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by richhotrain on Tuesday, November 21, 2017 7:36 AM

rrinker

 I still say it's the magnets. 

I should have mentioned in my reply that I agree with your assessment, Randy. It probably is the magnets. But, in the event that it isn't, if it were me with the OP's perceived level of curiosity, I would want to answer the two questions that I posed in my reply.

Rich

Alton Junction

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Posted by rrinker on Tuesday, November 21, 2017 7:30 AM

 I still say it's the magnets. There are two things that control the direction of a permag DC motor - the direction of current flow in the armature windos, and the polarity of the permanent magnets. The first is almost surely the same with both motors, so only the magnets are left. However, it is not recommended to disassemble the motor to fix this, as it can weaken the magnets and reduce motor performance.

                            --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by richhotrain on Tuesday, November 21, 2017 5:30 AM

Hmm, this is a bit of a mystery.

Let me ask you this. Did you buy both of these locos new or were they purchased used? I am wondering if a prior owner messed with the motor. Just trying to do some detective work here.

What if you removed the decoder on the problem loco and ran it on a DC track? Could the decoder be at fault?  Kind of a long shot but if your curiosity is getting the better of you....

Rich

Alton Junction

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Posted by Capt.Brigg on Tuesday, November 21, 2017 1:48 AM

I will be running the "reversed" engine in reverse at the end of a three engine consist. If I set the consist up with that engine assigned to the consist in reverse it seems like I will be setting up a double reversal. You can also add several throttle notches in NCE for kick starting the engine in reverse as they often start harder in reverse. It seems like I could be getting into some very complex codeing, while it will be much simpler to just switch the motor wires and leave the CVs where I expect to find them. I can fix the problem; I'm just curious why it exists.
Capt. Brigg, CEO
Pacific Cascade Railway in HO scale

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Posted by SouthPenn on Monday, November 20, 2017 8:25 PM

The lights will switch the proper way when you change CV29.

South Penn
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Posted by Anonymous on Monday, November 20, 2017 7:45 PM

tstage

Cap'n,

Why not just add a "1" to the value of CV29 (i.e. make it "51" rather than "50") of the locomotive running in reverse?  It would be quicker and easier than switching wires.

Tom

 

Wont that make the lights opposite direction?  

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Posted by tstage on Monday, November 20, 2017 7:43 PM

Cap'n,

Why not just add a "1" to the value of CV29 (i.e. make it "51" rather than "50") of the locomotive running in reverse?  It would be quicker and easier than switching motor wires.

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by Capt.Brigg on Monday, November 20, 2017 7:19 PM

Randy;
Yes the motors are facing the same way. They only fit between the trucks one way because they are offset with the brushes on one end.
Capt. Brigg

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Posted by rrinker on Monday, November 20, 2017 6:52 PM

 The rotors absolutely face the same way? Brushes on the same end of the loco?

Either the magnets are reversed, or one set of windings was placed on the shaft backwards, which seems unlikely as the solder points for the commutator segments are only on one end. My bet is on the magnets being reversed.

                           --Randy

 

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Directional running reversal
Posted by Capt.Brigg on Monday, November 20, 2017 6:10 PM

I have two Athearn blue box F-45s, built about the same time, with NCE decoders I installed on an NCE system with JMRI. With CV 29, the directional CV, set at 50 on both, using JMRI, one runs forward and the other backward. Both have the gray - wire on the top motor contact and the orange + wire insulated on the bottom contact. Both the headlight white wired, and the rearlight yellow wired LEDs work in the correct direction. Both motors are sitting in their cradels in the correct direction, one turns clockwise the other counter clockwise. Both engines can be turned on the track and will still operate the same. The only answer I can seem to figure is that one of the motors is wound opposite to the other motor. Is that possible, or what other answer could there be? I can fix the problem motor by reversing the wires, but the "why" is bothering me something bad. Any opinions are greatly welcomed.
Capt. Brigg CEO
Pacific Cascade Railway in HO gauge

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