Directional running reversal

[BigDaddy]

I get it now.  Thanks

 

 

[Capt.Brigg]

From one old guy to several others, I will share with you that while Direct Current (DC) has track polarity, Digital Command Control (DCC) does not. DCC is essentially Alternating Current (AC) with a control signal on the power. The decoder then converts the AC to DC and sends it to the motor with the polarity set depending on which way the controller is telling it to go. There is no + or - on the rails and the wheels or trucks or truck towers do not see a polarity and can point in any direction with no change to the DCC controller or the power to the motor.

Going on an earlier suggestion that the internal motor magnets may have been reversed, and wondering if 40 years ago I may have disassembled the motor and reassembled it in reverse and then forgot; after Thanksgiving I am going to disassemble the motor (again?) and see if I can identify how it could be reassembled in the proper direction. I did buy this engine new, so if someone changed the motor, it must have been me. Stay tuned for the results of my little learning exploration.

Yes the lights could be directionally changed using a CV in the decoder to match the engine direction, but that is just putting a patch on a sore, and not healing the wound. I want the coding in all the engines to start out the same.

Capt. Brigg, CEO Pacific Cascade Railway in HO gauge.

[Anonymous]

Capt.Brigg

Going on an earlier suggestion that the internal motor magnets may have been reversed, and wondering if 40 years ago I may have disassembled the motor and reassembled it in reverse and then forgot; after Thanksgiving I am going to disassemble the motor (again?) and see if I can identify how it could be reassembled in the proper direction. I did buy this engine new, so if someone changed the motor, it must have been me. Stay tuned for the results of my little learning exploration.

It could have been a what we call a Monday morning motor or a Friday afternoon motor, all the way from the factory.  

[richhotrain]

Capt.Brigg

Going on an earlier suggestion that the internal motor magnets may have been reversed, and wondering if 40 years ago I may have disassembled the motor and reassembled it in reverse and then forgot; after Thanksgiving I am going to disassemble the motor (again?) and see if I can identify how it could be reassembled in the proper direction. I did buy this engine new, so if someone changed the motor, it must have been me. Stay tuned for the results of my little learning exploration.

That was my question back on Tuesday when I asked if you bought the loco new or used. My thought was that if it was used, the prior owner may have disassembled and then reassembled the motor.

Rich

[zstripe]

In case anyone would care to read about how a DC motor like We are using in our engines whether it be DC/DCC.....Athearn and all the others I have experienced follow the Right Hand Rule when it comes to wiring the N & S poles of a DC motor:

http://web.mit.edu/cmse/educational/motor_lp_kristy.pdf

I actually built one similar to the above, way back in the 50's when going to school. They also had cheap kits back then to make Your own DC motor. I'm sure Randy has played with one at one time or another.

Take Care! 

Frank

[richhotrain]

Frank, that is a great link.  Very informative tutorial.

What is the difference between this type of DC motor and a "can" motor"?

Rich

[Doughless]

Capt.Brigg

From one old guy to several others, I will share with you that while Direct Current (DC) has track polarity, Digital Command Control (DCC) does not. DCC is essentially Alternating Current (AC) with a control signal on the power. The decoder then converts the AC to DC and sends it to the motor with the polarity set depending on which way the controller is telling it to go. There is no + or - on the rails and the wheels or trucks or truck towers do not see a polarity and can point in any direction with no change to the DCC controller or the power to the motor.

 

Capt. Brigg, CEO Pacific Cascade Railway in HO gauge.

 

But the controller doesn't know which way the loco is pointed.

If you install a decoder that's set at factory default, and reverse the motor leads or install the truck leads opposite of how you install them in another loco, it will in fact run backwards relative to the other loco, right?

[woodone]

The trucks will NOT make any difference. The wiring on the motor would..

[Doughless]

woodone

The trucks will NOT make any difference. The wiring on the motor would..

 

Ok thanks.  I get it.  I was thinking of a standard PC Board without the decoder. 

[Capt.Brigg]

Doughless

But the controller doesn't know which way the loco is pointed.

The  DCC controller does not need to know which way the engine is pointed, it just knows if the engine should go forward or backward, at your command from the throttle. The engineer (you), need to know which way the engine is pointed.
Capt. Brigg

[doctorwayne]

zstripe

Wayne, Don't have a clue as to what happened to My post above..it also timed out....

Not a problem, Frank. 

All I know is that when I re-trucked my four Athearn switchers, I didn't pay attention to which truck went on which end, with the result that two ran in the opposite direction of the other two, and opposite to all of my other locomotives, too. 
Of course, I run DC, so am not all that familiar with the niceties of DCC, although I've heard that it makes wiring simpler.

Wayne

[Capt.Brigg]

The final solution is at hand.

This afternoon I solved the puzzle of why my 40 year old PCRy engine motor turned counter-clockwise while all the other Athearn motors turned clockwise, with the same polarity DC power applied to the motors. Somewhere back in forgotten time, I took the motor apart and then reassembled it with the center magnet reversed. So, today I again took it apart, turned the tubular magnet, reassembled it and it now turns clockwise like it is suppose to do.

When dissembling the engine you will need to twist the weights to pry them off the ends of the motor shaft. Other than that be very careful when you take the brass straps off the top and bottom or you will loose the small spring and brushes under each one.
Capt. Brigg; A little smarter today.

[rrinker]

Darn magnets....

I think it was explained well above, but the polarity on the rails is meaningless for DCC. Say you had the red wire on the righ rail, and the black wire on the left rail. Flip the direction switch one way on the DC power pack and turn it on. The loco will move one direction. Touch NOTHING else, but move the red wire to the LEFT rail and the balc wire to the RIGHT rail - the loco will run the other direction. Now repeat with DCC instead of a DC power pack (and a decoder in the loco). No matter which rail you connect the red wire to and which you connect the black wire to, the loco always moves the same way as long as you don't touch the direction switch on the throttle.

 That's why reverse loops are so easy with DCC - you can change the 'polarity' of the DCC track power under a moving loco and it won't miss a beat, and continue on in the same physical direction.

                          --Randy

 

 

[Capt.Brigg]

rrinker

That's why reverse loops are so easy with DCC - you can change the 'polarity' of the DCC track power under a moving loco and it won't miss a beat, and continue on in the same physical direction.

Randy, let's be complete with your information. With DCC you do have to have an electrical gap at each end of the reversing loop to prevent a short, and if an engine crosses that gap without some sort of electronic polarity reversal component, the engine can cause a short circuit at the command station.

Thank you all for following this thread and my journey of re-discovery.
Capt. Brigg; CEO Pacific Cascade Railway in HO gauge.

[richhotrain]

Capt.Brigg

 

Randy, let's be complete with your information. 

While we're at it, lets be sure to give Randy the proper credit for coming up with the solution in the very first reply to this thread.

Rich