Large Scale Central

Why are Aristo's trail car plugs opposing polarity?

Electronics Power and Sound
#1

There must be a good reason, but I can’t think of it. To M/U two Aristo locos using the supplied power plugs one needs to create a crossover cable.

When wiring up my own version of their system I keep the polarity the same at both ends and use a straight through cable. Of course, this means I need two sets of M/U cables. One for Aristo and one for everything else.

The reason could be obvious and just alluding me. I’ve only had two small cups of coffee so far today :slight_smile:

#2

Answering my own question… There is a very good reason. After a 3rd cuup of coffee and some experimenting it quickly became clear.

If there is no cross-over of polarity from end-to end in the loco, when you flip the loco around in respect to the trail car it will push the train backwards when the R/C throttle is in forward. When wired as Aristo does, Forward is the front end of the trail car regardless of which way the loco is oriented.

:o Doh !!!

So now I need to decide. Do I follow prototype where Forward is moving toward the Front of the loco, or do like Aristo and all track powered trains where Forward has to do with which rail has the positive power regardless of the orientation of the loco???

Logically, for trail car operations (especially mine with direction indicators) I think Aristo got it right. On the other hand, a loco with On-Board R/C operates like the prototype, so if running with the loco flipped around, you run in reverse to make the train go forward.

Oh bother.

#3

IYRR,RIYW

#4

I’m so cornfused… I got all turned around on that one… :frowning:

#5
Andy Clarke said:
I'm so cornfused.... I got all turned around on that one.... :(
Honest, he does. Really.

The front of the unit is the front and marked with an “F”. Unless you are “era conscious” and certain railroads, like the Norfolk Western and the Southern, plus a few others, ran the long nose forward. So if you lash two powered box cars together with each unit facing the opposite direction and they both have an “F” on the front of the unit, then either direction is going forward and the opposite is going in reverse, unless the crew is in the other unit. So many modelers think that if the headlight is on the unit it is going forward, but actually it is if the crew is in the unit facing the direction the unit is going then it is going forward. However, some modelers refuse to remove the engineer from the seat when the unit is going the opposite direction. And of course, there is a prototype for everything, so you can’t be wrong and even during the Chessie Era, they always ran their units "elephant style, unless one was facing the other direction.

So in answer to your question, Jon. If the plugs fit together, you’ve got it wired correctly, if they don’t, you don’t.

#6

I started a reply, but I need to do some more testing to answer. I usually run the 45T’s elephant style because there really is very little difference in the ends and with a trail car, the rear loco doesn’t get used in switching like an m/u pair would be.

#7

OK - Here is the scoop. Based on my current wiring scheme where the polarity of the plug is the same on both ends.

Single Loco

Connected to trail car F end leading. R/C in Forward (Trail car green LED on front) - Loco travels in the F direction pulling the train.

Connected to trail car F end Trailing. R/C in Forward (Trail car green LED on front) - Loco travels in the F direction pushing the train.

Above is prototypical but confusing due to LED indication on trail car.

M/U Locos - Connected with cross-over M/U cable

Elephant Style F End leading. R/C in Forward (Trail car green LED on front) - Rear Loco travels in the F direction pulling the train, but lead loco runs opposite fighting movement. Not workable with crossover M/U cable.

F at Opposite Ends / Rear loco connected to trail car F end Trailing. Front loco connected to rear loco F end Leading. R/C in Forward (Trail car green LED on front) - Rear Loco travels in the F direction pushing the train. M/U unit follows correctly.

Same as above but with R/C in Reverse (Trail car red LED on front) - Front Loco travels in the F direction pulling the train. M/U unit follows correctly.

I didn’t test them connected F to F with R leading on the font loco because I don’t operationally see this happening often.

I like the idea of only having one type of M/U cable to deal with regardless of what engine and what orientation. At the same time I prefer my trail car LED to indicate direction of train travel. I don’t see that happening unless I re-wire one end of both locos :frowning:

For now I may just make up one straight through M/U cable and run them elephant style. At least that way having engineers on both won’t look quite so silly :slight_smile:

Another option would be to add a DPDT M/U switch on the trail car to change the polarity of the output plug depending om how it is to being used. This may be the simpler solution to implement and most flexible…

#8

Why don’t you run the same cable for everything and set the default start up direction of the loco you want to run backwards in the consist?

BTW. The Aristo cables are wired backwards in some SD-45’s and some Dash 9’s.

#9
Ric Golding said:
Andy Clarke said:
I'm so cornfused.... I got all turned around on that one.... :(
Honest, he does. Really.

The front of the unit is the front and marked with an “F”. Unless you are “era conscious” and certain railroads, like the Norfolk Western and the Southern, plus a few others, ran the long nose forward. So if you lash two powered box cars together with each unit facing the opposite direction and they both have an “F” on the front of the unit, then either direction is going forward and the opposite is going in reverse, unless the crew is in the other unit. So many modelers think that if the headlight is on the unit it is going forward, but actually it is if the crew is in the unit facing the direction the unit is going then it is going forward. However, some modelers refuse to remove the engineer from the seat when the unit is going the opposite direction. And of course, there is a prototype for everything, so you can’t be wrong and even during the Chessie Era, they always ran their units "elephant style, unless one was facing the other direction.

So in answer to your question, Jon. If the plugs fit together, you’ve got it wired correctly, if they don’t, you don’t.


Lets complicate things a little more… Say you have a train a locomotive plus some cars. The locomotive is always the ‘front of the train’ right? Nope. Here’s why and it’s called a reverse movement (and a whole rule to go with too). The train and locomotive are heading east. The locomotive and train stops. The train then moves backward to set out a car moving West. The westward end of the train is now the ‘front’. The locomotive stops again within the controlled blockwith a controlled block signal (it crossover or any other dispatcher controlled). Remember the locomotive is now the rear of the train heading west. Before you can move East again (and change the rear of the train back to the rear, and the front back to the front) you must get permission to make a reverse movement. After the permission, the locomotive as the front of the train again, heading east. Now the westward movement can be as tiny as shoving back to get a pin (get slack in the couplers), or a long shoving movement into a siding or yard track… Now try figuring that one out without your head spinning!
Oh and the rear of the train can have the same thing happen too… Confused yet?? :slight_smile:

#10

@Craig. I had to read it twice, but I get it :slight_smile:

TonyWalsham said:
Why don't you run the same cable for everything and set the default start up direction of the loco you want to run backwards in the consist?
Tony, please clarify. My throttle in the trail car is rail Boss which I believe is very similar in operation to your Beltrol. Pehaps you assumed I am running an ESC that supports consisting. I am not. The railboss will allow me to program polarity, but I think a physical switch would be simpler.

My trail car has an Aristo style Female plug on one end only - the Front. It has bi-color LED’s on each end to indicate which direction the throttle is set to.

#11

I assumed you had ESC’s in each loco.

#12
TonyWalsham said:
I assumed you had ESC's in each loco.
No problem. That would make things simpler. I don't have this issue with my Aristo units pulling a similarly equipped trail car. So I guess they got it right.
#13
Jon Radder said:
@Craig. I had to read it twice, but I get it :)
Well if you understand it, you understand the rule better then some railroaders and dispatchers. The dispatchers will sometimes give you 'permission to make a reverse move' and you don't really need it. One of the Seattle Terminal dispatchers is really really anal about the rules, but he understands them quite well. So I call him up and ask for a reverse move. He says you don't need one. I reply back, yes "XXX, I do. I entered the block heading west, pinned back east, and now I need to pull back west again." He replies "Oh..." Long Pause, and then he gives me the permission. It was quite funny because I understood the rule and had to chew him out on the radio, instead of the normal him chewing out all the crews... :) Now back to the regularly scheduled program. ;)
#14

Craig, Maybe I am over simplifying, but doesn’t it boil down to this…

Once you call and get permission for a reverse move, the front of the train changes to the direction of travel. To go back the other way you need to call for permission again, and when you get it, the front of the train changes to the new direction of travel.

Our local short-line (and my railroad) does not operate by such complicated rules. Once they get permission in a block they can do whatever they want within it. No other trains are allowed into the block until they clear. And seeing as there is only a couple of trains operated per day over about 100 miles of track they rarely come close to each other.

#15
Jon Radder said:
Craig, Maybe I am over simplifying, but doesn't it boil down to this...

Once you call and get permission for a reverse move, the front of the train changes to the direction of travel. To go back the other way you need to call for permission again, and when you get it, the front of the train changes to the new direction of travel.

Our local short-line (and my railroad) does not operate by such complicated rules. Once they get permission in a block they can do whatever they want within it. No other trains are allowed into the block until they clear. And seeing as there is only a couple of trains operated per day over about 100 miles of track they rarely come close to each other.


Over simplified, but complicated. The reverse movement on happens in a controlled block that has independently controlled crossovers. 99% of crossovers don’t have this ability. What this does is it allows a dispatcher to pre-line the crossovers, while another train is still in the block. These blocks are huge, 1000’ at least. Anyway, each crossover is individually controlled, and at each, there is a bond for the signal system. So when you move past the bond, it lights up on the dispatchers screen as you having left that section of the block (think of it as multiple blocks within a single block. I know it’s complicated). If you move back into that ‘block’ that you cleared, it in effect becomes like running a red block, because after you cleared the dispatcher theoretically could have already lined someone else up. And this has happened in real life, hence the creation of the reverse movement rule. I’ll have to draw up a picture to explain…
Here’s the rule out of the GCOR. 6.4.2A is what I’m talking about.
"6.4 Reverse Movements
Make Reverse movements on nay main track, controlled siding, or on any track where a block system is in effect at restricted speed and only within the limits a train has authority to occupy the track.
6.4.1 Permission For Reverse Movements
Obtain permission from the train dispatcher or control operator before making a reverse movement, unless the movement is within the same signaled block.
When a train or engine is advised that working limits have been established behind their train, obtain permission from the employee in charge to make any reverse movements, including within the same signaled block.
6.4.2 Movements Within Control Points of Interlockings
A. Control Points or Manual Interlockings
Except when in track and time, if movement stops while the trailing end is between the outer opposing absolute signals of a control point or manual interlocking, the movement must not change direction without permission from the control operator.
B. Automatic Interlockings
At an automatic interlocking, the movement may change direction within the limits of the interlocking if it continuously occupies at least one car length of the limits.

What was funny was when I went back to Kansas City for engineer school the instructors told us specifically. You don’t need to learn this rule, as it only applies to the Chicago area. All of us Seattle guys spoke up and said nope it doesn’t. They couldn’t even explain the rule to us, we had to explain why and how them…

Clear as mud? Boy I sure got this thread off topic fast. :slight_smile:

Craig

#16

Craig Townsend said:
Boy I sure got this thread off topic fast. :slight_smile: Craig

No problem Craig. I think it’s relevant and even if I didn’t, who cares :slight_smile: In the interest of getting running sooner, railroad management discussed the options and made an executive decision about operations. When M-10 and M-11 are M/U’ed with Shorty the HEP car, the locomotives will be oriented “elephant style” with the F end leading. Also, whenever possible, M-10 will be the lead engine followed by M-11. In response the electric shop crew made up a straight though M/U cable…

(http://lsc.cvsry.com/Post3/M-11-14.JPG)

[Sorry about the cross-post on the cable - but it makes sense to be mentioned in both threads ]

#17

Jon,

I guess I don’t understand your problem. All of my Aristo diesasals are wired straight through, and it doesn’t matter whether I run them elephant style or a cab on each end of the consist.

I’ve even had 4 diesasals, 3 Dash 9s and an SD-45 MU’d together, with the locos in various positions within the consist, facing this way or that, like the 1:1 guys do, with nary a problem.

Is one of your Aristos wired backwards?

Happens.

#18

Steve Featherkile said:
Jon, I guess I don’t understand your problem. All of my Aristo diesasals are wired straight through, and it doesn’t matter whether I run them elephant style or a cab on each end of the consist. I’ve even had 4 diesasals, 3 Dash 9s and an SD-45 MU’d together, with the locos in various positions within the consist, facing this way or that, like the 1:1 guys do, with nary a problem. Is one of your Aristos wired backwards? Happens.

For starters I was wrong when I said I needed a “Straight-Through” cable. The one I made did the same thing as all my others. I have no problems with Aristo stuff. All my Aristo locos M/U together just fine. and nothing is backwards. It’s when I started wiring up non-Aristo locos using the same plug system that I ran into the snag because in the loco I followed COLOR from end, to end, not the individual wires like a bus. “Straight-Through”, as in a modular telephone cable, actually is a swap of positions from end-to end. We are talking about keyed connectors here. This is how all of my Aristo M/U cables are wired…

(http://lsc.cvsry.com/Post3/MUPlugs.jpg)

Note that when you put colors on the wires with reference to the keyway, the M/U cable is actually a swap from end-to-end even though when laid out straight the wires do not cross. Because I wired my locos wrong from end to end, I need a special M/U cable that actually crosses the wires to make them work. Also note that internally, Aristo locos are wired just like the MU cable in my diagram. This must be done so that all locos run the same direction when M/Ued together regardless of which way they face. BTW - When a single M-F pair is connected together, they are made so color runs across the connection. It’s when you make same gender cables that things must get turned around in order to be straight. Clear as mud ??? Now you know whey I am so confused by this :slight_smile:

#19

As far as I am concerned, electricity is done by smoke and mirrors, along with arcane incantations during a full moon. All I know is that it doesn’t seem to matter which way any locomotive (Aristo) is facing in the consist, things work well.

Pardon my frequent edits, I have a finger in a splint, and typing with it really sucks.

#20

To enable correct direction of running no matter which way they are hooked up to a trail car control. the wiring must always be key to key. Assuming of course the key wire is always the same polarity.

The swap over to suit separate truck motors that are mounted back to back in a loco should take place internally after the through cables are joined. This keeps the motor blocks running the same direction no matter which way the loco is oriented in the consist. http://rcs-rc.com/PDF/Acessories/Installation-kits/BIK-USA.pdf