Has anyone heard of the recommendation to stagger rail joints on a DCC layout for electrical reasons? I recently read (I can't find the reference) of a recommendation to stagger rail joints by at least 1/8" on DCC layouts to reduce interference (?). Is there any basis for doing this? I've heard of staggering rail joints so they are not directly opposite to each other for mechanical reasons.
Any information would be greatly appreciated.
Bob
Some do, some don't. Some stagger by more than 1/8 inch but never saw any discussion on interference. I assume interference of the DCC signal.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I've been in model railroading for more than 40 years and I haven't heard of it. I am also a retired Electronics Technician. No valid reason to stagger track joints for electrical reasons. I do solder all of my rail joints and then cut any gaps I need with a cut-off disk in a motor tool.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Recall discussion on the topic of staggered joints as regards reversing loops. forget the reason but I staggered my two reversing loops .
I can't think of a single valid electrical reason to stagger your gaps, but obviously there are several good mechanical reasons to do so. The only POSSIBLE thing I could even remotely think of involving electrical gaps might be for some sort of crosstalk / interference and that angle is already blown so far out of the water as to be situated in the Sahara desert, notionally-speaking. You already have so many other possibilities for "interference" that any added potential for interference from an opposing rail is completely miniscule and quite infinitesimal. Whoever said that most likely did not understand much about electricity, DCC, or EMI/EMF.
My
John
RFinch Has anyone heard of the recommendation to stagger rail joints on a DCC layout for electrical reasons? I recently read (I can't find the reference) of a recommendation to stagger rail joints by at least 1/8" on DCC layouts to reduce interference (?). Is there any basis for doing this? I've heard of staggering rail joints so they are not directly opposite to each other for mechanical reasons.
The only electrical reason for staggering the insulated rail joiners or gaps is at the ends of reversing loops when using an autoreverser. The autoreverser senses a short when a metal wheel spans the gap to/from the reversing section, and the polarities are not aligned. The autoreverser then changes the polarity of the reversing section to match before the DCC system circuit breaker can trip. If both rail gaps at either end of the reversing section are spanned by metal wheels at exactly the same time, the autoreverser might get confused. Hence the recommendation to stagger the gaps by 1/8" to prevent the event from happening in both rails simultaneously.
Fred W
Some autoreversers recommend staggered gaps, others want them parallel. For other gaps, there's no electrical reason to stagger them. My divisions between sections of my PM42 circuit breaker have the gaps directly across from one another, and there are no issues with trains moving through, even at crawl speeds. Unless otherwise directed in a particular product's manual, there is no reason to stagger the gaps.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
DCC specialties recommends staggering the insulated rail joints when setting up power districts and reverse loops using the PSX and OG breakers. According to them is that there is less chance of arching on the wheels and axle bearings. Also a single wheel set will not be able to bridge a gap if one section is shorted. As far as I know this is the only reason to stagger joints beside prototype fidelity.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
I'm into NTRAK modular railroading. Can't stagger the joints on modules because the ends are straight. Been in a few large layouts including one that filled a 50,000sq ft room. Never had any problems. I don't stagger my reverse loop rail joints either. I do stagger my joints a little on curves but that's because they seem to hold the radius better when laying track.
This sounds like another one of those Urban Model Railroad Myths. ;-)
We never staggered the joints in DC - and in the early years of changing over from DC to DCC there was no mention of staggering the gaps!
Now the Reversers and some companies - suggested staggering the gaps - and these were the more EXPENSIVE units
YET !
MRCs basic AutoReverser never recommended a staggered joint - and this was as basic a unit there was - so if there was a problem - wouldn't it be the CHEAPEST manufactured unit that would fail if this staggered joint be a PROBLEM???
I have several on my current layout and have NEVER staggered any joints and now have 10 years of Operations twice a month (pretty close to 700 hours running time) and have had no problems!
I also have the Digitrax AR1 (reversers) and PM42s set up as auto reversers - and ALL of my JOINTS are straight across from each other!
I run a lot of Metal Wheel cars and this make NO DIFFERENCE in the Reversing Action!
Once the first wheel trips the Reverser - there is NO MORE tripping as both sides are now the SAME POLARITY !
I would chalk this one up to another URBAN MRR Myth BUSTED ! ;-)
BOB H - Clarion, PA
locoi1sa DCC specialties recommends staggering the insulated rail joints when setting up power districts and reverse loops using the PSX and OG breakers. According to them is that there is less chance of arching on the wheels and axle bearings. Also a single wheel set will not be able to bridge a gap if one section is shorted. As far as I know this is the only reason to stagger joints beside prototype fidelity. Pete
Pete is correct. It was in the DCC Specialties' instructions for their PSX-AR series auto reversers in the section "Important Installation Tips" that they said,"When setting up gaps for reverse sections, we recommended that the gaps be staggered about 1/8". Perfectly aligned gaps may reduce the current needed for the PSX-AR to reverse properly."
I must have been half asleep when I read this, because I read it as joints, not gaps. Not having the insulated gaps in register makes perfect sense in this context.
I want to thank everyone for their input and especially Pete for jogging my memory for where I read the statement about "joints". I'm just getting into DCC so please forgive my ignorance.
Thanks again to everyone,
PSXAR needs to have power on one rail because that's how it gets its own power. There is no outside power source for the board. Wheel trips at first gap and phase swaps. Power stays on the other rail long enough to make it happen.
mfm37 PSXAR needs to have power on one rail because that's how it gets its own power. There is no outside power source for the board. Wheel trips at first gap and phase swaps. Power stays on the other rail long enough to make it happen.
My AR1's are also rail powered, and IIRC the instructions make no mention of staggered gaps. And even if staggered gaps were mentioned, I didn't bother to stagger mine and my AR1's still work reliably and dependably every time.
Stevert My AR1's are also rail powered, and IIRC the instructions make no mention of staggered gaps. And even if staggered gaps were mentioned, I didn't bother to stagger mine and my AR1's still work reliably and dependably every time.
My AR1's also work fine without staggered gaps. My PM42's do as well with their separate power supply. My old MRC reverser worked as well with out staggering. They use relays. Relays that will be energized to hold one state. When the short occurs and power drops instantaneously, the relay is de-energized, points move, voila- phase is corrected.
My last post was about PSXAR's. They are solid state. No moving parts.
I dount the PSX's are powered fromt he output side, that makes no sense whatsoever. They probably recommend the staggared gaps because of the electronic switching. Unlike a relay which is changing both terminals at the same time, there is a small but definite lag as the microcontroller on the PSX turns off one set of transistors and turns on another. It's fast, so there is no perceiptible drop out for the loco runnign through the loop, but it's not instnat (neither are relays, there is a time lag for the armature to move in a relay). The stagger give enough time for the electronics to complete switching without potentially feeding back via the decoder.
Pure speculation simply based on knowledge of how electronic things work. I don;t have a PSX device nor have I seen one to analyze the circuit, and even then I'd have to see the code in the microcontroller to really see how it works, and that is not likely.
It is recommended by DCC specialties. Not absolutely necessary though. Another manufacture that recommends a staggered insulated section is Lenz. In talking to a Lenz tech at a train show is that there is a possibility of one axle/ wheel set to bridge an insulated gap when one district is already shorted. This in turn will trip the next section or in fact back feed into the shorted district. As an example train A runs a closed switch and shorts that district(A). Train B is coming out of the shorted district but the locomotive is on the next district(B). One wheel set of the train bridges both gaps between districts. Five amps of booster power from district B now flows through both wheels into the shorted district A. Either both will shut down or something worse like a fried circuit. A staggered gap of 1/8 to 1/4 inch is the recommendation. Our club uses this recommendation in our permanent and our modular rail roads. I also stagger the insulated joints on my home layout also. I do not use joiners with my hand laid track and my insulated gaps are just .010 styrene with plastic joint bars glued to each side. It does not hurt to stagger the joints.
[quote user="cmrproducts"]Now the Reversers and some companies - suggested staggering the gaps - and these were the more EXPENSIVE units
MRCs basic AutoReverser never recommended a staggered joint - and this was as basic a unit there was - so if there was a problem - wouldn't it be the CHEAPEST manufactured unit that would fail if this staggered joint be a PROBLEM???[quote] No, that is faulty reasoning.
[quote user="Texas Zepher"]
No, that is faulty reasoning.
In your Opinion!
While others are trying to make a point that a Staggered Joint is the better way or needed to make these Reversers work!
Which it is not.
If the Staggered Joints - were needed - then ALL Manufacturers would require them - from the least expensive (cheaply manufactured) to the most expensive units.
This is where these Urban MRR Myths - begin and some are bound and determined to keep them going!
Which only confuses the NUBEs - it is no wonder so many leave the hobby - can't get a straight answer!
YMMV
I can think of one good reason not to.
If you have a reverse section that is NOT longer than the longest train you will run through it, then straight across gaps are better. I have just such a section, a crossover on an oval. By staggering the gaps, you create a longer "conflict zone" rather than a single "conflict point" at each end. Thus, the chances that you will be bridging gaps at both ends simultaneously increases.
I have an alternate plan for making my reversing section longer, but I have a DCC Specialties solid-state auto-reverser, and it responds so quickly that I never have a problem as long as I keep the train moving at a reasonable speed.
It takes an iron man to play with a toy iron horse.
cmrproductsIf the Staggered Joints - were needed - then ALL Manufacturers would require them - from the least expensive (cheaply manufactured) to the most expensive units.
Obviously not reading or understanding what I am typing!
I stated
IF STAGGERED JOINTS were NEEDED
then all manufacturers would state so!
I DID NOT state that they HAD TO USE THEM.
The vast majority do NOT use them - SO - appeariently it is NOT a requirement!
Some replies on here were trying to make the POINT - that the STAGGERED JOINT was some how BETTER - which it is NOT!
Texas Zepher cmrproducts: If the Staggered Joints - were needed - then ALL Manufacturers would require them - from the least expensive (cheaply manufactured) to the most expensive units. So If I design a really expensive gizmo to operate according to spec A, it should behave the same way as a cheap gizmo designed to spec B? I think all those people with expensive English cars with steering wheels on the right side would not agree the steering wheels should be on left side just because cheap American cars are that way.
cmrproducts: If the Staggered Joints - were needed - then ALL Manufacturers would require them - from the least expensive (cheaply manufactured) to the most expensive units.
So If I design a really expensive gizmo to operate according to spec A, it should behave the same way as a cheap gizmo designed to spec B? I think all those people with expensive English cars with steering wheels on the right side would not agree the steering wheels should be on left side just because cheap American cars are that way.
cmrproducts IF STAGGERED JOINTS were NEEDED then all manufacturers would state so! I DID NOT state that they HAD TO USE THEM. The vast majority do NOT use them - SO - appeariently it is NOT a requirement! Some replies on here were trying to make the POINT - that the STAGGERED JOINT was some how BETTER - which it is NOT! BOB H - Clarion, PA
You are the one confusing "need" or "required" with "better". Just because staggered joints are not required in the situations you have experienced does not mean that non-staggered joints are "better". There are sound mechanical and electrical reasons for using staggered joints or gaps, which have already been discussed.
The fact that you have not experienced any problems with non-staggered gaps does not make the reasons go away. Reality is that unless extraordinary attention was paid during construction using flex track, it is highly unlikely that the gaps are aligned well enough so that wheels would normally bridge both gaps within the same 20 milliseconds. The recommendation was to stagger the gaps by a whole 1/8" inch to make sure the simultaneous bridging of gaps doesn't occur.
Even if wheels do bridge the gaps simultaneously, there is no guarantee disaster will occur. The potential exists for the auto-reverser not to work properly when both gaps are bridged within the same 20 milliseconds. Doesn't say it won't work correctly, just that it might not. So the odds are already stacked in your favor, regardless of whether you stagger gaps or not. Staggering the gaps just increases the already high probability slightly more in your favor.
Mechanically, staggering gaps and joints on curves makes it easier to avoid kinks and out-of-gauge spots. Again, one can certainly make aligned gaps and joints work. Staggering simply decreases the odds of problems.
my thoughts, your choices
Someone needs to derive a probability density function graph for visual appreciation of what we are talking about. Obviously, most of us get away with not staggering the gaps intentionally, but the fact is that we do really stagger them..just not enough to see without measuring. The closer we get the two gaps directly across transversely and the same distance from rail ends to rail ends, the higher the probability of getting a confounded reverser.
Crandell
Fred
We can argue for years on this topic and no one is going to convince the other of anything! ;-)
What it boils down to is THIS -
Follow the Manufacturers INSTRUCTIONS !
If you don't then you run the risk of the item NOT WORKING properly!
PERIOD - END OF DISCUSSION !
fwright Bob You are the one confusing "need" or "required" with "better". Just because staggered joints are not required in the situations you have experienced does not mean that non-staggered joints are "better". There are sound mechanical and electrical reasons for using staggered joints or gaps, which have already been discussed. The fact that you have not experienced any problems with non-staggered gaps does not make the reasons go away. Reality is that unless extraordinary attention was paid during construction using flex track, it is highly unlikely that the gaps are aligned well enough so that wheels would normally bridge both gaps within the same 20 milliseconds. The recommendation was to stagger the gaps by a whole 1/8" inch to make sure the simultaneous bridging of gaps doesn't occur. Even if wheels do bridge the gaps simultaneously, there is no guarantee disaster will occur. The potential exists for the auto-reverser not to work properly when both gaps are bridged within the same 20 milliseconds. Doesn't say it won't work correctly, just that it might not. So the odds are already stacked in your favor, regardless of whether you stagger gaps or not. Staggering the gaps just increases the already high probability slightly more in your favor. Mechanically, staggering gaps and joints on curves makes it easier to avoid kinks and out-of-gauge spots. Again, one can certainly make aligned gaps and joints work. Staggering simply decreases the odds of problems. my thoughts, your choices Fred W
Obviously some people have no idea what the difference is between a recommendation and a requirement is. It is Recommended to stagger the gaps between powered districts and reverse loops by some manufactures. It does not mean you have to do it!
My recommendation is that all of you guys give me all of your money. It does not mean you have to give me all your money!!! You can give the government the rest. Paying taxes is a requirement. Not a recommendation.
Get it now!
selector Someone needs to derive a probability density function graph for visual appreciation of what we are talking about. Obviously, most of us get away with not staggering the gaps intentionally, but the fact is that we do really stagger them..just not enough to see without measuring. The closer we get the two gaps directly across transversely and the same distance from rail ends to rail ends, the higher the probability of getting a confounded reverser. Crandell
So who's going to be the one to lay some track and cut gaps DIRECTLY across from one another to the tenth (.0001") and also build cars with metal wheels set precisely at the track gauge so they must track perfectly straight with no wobble side to side - so that it absolutely positively will cross the gaps at exactly the same time, and see if the reverser works.
Or just build a simulator - use a DPDT relay as the track gap, so both will switch at the same time, with an autoreverser feeding it - this might be more practical but the first one should be a great project for a precision machinist