Topics

Offset Rail Gapping

 

Greetings,
I've read, and been told, to offset the rail gaps between power districts. What is the science behind this and do we do that everywhere (for example in a reversing loop)?
Thanks,
Michael

Don Vollrath
 

It’s hearsay BS. No science behind it. Never seen a case where staggered gaps are required when other recommended practices are Being followed. Put isolating gaps opposite each other. Fill the gaps so they cannot close by rail movement.
DonV

whmvd
 

Michael,

I've read it too, and have followed several threads in various forums on this subject. I have never found an explanation for the practice that made sense to me, but people can get almost religious on this topic, so prepare for heated argument!

Wouter


On Sun, 22 Mar 2020 at 02:18, Michael Boyle <boyle10017@...> wrote:
Greetings,
I've read, and been told, to offset the rail gaps between power districts. What is the science behind this and do we do that everywhere (for example in a reversing loop)?
Thanks,
Michael

Jerry Michels
 

Michael, As far as I know, it is a way to avoid having a weak point where track could shift/kink out of alignment, especially on curves.  If used at all, the offset can be small.  If your track is properly installed and securely glued down, I do not think on offset is needed.  Consider that in almost every situation, when track is attached to a turnout the joints are not offset.  That being said, we have not found a problem having an offset with DCC.  We have some old-school members who insisted on having offsets, but in truth have suffered no ill effects either way.

Jerry Michels
Amarillo Railroad Museum

PennsyNut
 

The only place where offsetting might be warranted is in curves where you do not solder. The better way is to solder all rails in a curve. In fact, even turnouts in a curve should be soldered to the track next to them. But as has been stated above, staggered joints don't really make a lot of sense. Just MHO.
Morgan Bilbo, about one year with very basic DCC

dsabourne
 

This is a real world application ... where you never have joints in rails parallel to each other.  Not a practice required in model railroading.

-David

dsabourne
 

This is a real world application ... where you never have joints in rails parallel to each other.  Not a practice required in model railroading.

-David

mgj21932
 

David,
Now that answer makes sense.
Bill D

On Monday, March 23, 2020, 11:18:20 AM EDT, dsabourne via Groups.Io <dsabourne@...> wrote:


This is a real world application ... where you never have joints in rails parallel to each other.  Not a practice required in model railroading.

-David

prandn
 

RealWorldApplication ... joints in rails are ALWAYS* parallel to each other, a practice also required in model railroading.... 🙃

Now the staggering of joints is a completely different subject......

* Exception: when a “ sun-kink “ or derailment or some other phenomenon has caused the rails to become unparallel.....

loren martell
Aloha, OR 97007

thomasmclae
 

the reason for gaping both rails is to prevent current/power/signals from one block to another.
There is momentary shorts between blocks as metal wheels (Or Locos) cross the gaps.
These are usually handled fine, but offset gaps extend the short times for Locos and lit coaches/cabooses.
The only reason to stagger gaps is mechanical, and if you need to do this, your technique needs to be revised.
Thomas
DeSoto, TX

John
 

I was taught to slide one rail on flex track halfway onto the next piece on a curve to maintain the curve without parallel cuts to avoid kinks. I solder my joints and never gap on a curved section. Is this wrong? It seems like the new thinking is to join the two pieces with joints across from each other but soldering the joints while they are straight and then bending them to the radius you want. Doesn’t my way stabilize the radius and prevent kinks better?

John Melvin
 

Nothing wrong with this technique. It does what you state about stabilizing the track on curves. My railroad teachers from 70 years ago to present have taught me the same but also taught me that rail gaps should always be parallel at any change in electrical status, ie., ladder tracks in yards, engine storage tracks, mainline blocks, signal detection blocks, and moving from one booster region to another booster region, etc.

John
El Paso

In a message dated 3/25/2020 11:21:32 Mountain Standard Time, jjc3382@... writes:

I was taught to slide one rail on flex track halfway onto the next piece on a curve to maintain the curve without parallel cuts to avoid kinks. I solder my joints and never gap on a curved section. Is this wrong? It seems like the new thinking is to join the two pieces with joints across from each other but soldering the joints while they are straight and then bending them to the radius you want. Doesn’t my way stabilize the radius and prevent kinks better?

Jerry Michels
 

There is momentary shorts between blocks as metal wheels (Or Locos) cross the gaps.  

Is this true?  If the polarity and phase is the same for two blocks there should not be any shorts in my opinion.  If this was so, a train with all metal wheels would cause a large number of shorts to occur, and if a train stopped with a set of metal wheels bridging two blocks, the short would be constant.  I have not seen this.

Jerry Michels

Tim
 

I wonder about this fascination with gap locations. If you're using an autoreverser it will detect the short when when a wheel hits the first gap, flip the polarity, and everything will be fine. As far as wheels connecting power districts (or track circuit blocks) that will happen as long as the wheelbase of the loco straddles the gap (assuming all wheel pick-up). The gap locations don't make any difference (within reason). Steam locos with pick-up on one side of the loco and the opposite side of the tender will pick up from both sides of the gaps. This is why boosters are bonded. Trying to space the gap so that the lead wheel on the loco hits one gap at the same time as the lead wheel on the tender hits the opposite gap can only work for one type of loco moving in one direction.

Having the gap distance longer than the locomotive should probably be avoided, but shouldn't really cause any problem. See steam loco example above. :)

Tim Rumph
Lancaster, SC

john
 


Gentlemen,

The only place a short should occur is at a reverse loop or at a "Y. It doesn't matter if the polarities are reversed or not because your reverser, your PM42, or separate booster will make them the same almost instantly when they sense a short. It doesn't matter if the gaps are directly across from each other because when the wheels touch either rail with the reverse polarity, you reversers will correct both rails.

I have noticed that when engines cross a gap between power blocks, especially reverse loops there is sometimes and miniscule spark. No, I am not crazy but it has to be Black Out Dark to see it. 

I have see a decrease in jerks and starts over gaps when I fill in the gap with plastic. It also allows the gaps to be much smaller and keeps the rails from creeping and shorting together. Our layout is in a basement but rails still expand and contract down there. 

Keep you wires in a twist and your fun in a bunch.
jd
 

On Thursday, March 26, 2020, 10:48:34 AM EDT, Tim <tarumph@...> wrote:


I wonder about this fascination with gap locations. If you're using an autoreverser it will detect the short when when a wheel hits the first gap, flip the polarity, and everything will be fine. As far as wheels connecting power districts (or track circuit blocks) that will happen as long as the wheelbase of the loco straddles the gap (assuming all wheel pick-up). The gap locations don't make any difference (within reason). Steam locos with pick-up on one side of the loco and the opposite side of the tender will pick up from both sides of the gaps. This is why boosters are bonded. Trying to space the gap so that the lead wheel on the loco hits one gap at the same time as the lead wheel on the tender hits the opposite gap can only work for one type of loco moving in one direction.

Having the gap distance longer than the locomotive should probably be avoided, but shouldn't really cause any problem. See steam loco example above. :)

Tim Rumph
Lancaster, SC

wirefordcc
 

In this case, short means, makes a connection.  If the polarity of the two sections are the same, no shutdown of a booster or electronic circuit breaker should occur.

Allan Gartner
Wiring For DCC

Michael Maioriello
 

What gauge are you using, also what system do you use. I uses Lenz system 3.6 and must use circuit breakers. The science behind this is that LENZ Invented that’s out there and smart people ran with free technology. I am not up-to date on the newer systems to pick from. Good Luck!

On Sat, Mar 21, 2020 at 10:18 PM Michael Boyle <boyle10017@...> wrote:
Greetings,
I've read, and been told, to offset the rail gaps between power districts. What is the science behind this and do we do that everywhere (for example in a reversing loop)?
Thanks,
Michael