Is flex track ever out of gauge?


Gdelmoro

Gdelmoro

Member
I just replaced a section of track that was problematic with a new piece of Code 100 Atlas Flex track. When the locomotive goes over it it derails. Seems that the space between the rails is too wide according to the NMRA gauge. Is it something I did installing the tracK? Or could it be a bad length?

In any case I need to rip it up again.
 
It would be extremely rare, and perhaps a problem with packaging more than a manufacturing defect. Or storage. Or handling.

Flex track is often designed to lighten the gauge a bit on curves. It stands to reason because the one rail slides, or in some cases, both rails slide. In order for them to slide, there must be a tolerance adjustment in the spikehead details. Even so, I have never found the rails more widely spaced on curves outside of the NMRA gauges than perhaps a fraction of a mm, not enough to derail anything except cars whose wheels are actually a fair bit tight on the same gauge.

More often than not, a derailment on a curve with carefully handled flex and on cars and locomotives whose wheels are NMRA RP25 compliant, and themselves in gauge, comes from rail-head heights not flush across from each other on a curve. What I mean is that most often it isn't so much a mismatch with gauges, wheel and rail, but a problem with keeping the rails at about the same height transversely from each other. Outside of super-elevation, the rails across from each other have to match if you were to place a straightedge along both rails. A dip in the outside rail makes all bets off, and it is especially bad with every new longish car or locomotive you get.

The NMRA gauge may show your flex is wide, but my point in all of this is: what is 'wide' with modern HO and typical tire widths and tolerances? You should be able to have as much as a full mm wide in some places, certainly on a tangent, and have almost no derailments ever. Curves are different, but the point where the gauge notch just fails to clear is not the point where you should be getting derailments. Half a mil outside of that, probably.

Do many items derail there, or just one or two? If so, consider widening their wheelsets about half a hair. T'will make a world of difference.
 
The gap between the ends, if too large, can be a problem. We have a couple on the club layout where, as wheels pass over them there is a really audible click. I have had the odd derailment at those. I put it down to causing a wheel to jump. The main problem though with any piece of straight metal, is that it's hard to get the last bit at the ends, to curve in the same manner as the rest , because the leverage to make it curve isn't there. That gets worse the tighter the curve. Generally it means that to eliminate that, it's necessary to sacrifice the end inch or more to get rid of the straight bit.

The other consideration is that you need to remove a few ties at each joint to get the track joiners on, replacing the ties, sans their spike head detail, so they can be slipped beneath individually, consequently loosing their alignment. As mentioned, and the greatest probable cause of derailments, is peaks or dips at the joint and the last couple of inches either side. I left a note on one like that, for the track supervisor, that had enough elevation on one side of a joint to raise a car up so it uncoupled.
 
Another thing that can change the gauge would be driving a nail too far and bending the ties, but that would narrow it.
Soldering might give problems if the rail gets too hot, which makes me wonder if it was laying in the sun at one point?
 
Another thing that can change the gauge would be driving a nail too far and bending the ties, but that would narrow it.
Click to expand...

There's a few of those on the club layout too. If excessive, wheels that may be gauged a bit wide, will ride up and off. Turnouts are highly susceptible to humps, twists and dips if they aren't adequately supported to keep a flat plane across them. One's that float can cause wheels to diverge across the frog.
 
In my case the NMRA Gauge slips off the rails inside making them just too wide. Guess I'll replace the section this weekend.
 
I had a recent issue with my BLI 2-8-0 shorting out on the staging loop. A week later I realized that sometimes the locomotive derailed at that spot on the track.

I had assumed that the track was flawless until I remembered that this locomotive is sensitive to track geometry. If it's much out of spec this locomotive has issues. The 18" minimum radius is absolute.

So I looked at the flex track and realized it was dog legged going into the curve on both ends of the curve. It had straightened out in between the straight track and the sectional track I used for the loop.

It's at the least accessible spot on my entire layout. I ended up sticking a puddy knife under the track and using a lot more glue this time.

The moral of the story is make sure the transitions between pieces of track are straight( or a continuous curve). Tight curves are tricky to get right with flex track.




Modeling the roaring 20's
President of the Lancaster Central Railroad
President of the Western Maryland Railway
 
Is it missing the little tabs that hold the track in place? What is underneath the piece of track?

Modeling the roaring 20's
President of the Lancaster Central Railroad
President of the Western Maryland Railway
 
As with anything mass-produced it is possible that this piece of flex track may simply be a manufacturing error. It happens. It is almost impossible to check each and every item. However...this is one reason when I built my current layout I elected to use Atlas and Shinohara sectional track on my curves. The flex track is limited to long straight runs, with curves limited to transition portions leading into curves. While some may recoil in horror at using sectionals, I find, as long as I check for expansion problems, derails are kept to a minimum!
 
trailrider said:
As with anything mass-produced it is possible that this piece of flex track may simply be a manufacturing error. It happens. It is almost impossible to check each and every item. However...this is one reason when I built my current layout I elected to use Atlas and Shinohara sectional track on my curves. The flex track is limited to long straight runs, with curves limited to transition portions leading into curves. While some may recoil in horror at using sectionals, I find, as long as I check for expansion problems, derails are kept to a minimum!
Click to expand...
I use flex track on visible mainline track because it looks better and it will be ballasted which holds it permanently in place. I soldier the joints on curves and keep them offset from each other.

I used about 75% sectional track in my staging area. It stays in place with minimal glueing and is easy to move when a better idea hits. Especially when I had to use 18" radius curves. Flex track naturally wants to straighten over time on tight curves.

I found alignment issues would pop up over time with flex track combined with the curved turnouts. I also have rerailing tracks to add new cars to the layout in the staging yard.

Modeling the roaring 20's
President of the Lancaster Central Railroad
President of the Western Maryland Railway
 
You must log in or register to reply here.



Back
Top