Large Scale Central

Large Scale Track Specifications

I am looking to fill in the part between the rails of some of my track, and want to know how much gap between the rails and the piece to leave, or more specifically the recommended distance between the wheels on the same axle. Where would I find this specification?

Found this. https://www.elmassian.com/index.php?option=com_content&view=article&id=85&Itemid=110

(https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

Nicolas,

As much as many on here will Poo Poo the NMRA, their data is almost spot on for the G1MRA which was around long before the NMRA took interest in large scale. I am not sure of Greg’s data, but I would bet it is going to be within a few thousandths of NMRA.

https://www.nmra.org/index-nmra-standards-and-recommended-practices is all the standards and recommended practices that will also answer all your questions.

Bob C.

I have G1MRA and NEM/MOROP on that page also.

Actually, (which may start an argument) when the NMRA revised their standards last time for G, they basically took G1MRA, but added some “slop” in a few places, which appears to me to placate some of the manufacturers who have for a long time used narrower back to back, thick flanges, deep flanges etc. I understand how adding the slop can make things more reliable, but in a toy train way, thus needing outsiize flanges, and flange bearing frogs.

I believe I state as much on my standards pages.

I follow the NMRA standards, but keep the tolerances ± tighter than the limits… basically G1MRA…

Greg

Bob, it is. We built the NMRA standards largely on the G1MRA standards, with notable exceptions for flange depth and wheel tread width. The G1MRA’s maximum flange depth is 2mm. The upshot of discussions among the standards committee and manufacturers was that this depth was too shallow for reliable operation outdoors. (A sentiment echoed on Greg’s page.) We went instead with a 3mm maximum flange depth, which seemed to curry a bit more favor with the manufacturers. It’s still smaller than some (notably LGB–the 800-pound gorilla in terms of equipment being run outdoors), but some other manufacturers have adjusted their wheel profiles to better match these standards since they were approved 8 years ago. Whether that was conscious or coincidence, who knows.

To Nicolas’s question about flangeway clearances, I’d shoot for around 1/8" (0.125") in the case of flangeways for grade crossings or filled-in spaces between the rails. In this environment, you’re not trying to prevent a derailment at a frog, so you can give just a little more wiggle room than what the standards call for. The standard for flangeways for switches is 0.120" (G1MRA) or 0.116" (NMRA). The “recommended” back-to-back spacing for wheels is 1.575", though this often gets narrowed to as little as 1.560." The maximum distance between guard rails for both G1MRA and NMRA is 1.555".

Greg, might I point out some minor corrections to your page? First, your links to the NMRA standards are no longer accurate. The NMRA re-did their page not too long ago, moving the standards. (screwed my bookmarks up, too.) Here’s the link to all their standards:

https://nmra.org/index-nmra-standards-and-recommended-practices

Also, in your discussions of the NMRA standards on your page, the values you quote under the NMRA’s Hi-Rail standards for flange depth and flange thickness are incorrect. It should read:

Flange thickness: Target 0.074", +0.002", -0.014"

Flange depth: 0.118" maximum depth. (3mm)

Lastly, you seem to have coded your page to not allow “copy-paste” operations for copyright reasons (valid reasoning), yet you have web addresses listed further down which require the reader to copy and paste in order to follow them. Can you convert those to links?

Later,

K

thanks Kevin, will fix them… although only the S4.3 link was broken out of all those links on the page.

The links that were not live were basically notes to me, and if you had looked carefully, they were already duplicated in the main text.

I’ll look at the high rail specs that you mentioned… I’ve got some more revisions to the page and I’m out of pocket at the moment.

Greg

I realized after browsing trying to find the # i needed that I could just measure the guard rails on my turnouts. If the cars fit through there then they would fit through the space I am filling in. Just like those guard rails, I am going to make then bend in (away from the rails) to act as a guide. Measuring I found it to be 38mm on average so that is what I am going to go with.

As a Canadian, I find dealing inches at anything less then some of the common measurements (1/8, 1/16, etc…) to be too cumbersome and switch to millimeters. 38 millimeters is easier to measure and remember then 1.496 inches. The turnouts ranged from 37.4 to 38.1 mm for the distance. I took a few samples from about 5 different turnouts to average out the distance.

The NMRA specs are in both inches and metric. use s.2 and s3.2 is my advice… links there on my page.

Greg

When I built my switch, I set the frog guard rail’s gap at 1/8th an inch. That worked fine for the life of the switch. Since you are doing a longer section, a bit more slop would probably be preferred. You really don’t want the inside of the flanges dragging on your insert for any distance. Also, you don’t want the gap so tight that you can’t dig out the debris that finds its way into the gap.

Looks like my measurement was close. I can bring it in to 39 mm according to the S3.2 page.

where i made grade crossings, train stations or other things, that call for filling in, i just took the distance to the guard rails of LGB turnouts PLUS the thickness of these guardrails. so the gaps are about 6mm.

note, that on turnouts you got guardrails only on one side at any given spot. (if we ignore the frog).

i prefer to leave a bit of “slack” for not well adjusted axles, or cheap cars with thick wheels.

Thanks Korm. I was thinking the same thing. On my turn outs there were 2 guard rails. I didn’t feel the need to add any extra as you did since the cars need to make it through the turnouts.

One thing to consider is what manufactures have done for their grade crossing product. For example, Aristo’s Re-railer illustrated below.

Aristo Re-railer

-Ted

I am going to be filling in the track areas near the doors to my shed to reduce the size of the gap there. Trying to cut the doors so they fit into the track didn’t work out quite as well. By filling in all the track, and raising the areas out side the entire area will be mostly flat with only tiny gaps for for the wheels. I will be also slowing the middle part downward so if water hits it it runs away from the door.

Kevin, et al,

Based on an experience with an AMS car with more fine scale flanges I tend to believe that the articulation of the truck has far more to do with reliability than flange depth. I have an AMS tank car that would continuously derail on the club layout at one spot where the track had a slight dip on one side. After spending an hour or so watching the train pass and watching the car derail because the truck was too rigid to allow the wheel to follow the rail I determined that I needed to change the springs in the truck to allow more freedom. A call to Accucraft yielded a set of softer springs for the lighter flat car. After installing the lighter springs, the car now tracks perfectly as the truck can articulate and follow the rail.

I now modify all my Bachmann/USA Trains/LGB rigid trucks to allow them to articulate and have removed nearly 100% of my derailment problems caused by less than concrete slab perfect track work. There is no doubt that a ‘pizza cutter’ wheel flange will accomplish a lot in that arena, but the prototype railroads don’t use articulating trucks for no reason, just look at a seldom used siding when the local switcher does his business. And I do still purchase Bachmann 31mm wheel sets, they are the best deal in town (especially if you purchase case lots - 6 cards to a case).

No doubt, Bob, but few trucks are articulated, and those which are sprung seldom have soft-enough springs to ensure proper articulation in our scale. With soft enough springs, even completely scale flanges will stay on the tracks. I’ve got an EBT caboose that rides on a set of Rich Yoder’s gorgeous trucks. The flanges on those are darned near 100% scale. Stock, the springs are far too stiff for the articulation to work, and the caboose jumped at the slightest provocation on my railroad. I replaced the stock springs with much softer ones which allow proper articulation, and the caboose rides very well. It’s still not nearly as tolerant of debris on the track, though, so larger-than-prototype flanges do still have their advantages even with articulation.

Later,

K

Isn’t an 1/8" twig on the rails over 6 scale inches high?

Until we get scale debris, it will be difficult to use scale flanges I would wager. (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Greg

Greg Elmassian said:

Isn’t an 1/8" twig on the rails over 6 scale inches high?

Until we get scale debris, it will be difficult to use scale flanges I would wager. (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)

Greg

Greg,

I have to agree with that assessment. The height of the flanges on my 1/8th scale rolling stock trucks is .150. One-eight of that is just under .019. I can chop an 1/8"twig easily, but .25" or more can be problematic! (even with this scale).

EDIT: My mistake on the flange height of 1/8th scale: The height should be 0.180 or just under .023. The flange WIDTH is .150 or just under .019.

The other place scale flanges won’t do is unsprung locomotives. The Aristo 3 axle block is famous for this, there is no up and down movement, only twisting along the long axis of the block.

Go up a grade and watch the leading axle come off the rails. Flanges are the only thing keeping the tread over the rail head and not derailing.

Greg