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Width of an NMRA Standards Gage

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Width of an NMRA Standards Gage
Posted by 7j43k on Saturday, August 7, 2021 11:44 AM

Yup.  "Gage".  That's how it's spelled on my NMRA standards gage.

Anyway.

In the topic "Yard Track Spacing and Radius...", there has been some discussion on how wide the Standards Gage is.

Mike said first that his was 2 3/16" wide.

I said that I felt differently--that it was 2 1/16" wide.  I just measured mine again (a MARK IVb) with a micrometer, and it is 2.063 wide.  That's 2 1/16".

 

That's an eighth of an inch difference!  For a GAGE!

 

Very curious, I thinks.  I just checked the NMRA Recommended Practice for this dimension, and got 2 X 1.10", or 2.20".  THIS is very close to the 2 3/16" reported by Mike and others.

And yet, I'm holding an official NMRA gage that says different.

At least online, it doesn't appear that NMRA keeps historical information about any dimension changes over time.

However, it so happens I have copies from Olden Times.  The dimension under discussion was shown as 2 X 1", or 2", in a 1959 copy of Standard S-8.

 

So, over time, we have a Standard Dimension changing, without notation in the Standards.  And/or the Recommended Practices.

 

To date, I've never used my various NMRA Standards Gages to check this dimension.

I'll note here that the current 2.2" matches the structure clearances noted in both Washington and Oregon railroad clearance standards from the fifties.

 

I post this topic to explain the differences reported in the other topic, and to reveal a certain fluidity in NMRA standards, generally undiscussed.  I should dig out my OLD NMRA gage, buy a new one, and build a display of "NMRA Gages over the years".

 

Ed

 

 

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Posted by mikeGTW on Saturday, August 7, 2021 11:54 AM

Ed

I guess I'm kind of behind the times  mine is a Mark II gage  and it is 2" wide

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Posted by 7j43k on Saturday, August 7, 2021 12:24 PM

mikeGTW

Ed

I guess I'm kind of behind the times  mine is a Mark II gage  and it is 2" wide

 

 

You're sitting on a FORTUNE, man.  DON'T loose that!

No.  Wait.  

Can I have it for my collection?

 

Ed

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Posted by RR_Mel on Saturday, August 7, 2021 12:25 PM

When I was building one of my camera cars I made a CAD drawing to scale of my NMRA Gage using my digital caliper.



It was very helpful with the design of the car.



I was able to keep the camera movement within the needed clearance of my tunnel portals.



Mel
 
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Posted by ATLANTIC CENTRAL on Saturday, August 7, 2021 12:41 PM

7j43k

Yup.  "Gage".  That's how it's spelled on my NMRA standards gage.

Anyway.

In the topic "Yard Track Spacing and Radius...", there has been some discussion on how wide the Standards Gage is.

Mike said first that his was 2 3/16" wide.

I said that I felt differently--that it was 2 1/16" wide.  I just measured mine again (a MARK IVb) with a micrometer, and it is 2.063 wide.  That's 2 1/16".

 

That's an eighth of an inch difference!  For a GAGE!

 

Very curious, I thinks.  I just checked the NMRA Recommended Practice for this dimension, and got 2 X 1.10", or 2.20".  THIS is very close to the 2 3/16" reported by Mike and others.

And yet, I'm holding an official NMRA gage that says different.

At least online, it doesn't appear that NMRA keeps historical information about any dimension changes over time.

However, it so happens I have copies from Olden Times.  The dimension under discussion was shown as 2 X 1", or 2", in a 1959 copy of Standard S-8.

 

So, over time, we have a Standard Dimension changing, without notation in the Standards.  And/or the Recommended Practices.

 

To date, I've never used my various NMRA Standards Gages to check this dimension.

I'll note here that the current 2.2" matches the structure clearances noted in both Washington and Oregon railroad clearance standards from the fifties.

 

I post this topic to explain the differences reported in the other topic, and to reveal a certain fluidity in NMRA standards, generally undiscussed.  I should dig out my OLD NMRA gage, buy a new one, and build a display of "NMRA Gages over the years".

 

Ed

 

 

 

My old one is smaller, one I just bought from the NMRA last year is bigger.

Sheldon

    

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Posted by mikeGTW on Saturday, August 7, 2021 1:05 PM

7j43k
You're sitting on a FORTUNE, man.  DON'T loose that! No.  Wait.   Can I have it for my collection?   Ed

 

I wish   $10 on evilbay

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Posted by Lastspikemike on Saturday, August 7, 2021 1:58 PM

Mine is a Mark V.

Measured with a Zona tools square.

Alyth Yard

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Posted by Pruitt on Saturday, August 7, 2021 2:09 PM

As equipment widths on the prototype has changed over the years, the NMRA has changed their standards gage as well. Some of the changes were done to reflect prototype changes, and some were done to reflect NMRA Standards changes. Equipment has gotten somewhat wider over the years. So has the gage.

So it isn't surprising that different variants of the gage have different dimensions (otherwise, why would there be different variants in the first place?).

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Posted by 7j43k on Saturday, August 7, 2021 2:31 PM

Mark,

 

Equipment has NOT gotten wider over the years.

In 1955, Plate B (the only one shown in my ORER) width was 10'-8".

In 2015, all Plates showed a maximum width of 10'-8".

 

I expect the widening of the gage was done for good and thoughtful reasons.  But it wasn't done because the prototype got wider.

 

Ed

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Posted by selector on Saturday, August 7, 2021 2:50 PM

I don't know, but my guess is that as longer rolling stock became more widely used, and modelers developed a robust market for large steamers, it became necessary for 'recommended' clearances to reflect a wider safety margin irrespective of actual prototype dimensions and practices.  A responsive governing body will listen to feedback and complaints about a protocol's or a device's deficiencies, and they'll make adjustments so that those things offer more utility to their constituency and membership.

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Posted by SeeYou190 on Saturday, August 7, 2021 3:10 PM

Mine is a Mark IV.

Does anyone have a link to the instructions for how to use it? I think that would be very helpful. I have a feeling some contributors are are not using the gage the same as others, or maybe we are talking about something the gage is not even intended to be used for.

I do not use my gage to check clearances. I use an 86 foot high cube boxcar for that. I space my tracks wider than NMRA recommendations for finger clearance.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by peahrens on Saturday, August 7, 2021 3:21 PM

ATLANTIC CENTRAL
My old one is smaller, one I just bought from the NMRA last year is bigger. Sheldon

That's what Hersheys and others do with candy bars.  A Snickers was 5 cents.  They made it bigger and charged 10 cents.  Then they made the 10 cent bar smaller again, etc.  Expect the next NMRA gage version to be smaller but cost the same, then a larger, more expensive version a few years after that, and so on.

Or, it's like fashion for (wearable) ties: wide ties are in, skinny ties are then in, then wide ties again, etc.Big Smile

Paul

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Posted by 7j43k on Saturday, August 7, 2021 3:24 PM

Here's the official directions:

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/rp-2_2019.07.07_typo_correctiontrack_gages.pdf

 

I see there are some videos on the subject, too.

 

Ed

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Posted by 7j43k on Saturday, August 7, 2021 3:33 PM

selector

I don't know, but my guess is that as longer rolling stock became more widely used, and modelers developed a robust market for large steamers, it became necessary for 'recommended' clearances to reflect a wider safety margin irrespective of actual prototype dimensions and practices.

 

Longer rolling stock isn't involved here, as we're talking about a gage that's designed for straight track.  It's the width, only.

Yup, there's a robust market for large steamers.  But I doubt that their overall width is significantly greater than "medium" ones.  That's a tougher one to nail down though.  I just paged through a diagram book for SP&S steam, and the railroad didn't list extreme widths.  They must have thought it unimportant.

 

Ed

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Posted by SeeYou190 on Saturday, August 7, 2021 3:35 PM

7j43k
Here's the official directions:

Thanks Ed.

It looks like what I thought was correct. The total width of the gage is not used for checking anything.

Am I missing something?

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by 7j43k on Saturday, August 7, 2021 4:03 PM

SeeYou190

 

 

It looks like what I thought was correct. The total width of the gage is not used for checking anything.

Am I missing something?

 

 

 

You use the "total width of the gage" to check for NMRA horizontal clearance on straight track.

Considering that the width of the MARK V gage mirrors almost exactly the required clearances in Washington and Oregon (and likely elsewhere), it's not totally useless. It's also good for having a place to put all the notches and bumps.

That funny little notch on the left is to check platforms.

Oh.  It turns out the MARK II Standards Gage was issued in the early sixties, to reflect the new RP25 flanges.  I doubt the MARK I was marked with a "I".  I MIGHT have one somewhere.  I MIGHT have lotsa things.  Somewhere.

Pretty sure I've got a MARK II.

Ed

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Posted by SeeYou190 on Saturday, August 7, 2021 4:08 PM

7j43k
You use the "total width of the gage" to check for NMRA horizontal clearance on straight track.

I missed that part. It must be in one of the detailed RP pages.

I wonder why they did not put a lettered measurement on the full width and reference the specific RP like they did for other dimensions.

Maybe that is what dimension "A" is, just doubled for both tracks.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by 7j43k on Saturday, August 7, 2021 4:39 PM

SeeYou190

 

 
7j43k
You use the "total width of the gage" to check for NMRA horizontal clearance on straight track.

 

I missed that part. It must be in one of the detailed RP pages.

I'm not sure it is.  But that is definitely what it is supposed to be.

I wonder why they did not put a lettered measurement on the full width and reference the specific RP like they did for other dimensions.

Maybe that is what dimension "A" is, just doubled for both tracks.

 

dimension A is the distance from track centerline to minimum clearance. 2 X A is for the full width.

 

Ed

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Posted by SeeYou190 on Saturday, August 7, 2021 4:54 PM

Thanks Ed. I think I got it now. I appreciate the help and clarifications.

However, I think I will stick to using the big Athearn High Cube for clearance checks. It is larger than any other train car I will ever run, so if it is good, all is good.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by Pruitt on Saturday, August 7, 2021 9:20 PM

7j43k
Mark,

Equipment has NOT gotten wider over the years.

In 1955, Plate B (the only one shown in my ORER) width was 10'-8".

In 2015, all Plates showed a maximum width of 10'-8".

 I expect the widening of the gage was done for good and thoughtful reasons.  But it wasn't done because the prototype got wider.

 Ed

That's all well and good Ed, but...

Did you check 1925? 1880? or are you saying that modern equipment is essentially the same width as 1880's equipment? Or 1930's equipment? (Railroading did exist before 1955, you know Wink).

Prior to the 1950's, I believe equipment was generally a bit smaller (when boxcars were commonly single-sheathed wood siding on steel frames, or when most cars used truss rods, as examples). Either that or I have a bunch of badly undersized early 20th-Century-to-WWII rolling stock. Clown

But I take your point about the more recent decades.

For the modern era, here's how a few of the different prototype railroads define over-width loads.

BNSF:

Machinery & Oversized Shipments | BNSF

Note that a load isn't considered oversized (in width) until the width is more than 11 feet. That's 4" OVER your 10'-8" quote.

UP (same as BNSF): UP: Seven Steps to Shipping Dimensional Loads

Interestingly, CSX over-width size is your stated 10'-8". Dimensional/Clearance - CSX.com

NS goes even farther. Any dimensional load over 10'-6" requires special attention.

In any case, the standards gage has changed over the years, for usability improvements, changing NMRA track standards, and prototype equipment clearance requirements.

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Posted by 7j43k on Saturday, August 7, 2021 11:48 PM

Pruitt

 

 
7j43k
Mark,

Equipment has NOT gotten wider over the years.

In 1955, Plate B (the only one shown in my ORER) width was 10'-8".

In 2015, all Plates showed a maximum width of 10'-8".

 I expect the widening of the gage was done for good and thoughtful reasons.  But it wasn't done because the prototype got wider.

 Ed

 

That's all well and good Ed, but...

 

Did you check 1925? 1880? or are you saying that modern equipment is essentially the same width as 1880's equipment? Or 1930's equipment? (Railroading did exist before 1955, you know Wink).

I do know that railroading existed before 1955, Mark.  But the NMRA gage was established in the fifties, so I thought it appropriate to start with that era.

My point was that the width standards between when the NMRA Standards Gage was established and today have not changed.  And so that is not the reason for widening the gage.  If you disagree, I look forward to your thoughts.

Prior to the 1950's, I believe equipment was generally a bit smaller (when boxcars were commonly single-sheathed wood siding on steel frames, or when most cars used truss rods, as examples). Either that or I have a bunch of badly undersized early 20th-Century-to-WWII rolling stock. Clown

As I said, my reference is for the fifties.  Earlier equipment was smaller.  If you want to visit and work in previous eras, I'll note that the NMRA has an "Old time/Narrow Gaugee Era" standard that should be appropriate.

 

I appreciate your pointing out oversize standards.

I was talking about AAR Plates.  They are the standard for interchange.  They may, of course, be ignored by railroads, if they so please.

Ed

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Posted by richhotrain on Sunday, August 8, 2021 6:12 AM

7j43k

You use the "total width of the gage" to check for NMRA horizontal clearance on straight track.

That may be, but that isn't going to help with installing curved track.

If the total width of the gauge is used to check for NMRA horizontal clearance on straight track, is that meant to measure the minimum clearance? I prefer to set straight track 2" on center, especially on the mainlines because that corresponds to the distance requirement to match up Peco #6 turnouts on crossovers and crossings. I would need to check that distance requirement on Atlas turnouts.

Rich

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Posted by ATLANTIC CENTRAL on Sunday, August 8, 2021 7:42 AM

richhotrain

 

 
7j43k

You use the "total width of the gage" to check for NMRA horizontal clearance on straight track.

 

 

That may be, but that isn't going to help with installing curved track.

 

If the total width of the gauge is used to check for NMRA horizontal clearance on straight track, is that meant to measure the minimum clearance? I prefer to set straight track 2" on center, especially on the mainlines because that corresponds to the distance requirement to match up Peco #6 turnouts on crossovers and crossings. I would need to check that distance requirement on Atlas turnouts.

Rich

 

Atlas Custom Line #4, #6, and #8 turnouts all build crossovers with 2" track centers and yard leads with 2" track centers without any cutting or spacer tracks.

The 12.5 degree crossing is the same angle as the frog of the #4 turnout (which is really a #4.5), the 25 degree crossing is therefor twice the #4 frog angle and the 19 degree crossing is exactly twice the angle of the #6 frog.

The wye frog is twice the #6 frog or 19 degrees for the construction of double track wye diverging routes using the 19 degree crossing, each route having the same diverging "curve/angle" as the #6.

Atlas once published a track plan book that had all these kinds of standard arrangements diagramed, and maybe some of their publications still do, I just don't have any of the newer track plan books from them.

Most of the double track bridges in the industry are designed for 2" track centers, and have been for many decades, or more like over a half century.

Walthers, Shinohara, Tru-Scale back in the day, Bachmann and others all use or used 2" track centers for premade crossovers and double crossovers.

The vast majority of commercial double track tunnel portals throughout the decades have been designed for 2" track centers.

And my Bachmann EM-1 passes my few 80' passenger cars on 36"/38" radius double track curves with no clearance issues. From there my concentric curves only get bigger......

Sheldon

 

    

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Posted by richhotrain on Sunday, August 8, 2021 7:51 AM

ATLANTIC CENTRAL

Atlas Custom Line #4, #6, and #8 turnouts all build crossovers with 2" track centers and yard leads with 2" track centers without any cutting or spacer tracks.

Thanks for that, Sheldon. I thought that was the case, but I couldn't muster up the energy to go down to the layout to check.

Rich

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Posted by 7j43k on Sunday, August 8, 2021 8:26 AM

richhotrain

 

 
7j43k

You use the "total width of the gage" to check for NMRA horizontal clearance on straight track.

 

 

That may be, but that isn't going to help with installing curved track.

 

If the total width of the gauge is used to check for NMRA horizontal clearance on straight track, is that meant to measure the minimum clearance? 

 

 

The gage isn't for installing track.  

It's for checking clearances for builings, bridges, scenery, etc. on straight track.

If you want one for a particular radius of curved track, you can build your own out of styrene using the information in RP-7.  Since you don't have to include all the notches and bumps of the regular gage, it's not difficult.

 

Ed

 

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Posted by Lastspikemike on Sunday, August 8, 2021 9:58 AM

So you can't fit a hobby industry standard double tunnel entrance over a curved double main line?

Alyth Yard

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Posted by SeeYou190 on Sunday, August 8, 2021 10:07 AM

7j43k
The gage isn't for installing track.  

I use Micro-Engineering three point gauges as I install track.

The NMRA "gage" is used for checking and troubleshooting.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by ATLANTIC CENTRAL on Sunday, August 8, 2021 10:25 AM

Lastspikemike

So you can't fit a hobby industry standard double tunnel entrance over a curved double main line?

 

That is not a yes or no question. Some manufacturers do/did allow extra width on double track tunnel portals, some not so much. Different companies have been making different stuff for 70-80 years now, maybe longer. Ther are no tunnel portal design police......

But even if some extra width is given for outboard clearance on curves, the total width is likely to be based on center to center distances only slightly above 2" to allow a proper appearence on straight track at 2" centers.

Again, at 36" radius and above, not really an issue, 2" works.

For me personally, 36" radius is my bare minimum mainline radius, and actually my bare minimum for anything other than urban industrial sidings, so clearances beyond 2" are not an issue for me.

I understand not everyone has that kind of space, or wants to use their space that way. That's fine.

But long before me lots of smart people in this hobby figured out that these standards made sense as a good compromise between prototype practice, good model operation, and realistic model appearence.

Track centers 2" - more on curves if radius is less than 36"

Easements - 1/2" offset, 12" to 18" total length

Curves - 36" radius allows operation of virtually all equipment and looks realistic. Allows operation of working diaphragms comfortably.

Turnouts - #6 or greater for all mainline/yard trackage, #4 for industrial trackage.

Superelevation - optional - 1/32" to 1/16" max.

 

There is a reason way modular groups use 48" radius.............

A great many of the curves on my new layout will be in the low to mid 40's.......

I'm way happy to build less layout in more space and have broad vistas and reasonably realistic curves. Still selectively compressed........

Sheldon  

    

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Posted by RR_Mel on Sunday, August 8, 2021 11:08 AM

I added two ¼” inserts to these Pike Stuff Tunnel Portals so my articulated locomotives would clear the portals.  One ¼” insert on each side of the center bolder to increase the width ½”.  Back in 1988 I didn’t have a NMRA gage, when I finally got one it worked out perfect in my tunnel portals.




The inside curve is 34” center the outside is 36¼” center code 83 Atlas Flex.  My straight mainline double track has standard 2” center to center spacing.  I don’t remember where I got the info to go with 2¼” spacing on my curves but it has worked great for 33 years.

I began with 85’ passenger cars and they didn’t have any problems.  I switched to Athearn 72’ passenger cars because the 85’ cars looked out of place on my small layout.




Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951



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Posted by PC101 on Sunday, August 8, 2021 8:37 PM

7j43k
 
SeeYou190

 

 

It looks like what I thought was correct. The total width of the gage is not used for checking anything.

Am I missing something?

 

 

 

 

 

You use the "total width of the gage" to check for NMRA horizontal clearance on straight track.

Considering that the width of the MARK V gage mirrors almost exactly the required clearances in Washington and Oregon (and likely elsewhere), it's not totally useless. It's also good for having a place to put all the notches and bumps.

That funny little notch on the left is to check platforms.

Oh.  It turns out the MARK II Standards Gage was issued in the early sixties, to reflect the new RP25 flanges.  I doubt the MARK I was marked with a "I".  I MIGHT have one somewhere.  I MIGHT have lotsa things.  Somewhere.

Pretty sure I've got a MARK II.

Ed

 

I am holding a first issue (??) and a Mark II GAGE. I'm going to be richLaugh. The NMRA STANDARDS GAGE HO SCALE prior to the ''MARK II'' has no ''MARK I'' or any ''I'' on it.

The ''first issue'' NMRA standard gage is of a softer metal then the MARK II. Both measure 1.996-5'' across there width.

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