Prototype Gauge Adjustment

Discuss the prototype and how to model it.
Proton
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Prototype Gauge Adjustment

Postby Proton » Thu Jul 21, 2022 12:23 pm

Hello Everyone,

The topic of gauge adjustment on the prototype came up at a dinner party last night. Initially it was in respect of concrete sleepers, but then included wooden and steel sleepers.

So, how is track gauge adjusted for the different sleeper types?

Any links etc welcome/

John

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Julian Roberts
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Re: Prototype Gauge Adjustment

Postby Julian Roberts » Thu Jul 21, 2022 2:50 pm

There is a terrific amount of info on modern track here. It mentions a network decision to reduce the gauge from 1435 to 1432mm that after a few years was found unsatisfactory and abandoned. Don't recall that it related to a certain type of sleeper though.

https://www.mmrs.co.uk/technical-articl ... anent-way/

Proton
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Re: Prototype Gauge Adjustment

Postby Proton » Thu Jul 21, 2022 3:12 pm

Thanks for this Julian. Having done a quick review and a word search, it certainly looks as though, for concrete sleepers, the gauge cannot be adjusted at all, and the sleeper would have to be set for a specific case requiring gauge widening.

I wonder if the same is true for wooden sleepers? We all know how turnout timbers are pre-drilled etc, like a kit really, so when gauge widening is required on plain track would there be a set of timbers numbered and assigned for the transition curve?

John

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grovenor-2685
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Re: Prototype Gauge Adjustment

Postby grovenor-2685 » Thu Jul 21, 2022 3:21 pm

With traditional Pandrol clips the plastic insulators between the clips and the rail come in a variety of sizes (and colours) that allow small adjustments of gauge, used to cover the 1432 - 1435 isssue as well as gauge widening. I assume that this also applies to the newer fastclip designs. For the 1432/1435 issue see the attached.
track-gauge.pdf
(3.43 MiB) Downloaded 40 times
Regards
Keith
Grovenor Sidings

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Julian Roberts
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Re: Prototype Gauge Adjustment

Postby Julian Roberts » Fri Jul 22, 2022 9:10 am

This may be of interest too?

Not sure if you were also talking about gauge widening on curves John but its here, nowadays 5 increments according to radius.
Attachments
Track.pdf
(363.45 KiB) Downloaded 44 times

Proton
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Re: Prototype Gauge Adjustment

Postby Proton » Fri Jul 22, 2022 4:59 pm

Hi Julian,

Yes, that's exactly what I was looking for!

Thank you!

John

andrewnummelin
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Re: Prototype Gauge Adjustment

Postby andrewnummelin » Sat Jul 23, 2022 3:42 pm

Julian Roberts wrote:This may be of interest too?
...

I thought this document contained some very interesting numbers in addition to those related to gauge widening - we tend to quote our gauge as 18.83mm without any tolerances so below are the numbers in mm related to gauge converted to 4mm:1' scale.

<18.71 report for correction
<18.75 report for correction if over 131mm (10m prototype) for scale speed >100mph
18.77 minimum for vertical rail in moveable parts of S&C
18.79 nominal 4'8⅜" for some prototypes
18.81 minimum for inclined rail in moveable parts of S&C
18.83 4'8½"
18.87 maximum for vertical rail in moveable parts of S&C
18.91 maximum for inclined rail in moveable parts of S&C
>19.09 take steps to control if visible defects (static gauge)
>19.23 take steps to control (static gauge)
>19.44 stop traffic (dynamic gauge)

And whatever the gauge, it should not vary by more than 0.1mm over 40cm. (A visual requirement for a model rather than a performance one I believe.)

It was noted that there did not seem to be a minimum gauge below which traffic should be stopped - does this never happen on the prototype?
Also noted is the clear message that extra care is needed with switches, but I guess many of us know that from personal experience!
Regards,

Andrew Nummelin

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Julian Roberts
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Re: Prototype Gauge Adjustment

Postby Julian Roberts » Sat Jul 23, 2022 7:20 pm

Check rail tolerance scales down to - 0.04 or + 0.01 :o
Amazing! Lucky P4 more tolerant than allowed on the prototype. No figure for back to back in the document.

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grovenor-2685
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Re: Prototype Gauge Adjustment

Postby grovenor-2685 » Sat Jul 23, 2022 9:04 pm

Track does not have a 'back to back'. You need to find a wheelset document for that. :)
Regards
Keith
Grovenor Sidings


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