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Proto:64 - NMRA Standards

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NMRA P:64 Standards

Last Updated June 02, 2007

 

Comments

A word about the current P:64 standards. The original proposal, listed <here>, has unfortunantly proved less than workable.

Enter The NMRA Proto Effort. This effort started with 1/4"AAR and worked till that became P:48. The current Standards, listed below, use an engineering allowance called FIT with any scale less than 1:56. As demonstrated by our original proposal we do not believe this necessary above 00 scale (1:72). Therefore; We asked that the spread sheet be modified to reflect this and the result is the refinement, listed <here>, which needs to be tested before final adoption.

    


 Proto:Scale Ratio Gage Fit Slide









Results: Proto:64 64.00 Standard 0.001 0.002

TR-1-2005
6/2/2007



Select:
56.5 Variance
See TN-1.1.2 for formula explanations


















S-3.1 TRACK G C S F F H P R *
Name of Scale Track Gage Check Gage Span Flangeway Frog Flangeway Guard Flange Depth Switchpoint Spread Railhead Radius
Min Max Min Max Min Max Min Max Nominal Min Max Min Max


Proto:64 Inch 0.883 0.902 0.851 0.853 0.814 0.823 0.028 0.030 0.031 0.020 0.809 0.006 0.009
mm 22.43 22.91 21.62 21.67 20.68 20.90 0.71 0.76 0.79 0.51 20.55 0.15 0.23



S-4.1 WHEELS K B N T D


Name of Scale Wheel Check Gage Back to Back Wheel Width Flange Width Flange Depth WHEEL GAGE

Min Max Min Max Min Max Min Max Min Max Min Max




Proto:64 Inch 0.844 0.849 0.825 0.834 0.087 0.092 0.017 0.019 0.018 0.020 0.859 0.872

mm 21.44 21.56 20.96 21.18 2.21 2.34 0.43 0.48 0.46 0.51 21.82 22.15

                               

 

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