I don't have the NMRA recommended practices documents in front of me, but my recollection is that RP-25 is not scale dependent at all. in other words, a code 110 wheel with contour conforming to RP-25 would have the same profile whether used in S or HO. Would be glad to be corrected by evidence.
The word contour is used to describe the various parameters that define the shapes of the tread and flange, and the curve (fillet) that connects them, along with the angle of the tread and the relative dimensions of the component parts of the profile of the wheel. Oh, and by the way, all model railroaders owe a huge debt of gratitude to those pioneers who devised the NMRA track and wheel standards and recommended practices--we are reminded of it every time a piece of rolling stock successfully traverses a section of track! Fred T -----Original Message----- From: Darrell <[email protected]> To: [email protected] Sent: Sat, Jan 22, 2011 1:36 pm Subject: {S-Scale List} Re: Comparing wheel treads. RP25 contour is not scale specific. But the flange dimensions, and to some degree the wheel width, are. Therefore an HO RP25 wheel is going to have a smaller flange contour than an S RP25 wheel. You have to pull up the different standards tables for the wheels you're comparing and check the different standards to see if they will be compatible. The NASG and the NMRA standards are all available online if you go to their sites. HO RP25 wheels are going to differ from BOTH S scale standards, but will be much closer to the Proto64 standards. Darrell --- In [email protected], "Tom Hawley" <t.hawley@...> wrote: > > ----- Original Message ----- > From: Darrell > . . . . . . . . HO RP25 wheels have a smaller contour than S RP25 wheels. . > . . . . . . . . . . Hope this hasn't confused you.... . . . > > > > > > > > > > > > > > It's probably confused a lot of us, though it probably won't make much > difference in our day-to-day modelling. What exactly do you mean by > "contour"? And which, according to your theory conforms with, and which > deviates from the "code 110" dimensions in the NMRA's RP 25? The various > codes in RP25 are not scale-specific, except that you have to find a code > that works with the S3 and S4 dimensions you're using. > > Tom Hawley -- Lansing Mich > [Non-text portions of this message have been removed] ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/S-Scale/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/S-Scale/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
