Flange sizes

Discussion in 'HO Scale Model Trains' started by nosixoften, Feb 5, 2006.

  1. nosixoften

    nosixoften New Member

    I noticed someone mentioned a certain flange size on a thread a few days ago. How many different flange sizes are there and what difference does it make on a layout. As you probably guessed , I'm new at this. Gene
  2. lester perry

    lester perry Active Member

    Older cars & Locos may have larger flanges which will be a problem going through turnouts if you use smaller than code 100 track also flange may hit molded ties or plates.
  3. shaygetz

    shaygetz Active Member

    Generally, there are four sizes of flanges used and I won't be offended if I'm corrected :thumb: The deeper ones, affectionately refered to as "pizza cutters" in the hobby are .070" and are really only good for C100 rail. Rivarossi started knocking them down to .039" to make them more compatable with the growing popularity of C83 and C70 rails. I believe NMRA RP25s are .025", deeper than scale but much more realistic looking and generally found on most equipment today. PROTO 87 standards make it even finer, I think like .018".
  4. nachoman

    nachoman Guest

    I am only aware of one flange size that is advertized - that is RP-25. this stands for NMRA reccomendation #25. This size was designed as a compromise between appearance and reliable operation. According to the NMRA, this is about the smallest flange an HO wheel can have before having performance issues. Anything not RP-25 probably has a larger flange than this standard.

    If you plan on using code 100 rail, there will be no issues with any wheels ever made. I am told that code 83 will work with over 99% of equiptment ever made, with the exception of some european imports pre 1990. I have yet to run across anything that will not work on code 83 rail. If you are using code 70 or 55, RP-25 is a must. Most IHC and trainset quality lifelike or bachmann will not work on code 70 or smaller rail. I laid some code 70 and was disappointed when an IHC 4-4-0 would not work on it.

    so again, to answer your question, there are really two flange sizes - RP-25 and larger than RP-25. How much larger depends on the manufacturer.

  5. Glen Haasdyk

    Glen Haasdyk Active Member

    As Bob stated there are several different flange sizes but if you are running code 83(height) of rail, that only one you have to be concerned about is the old riverossi flanges which are large, but are getting rarer since they are no longer produced and you most likely will only find them on used equipment at flea markets and ebay.
    Now a question, with the proto87 flnges so small, wouldn't they be more suseptable to derailmants and car you really see the diffence when a train passes by?
  6. pgandw

    pgandw Active Member

    There are NMRA wheel standards and NMRA recommended practices. In HO, the NMRA standard permits .035 inch flanges. The RP25 (Recommended Practice 25) was developed by a few (bless their hearts) modelers who believed that better performance could be had by going to a smaller flange with a proper wheel tread taper and rounded fillet between the tread and flange.

    There are several different NMRA RP25 wheels (see RP25 at http://www.nmra.org/standards/consist.html). Normally used in HO is Code 110. The Code refers to the wheel width in thousandths of inches. NMRA track standards are based upon the Code 110 wheels. Code 64 wheels are very close to exact scale, Proto87. However, Proto87 track standards are different than NMRA to account for the much narrower wheels. Proto87 wheels will generally not run very well through NMRA turnouts, and Code 110 RP25 wheels will not go through Proto87 flangeways and/or guardrails.

    NWSL offers Code 88 wheels which do track fairly well through NMRA standard track. These have a better appearance, mostly due to the narrower tire width rather than smaller flange size. Code 88 wheels are most commonly used in HOn3 because the smaller diameter wheels magnify the visual impact of over-scale tire widths. NWSL also offers Code 64 wheels gauged either for Proto87 or NMRA track. The latter have problems with some commercial turnouts. See the NWSL site HO wheelsets brochure for details. Unless you are going to hand lay your turnouts (in which case you choose your standards), the recommendation is to stick with Code 110 or Code 88 wheels (the latter for better appearance, again mainly in tire width). With Code 88 wheels you may be making "adjustments" to some commercial turnouts for derailment-free performance - but you do that already, don't you?

    Due to the inherent "slop" between the HO gauge for wheels and track, the prevailing wisdom is to keep the track gauge right at HO minimum throughout the turnout, and adjust the frog and gaurdrails to correct flangeways and check gauge accordingly. Many plastic frogs are not sharp enough for reliable tracking, which forces dependence of the guardrails and a filled in frog flangeway for proper wheel guidance. When this happens, deep flanges are a problem.

    Proto87 requires tight track standards. The magnitude of acceptable vertical irregularities that are acceptable is much smaller. Trucks, in general, must be equalized. However, when this is done, the tracking is every bit as flawless as you might expect. See the video on the Proto87 web site for the demo.

    The RP25 Code 110 wheels really didn't become universal until the late '60s. US HO manufacturers generally used .035 flanges, and others have discussed European manufacturers - Rivarossi was the predominant import, used by AHM. The interim Rivarossi .039 flanges and the older US .035 flanges will run on Code 83 track, but will often hit the spike heads on Code 70 and smaller track. RP25 wheels do fine until you reach Code 40 track, where the sufficiency of flange clearance depends on the height of the spike heads. That is why many modelers glue or solder Code 40 rail, rather than spiking it.

    Hope this is of interest to some.

    yours in tracking
  7. nachoman

    nachoman Guest

    excellent post, fred!
  8. nosixoften

    nosixoften New Member


    Hey, thanks to all who replyed to my question. Sincemost of the equipment that I have comes from a collection of late 70's and early 80's I will probably go with code 100 track to be on the safe side. Thanks again . Gene
  9. green_elite_cab

    green_elite_cab Keep It Moving!

    Does anyone sell geared wheel sets with better wheels if i ever wanted to replace them? I don't plan on replaceing anything soon, but just incase the need arises, its good to know.
  10. shaygetz

    shaygetz Active Member

    www.nwsl.com sells some geared sets. They sell drop in replacement wheels for Athearn deidels that are top notch. For the most part though, you'll have to turn them down yourself or find someone to do it for you. Don't do as some have in the past and try to turn them on the loco by applying power to it then running the wheels under a file. While it can and has been successful for some in the past, the risks for motor burnout and filings in the drive train are just too great.
  11. lester perry

    lester perry Active Member

    While we are speaking of wheel sets how do I get rplacement ones for P2K GP7,9 & 30. It appears that I have some split gears and Walthers (the new tyco owners) doesn't care.
  12. shaygetz

    shaygetz Active Member

    Most folks I know, myself included, are simply buying up units at swap meets for parting out, especially for P2Ks and Athearns. Sounds harsh but it's economical and---conforms to prototype practice for the same reason. :thumb: :thumb:
  13. zedob

    zedob Member

    Speaking of wheels, flanges and gauge. Don't forget to check the wheel sets for all new locos and rollingstock against an NMRA gauge.:thumb:

    The last two locos I bought (a MDC oldtimer 2-8-0 RTR and a Bachmann 2-8-0, both HO) were so out of gauge that I was shocked. I can see one or two sets of wheels on the tender, but on every axle, including the drivers, wow. Someone in the QC depts of both of those companies needs to get re-trained (pun intended:D ), or someone needs to recalibrate the wheel setting machine. There is no reason why either one of them couldn't have been closer to gauge, if they follow NMRA standards. They definitely could have been closer.

    I wonder if Baldwin or Lima let their locos go out the door with the wheels 2" out of gauge?
  14. Russ Bellinis

    Russ Bellinis Active Member

    You might contact Northwest Shortline. They have sold replacement wheel sets for Athearn for years, so they may have some that will work in P2K locos.

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