NMRA standard and 2-rail trucks

 

Ahhh, Martin.   I read your post before a half dozen cups of coffee (well, before the 2nd cup anyway) and misunderstood what you are asking.  My apologies.

Jim Lincoln has just a replacement bolster for the Atlas roller bearing trucks for sale on the shapeways we site:

http://shpws.me/AWQC

"Any other options out there for NMRA-spec 2-rail RB trucks?"

 

   There's tons of older O trucks on the used market. They are mostly solid bearing prototypes because roller bearings were not the common truck when they were produced.The history of O scale trucks contains lots of bolster heights so we used lots of washers over the years to adjust the ride heights, and sometimes used a file if it was already too high  :>    As for an NMRA bolster height I'm not sure there is such a thing? I'm guessing that Weaver just made theirs to be similar to the popular Athearn trucks that had been used for years and Atlas made their to be similar to the popular 3 rail trucks that were on the market. Standards are great but hard to establish because everyone already has money invested in their own design....DaveB

17/32" from the top of the rail is the NMRA standard.  Unless I am reading this wrong:

 

NMRA standard - click here

That would appear correct for the NMRA Recommended Practice.

"17/32" from the top of the rail is the NMRA standard. "

 

  I wonder if that standard existed when Athearn designed their cars and trucks back around WW2 ?  and does Weaver or anyone else actually use it? I've always just taken each O scale car as a separate animal and shimmed it up or filed it down to get a reasonable approximation of the floor height needed to match Kadee couplers correct height..DaveB

Maybe Irv and his products helped define the original NMRA standards in the first place?

"Maybe Irv and his products helped define the original NMRA standards in the first place?"

 

   That's what I was wondering. Did they just pick the most widely used truck and use it :> or is the number based on some prototype height? ....DaveB

As far as I can work out, Atlas put the bolster on the truck rather than on the car; probably means the same floor can be used for 2- or 3-rail trucks. It makes their trucks incompatible with Weaver etc; this is more than just a shame, it's a pain in the posterior (or '@ss' as you'd say Stateside!!!)

 "probably means the same floor can be used for 2- or 3-rail trucks"

 

  actually the same trucks for both ,they just change the wheels. .DaveB