Atlas 2-rail trucks and wheels

The first rule for me was 70-ton 33" vs 100-ton 36", sounds easy, but....  Prototype pics make it easier to decide, covered hoppers and tank cars are simple to spot.  Car size isn't always a sure thing - 2 bay open hoppers are small, but load weight and car height?  Coal's not as heavy as rock, so modern (whatever that means) 2-bay stone hoppers will have 36" wheels.  Wheel diameter was an option on other car types depending on anticipated load weight.

Questions I can't answer: could friction bearing trucks have 36" wheels?  How many 38" wheelers (125-ton) are around, what car type(s) ... hoppers?  Do wheels vary to any rules on articulated sets: end/shared trucks.

If this is something you haven't concentrated on before, you'll be surprised how quickly you'll start being able to spot 33" or 36".  How much of the wheel can you see above the the truck frame for one?  Yes, you can spot that 1-1/2" difference!

As a modern (70s/80s) modeller I don't fret about 40- or 50-ton truck differences and, of course, Atlas slimmed their truck design to show they genuinely do care about 2-railers(?!?). 

Jason

I don't know about the 70 ton covered hoppers or the 11,000 gal tanker.   Maybe someone will come back with some info.   On the others, I am pretty sure 33 inch wheels would be accurate.

Atlas in my opinion made a boo-boo on the 50ft express reefer.    I think that should have 36 inch wheels and they delivered it with 33 inch.    To me, it looks a lot better with the bigger wheels.

When atlas slimmed down the trucks, they also had to shorten the axles.     So early production wheelsets will have axles too long for newer trucks.   And late production axles will be sloppy in the earlier wider trucks.   I would guess the trucks you tried to put them in were newer and the axles were the original Atlas length.    Both lengths of axles still seem to be floating around but I have bought mostly used lately, so all new stuff might be narrower.  

While heavier newer cars generally have 36 inch wheels, I have heard that some autoracks have 28 inch wheels because of the height.    Also they be fairly light, but not sure.

@lionel1946 posted:

Can someone fill in the blanks?

40-foot wood reefers
40-ton Bettendorf trucks with 33-inch wheels

36-foot wood reefers
40-ton Bettendorf trucks with 33-inch wheels

70-ton covered hoppers
??-ton ?? trucks with ??-inch wheels

50T Bettendorf / 70T Roller Bearing (33" wheels for both)

8000 gallon tank cars
??-ton trucks with ??-inch wheels

50T Bettendorf (33" wheels)

11000 gallon tank cars
50-ton friction bearing trucks with ??-inch wheels

33" wheels. I did see at least one 11,000 gallon tank car with 70T Roller Bearing trucks.

Not sure when/why I picked up the 36-inch conversion kit; must have been such a good price that I didn't notice the size.

Thanks

Atlas only makes 3 types of trucks: 50T Bettendorf (33" wheels), 70T Roller Bearing (33" wheels) & 100T Roller Bearing (36" wheels). Well, 4 if you count the 125T Roller Bearing trucks (38" wheels) for the Gunderson Maxi IV's.

The reefers that come with 40T Bettendorf trucks are advertised as having "Bettendorf-style" trucks.

Thanks for the info guys. Here is another example from the world of Weaver. I have a Mobilgas tank car, marketed as a 40-foot tanker, but graphics indicate 16,835 gallons. My only pieces of Weaver rolling stock are these Mobilgas tankers. Anyway, the two examples I have both come with what appears to be 70-ton roller bearing trucks, one in plastic and one in metal. I had a chance to pick up a set of Weaver metal 2-rail trucks, but sadly they are Bettendorf-style trucks. I may put them on anyway, just to improve rolling characteristics.

See below for comparison between the plastic roller-bearing and the metal Bettendorf.

Here's a picture of 3 Weaver trucks: plastic 70-ton roller bearing (36-inch wheels, I think); metal 70-ton roller bearing (36-inch wheels, I think); metal Bettendorf style (33-inch wheels, I think).

Too bad we couldn't talk Kadee into doing O Scale trucks.  They seem to be doing superb work in other scales.

I have both Weaver diecast and plastic trucks/wheels and find the latter to roll just as well as the former.

I converted MTH 3-rail RB trucks to 2-rail using Intermountain 33" wheels and they are super smooth. The same goes for some Lionel friction bearing trucks that now have NWSL 33" wheels.

I don't care much for spinning bearing caps like Atlas has been using for the last 15+ years as I find the cap gets caught on the yoke as the wheels are rolling. Not all of my Atlas RB trucks do this but there are a few and it creates drag.

I definitely prefer pointed axles over shouldered.

Yes, I've been down that road too. Fortunately, North West Short Line can cut the wheels for you if you provide the axle types and measurements. I have some cars that I'm converting and I'm going that route since the cost is about the same as replacement trucks without having to hunt down the proper matches. Unlike the Atlas axles, NWSL replacement axles are only insulated on one side, so be careful when reassembling the truck.