I am little confused with these wheelset combos. Are certain sizes specific to certain cars or eras??
Rich
Hi!
I went thru this situation a couple of years ago when I replaced the wheel sets on my postwar HO stuff with Intermountain metal wheels.
Generally speaking - for rolling stock in the '40s thru early '60s, 33 inch wheels are for freight cars and 36 inch are for passenger cars. In more modern eras, smaller wheels are more prevalent, especially on trailer and container cars and the like.
Yes, the wheel size is determined by the car’s size and weight capacity. Older rolling stock had 33 inch wheels – newer high capacity covered hoppers, as an example, have 36 inch wheels.
If you have both sizes on hand it’s usually pretty easy to tell the difference by holding the old plastic wheels side by side with metal wheels.
The tricky ones are some of the double stack container well cars - the intermediate trucks often have 28" wheels to keep the car low for clearance purposes.
–Randy
Plus you have to be careful since not all models use the exact same wheel size as the prototype. For example, IIRC the old AHM/Rivarossi passenger cars used 33" “freight” wheels rather than the 36" wheels normally associated with passenger cars. You can replace the wheels with 36" ones, but you may need to shave the brake shoes (cast on to the trucks) down a little to allow for the larger wheels. I might be wrong, but I think the Trix/Marklin HO New York Central caboose that came out a few years ago used 28" wheels instead of the correct 33"??
Generally 70 ton or less capacity have 33" diameter wheels, cars over 70 ton capacity have 36" wheels.
Auto racks and some other high cars have 28" wheels in order to lower the overall height of the car.
You do indeed have to be careful and in fact the situation with the AHM/Rivarossi cars was even “worse” than what you describe. Their wheels were actually closer to 31" even for passenger cars (I guess on the theory that the huge flanges resulted in a fairly accurate overall “look”) so replacing those wheels with 36" wheels involved shaving the cast brake shoes – also the entire height of the car started to look odd and the bolsters needed attention as well. If you were thinking of body mounting the couplers you’d want to wait until after the wheel size situation was addressed, for example.
When AHM or IHC came out with replacement wheels with RP25 contour and flanges, they were still nonetheless 31" or 32" wheels. They rolled rather nicely actually.
Somewhat off topic but a few weeks ago the East Troy (WI) Electric Railroad Museum took delivery of some derelict South Shore cars, moved in a special train on the CN.
http://cs.trains.com/TRCCS/forums/t/180328.aspx
When the cars were delivered at Mukwanago WI, it was noticed for the first time that at some point a wheel had been replaced in one truck – the same truck had one 33" wheel and one 36" wheel! Whether it was that way in active service or that was strictly a temporary solution to a problem I do not know, but you can file that under your “there is a prototype for everything” caption.
Dave Nelson
Am I mistaken or did I read somewhere that cabooses also had 36" wheels. Or do they just work better with Kadee #5s in my Athearn BBs? Also, the IHC passenger car metal replacement wheels I bought a few years ago, I thought were 28", again to avoid contact with the brake shoes.
Hi Rich…
Freight cars with a 100Ton tare rating or greater will have 36" wheels. the smaller 33" wheels can be found on intermodal equipment and in the case of the spine cars, some are equipped with 28" wheel diameters, like the Front Runner Intermodal Car.
With that exception, most all modern equipment will have 36" wheel sets.
Older vintage cars had 33" wheels except for early 100 ton coal hoppers which came with the 36" wheel dia.
Hope this helps.
HeritageFleet1
Thanks for the info guys!! I just got educated! The reason for the post is that my father has some older(HO) post war freight cars, I am assuming some old athearn stuff, and he is using code 83 track and the huge wheel flanges on some of these cars actually contact the ties and the cars are very eratic and noisy as the roll along. I wanted to get him the replacement wheelsets but got a little confused when I seen the two sizes. Thanks for the help.
Rich
Rick,
Cars with a capacity up to 77 tons can use 33" wheels(actually the key is the size of the axle bearing). 100 ton capacity cars use 36" wheels, and 125 ton capacity cars usually have 38" wheels. Again, the actual axle diameter/bearing is larger. 28" wheels are used in several classes of TTX flats & auto racks to provide low clearance for these cars. Virtually all passenger cars use 36" wheels.
Jim
Another thing to note is that you should replace wheelsets with the same size. Otherwise you may have couple height issues.
Yes before about 1980-something huge flanges were the norm. Once Code 83 track came to be more accepted - probably with Walther’s introduction of their Code 83 line - flanges started getting smaller. Most everything made since 1990 or so should be fine with Code 83 or 70 track.
You might look into replacing the trucks and wheelsets, rather than just the wheelsets. I’ve re-trucked a number of cars with Life-Like trucks because they are extremely free-rolling.