I once thought that freight and passenger cars use the same wheel size until I found out that early freight cars used the smaller 33’ wheel size. Then again I just discovered that modern freight cars use the universal 36’ wheels along with their modern freight trucks. Then it means that a modern 60 ft freight car cannot couple onto the old 40 ft freight car because the coupler height won’t be the same. However did railroad company upgrade the trucks and/or wheels of older freight cars or any conversion?
Then it means that a modern 60 ft freight car cannot couple onto the old 40 ft freight car because the coupler height won’t be the same.
Incorrect coupler height is universal between passenger and freight equipment it would be completely impractical for the prototype to have different coupler heights. On your model railroad rolling stock the coupler height is adjusted by shimming the truck. This is typically done by inserting a small fiber washer between the mating surface of the truck and the underframe of the car. (where the screw goes) You can check the coupler height with an NMRA gage but an easier and more practical way to go is by using a coupler height gage from Kadee they also see the fiber shim washers i was referring to. Another method but less popular way of adjusting coupler height is by placing a shim between the draft gear box and the car body again an item sold by Kadee and other manufactures. In some cases you may have to resort to using couplers with an underset or overset.
If you check out Kadee’s website they are pretty informative when it comes to all things couplers.
100+ ton capy cars have 36’ wheels. 70 ton cars have 33" wheels.
Absolutely not. The couplers are at the same height. If the cars are going to use 36 wheels they build the car so the coupler height will be correct.
On real cars, the coupler height is standard for all common carrier cars. This includes those with 33" and 36" wheels as well as the 28" ones used on some intermodal equipment. Don’t forget, too, that most diesel locomotives have wheels considerably larger than those on the freight cars, yet all of the couplers still line-up correctly.
For our models, most manufacturers follow recommended standards regarding coupler height, although there may be many deviations. If you change the wheel size on a car which already has its couplers at the correct height, the height of the couplers will change, too.
Wayne
Back when I started, 33" wheels were sold as “freight” wheels and 36" wheels as “passenger” wheels but in point of fact, as the above posters indicate, heavy freight cars now typically have the 36" wheels and yes there were some passenger cars that had 33" wheels as well.
Not to belabor the point but go to almost any railroad museum and you’ll see the newest equipment mates up just fine with the oldest equipment (assuming they maintain their coupler heights correctly) regardless of wheel size – including, say, an 0-4-0T with 56" drivers.
Not exactly on topic but at the NMRA Convention in Milwaukee last week, FRA Inspector Dave Sima showed a slide of an 85 or 89’ flatcar that had an excessive load right in the middle of the car- causing the middle to sag and the couplers to raise up at the ends until there was only 2" on contact between couplers. The weight was not excessive but the placement of the load was incorrect. I had never focused on this before, but the loading rules even call for ballast to be added to flat cars to even out the loads correctly.
Dave Nelson
The standard height for couplers is 34-1/2" (2 ft., 10-1/2 in.) above the railhead, measured to the centerline of the coupler head or shank. It’s the same for locomotives, freight cars, and passenger cars, and may not vary with the diameter of the wheels.
So long,
Andy