What would be the weight range of a pair of Bettendorf coil spring trucks with fricton bearings and steel wheels that could support a 50 ton freight car?

Figure 6,000 pounds per truck complete and you should be fine.

ETA

I'm going to have to guess in the range of about 3 ton per truck. When i moved my caboose several years ago i moved the trucks wich are Bettendorf leaf spring trucks one at a time on a car hauler trailer rated at 6000 lbs. It did the job but made the trailer squat a bit.

One thing i often wondered is both trucks have WT 5559 marked in the casting on the side frames. Would that mean each truck would weigh 5559 lbs.?

I would go a little higher-- 7500# per truck is a good number, based on my experience with these things. A 70-ton truck goes about 8500#.

Howard P.