When changing Trucks: let's say from 3Rail to 2Rail. OKay. Do you have an actual tolerance you consider for how far the distance should be from the truck bolster to the floor for smooth operation?
Now: if you are trying to re-use the trucks but want to change the wheelsets: What do you use as a guide to tell you if the axle tolerances are sufficient?
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Hi Jim
There's no 'tolerance' persay, just that sufficient space is required for the truck to swing freely. More important is that the couplers of your cars are all at the same height. Because manufacturers have their own designs which always seem to be different, you may need to add washers to some cars, and trim some material off others to get them right - if trimming material off is too hard, add shims to the couplers to make them lower. This is where a coupler gauge is very handy....being the complete tightwad that I am, I make my own from blocks of wood cut to match Kadee's standards.
I'm a complete greenhorn when it comes to replacing axles (I prefer to swap the whole truck, too hard to buy spare wheelsets where I live) but the key dimension here is overall length of the axle, followed by whether it has pointed or shouldered ends. NorthWest ShortLine specify this for their replacement wheelsets, and I seem to recall they also say what brands some sizes are for.
Regards
Paul
Whangarei, NZ
If you are asking about how much the truck should rock back and forth, I suggest that it is a function of your trackwork. I have excessive super elevation, so one truck needs quite a bit of freedom. On my tender drive locomotives I constrain one truck to absolutely parallel the tender underframe, to avoid torque wrapup.
The best thing to do is start simply - get a loop and a couple of cars and a locomotive, and give it a try.
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