Hi Graham, in reading all the knowlegable answers, I thought I'd let you have my thoughts, from a purely mechanic's perspective, from here in the colonies. John has the straight forward repair, and it's nice and solid, I'd add welding up the axle where its buggered up, and turn down the welded section, over replacing the axle, all that assuming the rest of the axle is in good shape and solid. What John says gives you four separate locks, and substantially more bearing area of the locks, which would make it far more resistant to working loose, and once it works loose to start with, there's only looser, no turning back. I believe I'd braze up the threaded section in the wheel, assuming its cast, and then bore to get back to round, and put the screws in three virgin places, and clean up the key to at least a tight push fit, when it goes in the wheel and axle together, even if it means a larger key. That wheel is essentially acting as a flywheel, and driving the axle, so the wheel is going to act and react to the engine directly, leaving all the mass and inertia of the axle to follow, so the key, pun intended, to keeping the two solid, is to work from the wheel to the axle, as far as stresses go, rather than the conventional axle to wheel, which assumes the axle drives the wheel. I'd also locktite the wheel and axle joint when everything is fitted up for the final assembly, if it can't start working loose, it won't get looser with time. The idea of adding live bearings is a good one, if you're ready to go all the way with a whole new axle, and then it can be a bit oversized, and allow a better clean up of the hub, and a good chance of finding the opposite wheel starting to work loose, and get it solid and well keyed before any damage is done. This looks a lot like farm equipment repair, if you don't mind my saying so, similar problems, lots of torque, lots of load, and stop and go making inertia a serious factor. I'd sure like to lay my own hands on that bit of work, not much rail work unless one is close and part of a club over here. Something about steam engines, tied to flanged flywheels, running on tracks, with boilers attached to the engines, in tandem, and frames bolted on to the engines and boilers, and pulling boxes for stuff or people, from the bolted on frames, but brought down to the essence, two tandem steam engines with driving and rolling wheels attached, and a boiler to provide the steam - the most basic engine/drive system starting the steam driving idea from the beginning of the steam age. It feels subtly primitive and original, and connects with the guys who had to figure all this out from scratch, just using their noggins, and learning from what breaks.
I've always felt steam engine enthusiasts and motorcyle drivers are of the same breed, just wanting to put wheels on an engine, and drive the engine around, with the necessary equipment attached, and no more. Some jobs get you paid, other jobs you'd pay just for the privilege of doing it, at least I find that happens, all though even the second kind, the owner wants to pay.
cheers, I hope you enjoy the repair as much as we enjoy watching it unfold.
mad jack
