flying scotsman123 wrote:
It has a lot of lateral movement, and also in theory vertical, although in fact it only has about 0.5mm of that as otherwise it fouls on the body. At the moment it keeps falling off when I push it along the rails, and I'm not sure where to start. Any ideas please? I'm guessing some sort of spring arrangement is needed, but I've no idea about what, or what to buy.
I would suggest the lateral movement could be cured by simply adding washers as required.
As to the vertical movement, have you checked the accuracy/alignment of the chassis by standing it on a piece of sheet glass?
Any wobble will indicate which wheel(s) is/are out of kilter and appropriate corrective action can be considered.
If there is no wobble and all wheels touch the glass then it points to uneven track.
Just a final thought - if there is no wobble and you push it along the track without the coupling rods does it still derail? If it doesn't derail without the coupling rods, but does derail with them then it points to further adjustments being needed to the coupling rods.
Best of luck.