kirkbypete

With the N7 there shouldn't be an issue with things interfering as it doesn't have a front bogie like the A4. There shouldn't be any issues with running an A4, there have occasionally been some locos in the past that have been prone to derailing, but I don't think the A4 has ever been a particular issue. 

The track not being pinned shouldn't be too much of an issue as long as it's level, however you may find you need a track pin if pressure is forcing a bit of track to lift slightly. If you're not sure what you can do is to use the edge of a ruler on top of the tracks to see how level things are. If it's the track causing it you can usually see by running the loco slowly over a section of track where it frequently derails and if you watch the front wheels you will see it begin to rise up out track. Even if it only it derails at high speed by running it slowly you'll be able to see it beginning to happen. What you'll find is on curves in particular you need to watch the levels, and around joints at points as there a bit stiffer than other bits of track so you're a bit more likely to end up with humps at the joints.       

Thank you for the reply  , that sounds very helpful I will try the ruler , I can see that my track might not be exactly level and it does ride up a little at  the derailing point , sorry to tax your knowledge but my Oxford rail loco seems not to like the Hornby truck coupling going round corners , it looks to force it against the coupling and push it off , perhaps there is a better coupling method , could I have only one of the hooks attached for better running , I know this is a big subject !

Thanks and Regards.  Peter