Okay - Track laid, well most of it, wiring in, running test trains. The layout has ended up with effectively two ovals, an upper and lower with a ramp down between them, the upper also has some gradients on it (very shallow though). Minimum radius is Peco 2nd radius (which stll seems a bit tight to my eyes). He missus has bought him a rake of 3 coaches, 2/hand but seem to run smoothly enough, centre coach has full couplers, outers have only the loop. Couplings are the standard Tri-ang tension lock type, sams as I had on my childhood set with its minumum radius curves, never had a problem with them then.
So - Passenger train left running on upper level whilst fiddled about with lower level tracks - Very occasionally one or other of the couplings comes undone, leaving a coach behind.
Meanwhile on the lower level started running test trains and found the old Tri-ang cattle wagons tended to 'lock' the couplings on some curves, leading to derailments. Put on one side for investigation. However the new Hornby 5 plank minerals occasionally 'uncouple' for no apparent reason.
Any hints tips or suggestions for tension lock couplings?
Regards
Mike