Bigmet wrote:... the Bachmann Deltic which has wheels that foul the bodywork on set track R3 (and quite possibly R4, not tested), it's a long machine and the wheeltops are inside the bodywork if a scale wheel diameter is used as Bachmann have done ...
Specifically both my Bachmann Deltics run smooth and easy on the R2 on my layout, it is very strange the wheels foul on your R3 curves.
Bachmann Deltic first. You can help here, I am pretty sure when Bachmann introduced this model the body was mounted high enough above the bogies that the wheels didn't foul on the bodywork, but I cannot prove that now as mine have been altered to correct the spacing of the body above the bogies to scale
. (I can do this because the smallest curve they have to run round on my layout is 30" radius.)
So, first question what date (roughly) did you buy your Deltics?
Reason for asking, I have seen two bought about 2016, that foul on the R3 of a friend's layout, and I think Bachmann have reduced the spacing between body and bogie top, at some time after they first introduced the model.
Bigmet wrote:...I have several Co-Co and even a Co-Bo (yes I like ugly) and they run just as well and smooth as my Bo-Bo diesels and I have a few R2 curves also (and points), what fettling (of Co-Co's) do you have to do?...
This relates to track holding on curves, my experience is only with the Bachmann 37, 47, 66, and the Hornby class 30/31.
On some of the Bachmann Co-Co examples the centre wheelset was positioned slightly lower than the bogie end wheelsets. By removing the centre wheelset, and slightly opening the aperture the brass bearings are seated in, all three wheelset axle centres can be got positioned in the same plane, as they should be, and then they stay on the rails.
Hornby's class 30/31 mechanism has a very different problem in the bogies: the axle ends run in holes in brass strips which provide the pick up contact. These can deform slowly over time and the ends splay apart, until an axle end falls out of its hole. The loco derails on or after the first curve encountered after an axle end falls out. Straightening the brass strips and putting some small washers inside the gear train to keep the gears better centred inside the frame has worked well for me ever since I found this problem. (All these mechs were bought cheap s/h with mazak rot to power old Airfix GMR Brush 2 bodies, (none of the mechs yet so rotted as to fall apart...)