I’ve bought a new diesel (Liliput zillertalbahn 4 wheeler + jackshaft) for testing purposes. It’s not the most powerful in the world and struggles with 4 WHR carriages up a gradient but it runs really well with lesser loads, was quite cheap (new at £50) and has a 6 pin DCC plug on board making switching from DC to DCC easy.
I’m using this little red diesel to test the mods I’ve made to couplings and bogie pivots on a test track featuring 12 inch radius curves.
The good news is that the mods have cured the problems on curves, but I am a little concerned that this has been achieved at the expense of a slightly too high ride height on the WHR carrs (FR are ok). Thus longer term I may look at alternatives to the 3mm scale plastic wheels that I have used up to now. For now they will be kept as is until there is time to switch them over (not a priority).
I’ve also added weight to the WHHR ex Vale of Rheidol van which runs far better now too.