I spent a lot of time testing the new track layout making sure the track layout problem was completely resolved. For the testing I went thorough most of my Loco stock – but found the Bachmann Kinlet Hall, Class 44 ‘Penyghent’, Super Voyager and the Hornby Prairie and Fowler tank engines the most useful as they were the most ‘sensitive’ to bad track.
After this I started to go through my range of coaching stock and discovered the rich world of wheel ‘back to back’ measurements. I discovered that certain coaches – even some very new ones would have a tendency to derail at points when the track geometry was correct.
After doing some research on the web I measured the wheel ‘back to back’ – (The distance measured between the inside edges of the two wheels on an axle) and found that this varied between 13.8mm to 14.7mm. I know this does not sound like much but makes all the difference when the wheel has to traverse a point with all the check rails etc. This is less of a problem with the older ‘less scale’ wheels – but is much more of an issue with the finer (thinner) wheels on modern stock. On my layout, using basic Hornby points I found the optimum back to back measurement was 14.3mm. Measuring lots of wheels using a digital calliper became a bit of a pain, so I asked a friend who is a whizz with fine metal work to produce a ‘gauge’ for me. This gauge is a small piece of metal 14.3mm across that allowed me to quickly check the wheel back to back measurement. If the ‘gauge’ fits tightly between the wheels being tested I know the gap is right. Otherwise it’s a case of removing the wheel and carefully adjusting it to the right size.
I am also using this opportunity to replace the plastic wheels of some of my older carriages with new metal wheels. It makes them run much better and helps keep the track clean.