Do not make assumptions when it comes to trackwork and derailments

[GWR-fan]

Until I am able to set up my permanent layout I must rely on a test track using Hornby trainset track and a L/H point to test any new locomotives to the fleet.  I have all the Peco points and flex track to build my permanent layout but find it convenient at the moment to simply clip a few pieces of track together to test any new purchases.  Up until this morning every loco has gone smoothly through the Hornby trainset point.  The arrival this morning of a mint Bachmann class 20 has caused me a lot of grief.  Every time the loco transitted the diverging route on the point with the narrow hood leading,  the loco would derail.  I checked the back to back at 0.570" (around 14.4mm),  however the derailment continued as I believed that the narrow hood bogie was fouling on the footplate and steps.  After modifying the body slightly to avoid any contact as the bogie moved about its pivot, the derailment continued.  There was no issue with the cab end entering the point diverging route.

 

With the loco moving slowly through the point I noticed that the narrow hood end leading axle would jump as it approached the frog entry,  basically before the bogie had barely started to swing.  A few seconds with a file on the entry to the frog totally fixed the situation with the loco transitting the diverging route on the frog at speed with no evidence of derailment.  I assumed that as every other purchase had successfully moved through the point that the loco was to blame,  however it seemed that a small burr on the track had caused the loco to derail.

[roundhouse]

I have had a similar issue after cutting flexitrack and joining to an N scale turnout on my test circuit. All my UK and USA outline locos would run through without any issue. However when running my 009 Heljan Manning and Wardle's they would derail despite them running fine (after numerous modifications) on my 009 layout that has Peco mainline 009 track. After using a file on the cut rail to remove a small burr, they ran through fine from then on.

[The Johnster]

Good point, and an excellent piece of detective work!  Another thing to check is debris finding it's into flangeways, which in my experience is fussy about which locos and stock it will affect.  I have a set of brightly coloured (hence easy to find) pound shop children's nylon bristle paint brushes that are u/s for painting with unless you want that effect, but brilliant for sweeping flangeways, especially on newly ballasted track!