Please ignore my mistake on reply.
I haven't examined the Details West derail kit, nor find it pictured on their website. Nevertheless, it sounds like you installed it improperly or the model is too large. You may need to file the parts so there is proper clearance, particularly the gap between rail and derail. Model wheels have deeper/wider flanges than the prototype.
If the derail is set like this, the cars are supposed to derail, and if properly installed, direct the car in the direction of least danger/harm:
(Gee. The tie plates and spikes on this track are barely visible even at this short distance.)
Mark
I've made my derail not like the prototype, not sliding but turning. No problems with cars at FREMO meetings. The only problem was a few guys overrun it!!! And it worked !!
More at my Diamond Valley site.
Wolfgang
Pueblo & Salt Lake RR
Come to us http://www.westportterminal.de my videos my blog
I purchased and assembled a derail kit produced by Details West. I wanted to add this detail item to a new spur that I'd added to my layout. I installed the derail, and it looked pretty good...but then I ran into trouble. After installing the derail I test operated several model rail cars on the spur to make sure all was okay. To my dismay I found that the axles or detail parts on the trucks of several cars would not clear the derail. The cars in question were produced by Intermountain. Any suggestions as to what to do about the deail so it will clear the trucks and axles? It's not a huge crisis if I have to remove the derail, but it sure would be a nice scenic detail. All advice will be appreciated. Thank you!