What could cause overheat/meltdown?

[foxhsu]

We are running on DCC layout. Years ago, I had a MA Dream Space meltdown. I remember it's the end car with light board on it. It looks like the spring overheat and meltdown. 

This weekend, I have Tomix 800(fully light, no decoder) happened, too. The front car was on a turn. The truck melt down and break half, both wheels and half truck lay-down outside the track. When I pick it up, the spring still hot. 

It look like melting down very fast, and dcc didn't detect the short. too. I try to change the truck from other TM 800 truck, it runs ok without heat so far. 

I am not sure what could cause this. 

[roadstar_na6]

Probably the DCC system didn't detect a short circuit and pushing continous 18V(?) through something that's only meant for 12V I can easily understand why it melts down fast when there is a short.

[foxhsu]

BTW, anyone know which part number is for the front truck? Manual didn't show the number. 

[chadbag]

What voltage do you run your DCC at?  Not the expert, but wondering based on @roadstar_na6 reply.  My DCC allows me to set the voltage -- there may be some DCC that is more H0 oriented that has a set voltage of 16v or 18v?

[foxhsu]

I didn't check it yet. I will check next time. It's club layout with digitrax Chef system. 

The wried thing is both wheels and half truck were lay outside the track after the turn when I found it stop moving. It looks like short before/durning the turn.