*break down*

Definition: for a vehicle to suffer mechanical failure (and for a human to suffer to emotional failure!)

*This verb has more than one meaning.

E.g.1:  I could not believe it, this morning on the way to work my car suddenly broke down.
E.g. 2:  Breaking down on the motorway can be extremely hazardous as well as very annoying!

*This verb can not be separated.