break down
With or without an object
Stop working (a machine or vehicle)
Our car broke down on the motorway.
Lose control of your feelings
She broke down in tears when she heard the news.
With or without an object
It can be used with no object, and it can also take one. With an object it is usually separable: turn the volume up, turn it up.
The particle: down
This verb belongs to the group ‘breaking and closing’.
Others in the group: close down, shut down.
Practise it
Add it to your daily practice or see every verb with down.
Further reading: break down on Wiktionary (CC BY-SA).