1.
If someone or something bears down on you, they move quickly towards you in a threatening way.
A group of half a dozen men entered the pub and bore down on the bar...
= advance
PHRASAL VERB: V P on n, also V P
2.
To ~ on something means to push or press downwards with steady pressure.
The roof support structure had collapsed and the entire weight was bearing down on the ceiling.
PHRASAL VERB: V P on n, also V P