1 general:: Phrase(s): bear down (on someone or something) to press down on someone or something. • Bear down on the pen. You have to make a lot of copies. • Don’t bear down too hard or you’ll break it.
McGrawhill's American Idioms And Phrasal Verbs
2 general:: 1. Press or weigh down on someone or something. For example, This pen doesn't write unless you bear down hard on it. [Late 1600s] 2. Try hard, intensify one's efforts, as in If you'll just bear down, you'll pass the test. 3. Move forward in a pressing or threatening way, as in The ferry bore down on our little skiff. This usage was originally nautical. [Early 1700s]
American Heritage Idioms