We need to get in gear [=get going] if we want to finish this project on time.要想按时完成这个项目，我们需要更有效率地工作。

She finally got her career in gear. [=finally started to be successful in her career]她的事业终于步入了正轨。

(US, informal + impolite) He angrily told him to get his ass in gear. [=to get going, to start moving or doing something much more quickly]他生气地叫他赶紧开始干活儿。