Things have begun developing, unfolding, or progressing. If you're going to act, you have to do it now, but once the wheels are turning, there is no going back. A: "What's the status of our new deployment strategy?" B: "The wheels are turning, we're just waiting for some feedback on how well it's being received."

Progress is being or continues to be made. Typically used in conjunction with verbs like "continue" or "keep." We need to keep the wheels turning with this project or we're not going to make the January deadline. Despite the turmoil in the studio, the wheels continued to turn, and the film eventually saw the light of day 15 years after it first started development.