Social Studies help! Easy question, just need ideas! Will give points to best answer!?

We are studying american government and separation of powers. He gave us an example of a bike. The brakes represent the judicial branch because the keep things in check and slow things down. The wheels represent the executive branch because they give direction and motion. The drivetrain represents the legislative branch because it propels the whole. I need to "create a similiar ogy of the separation of powers. be sure to explain how all the parts work separately to make the whole thing work and relate to the concept of separation of power." Thanks! I need an idea to get started, the more ideas the better! Thanks!