The film *Spinning Levers* explores the fundamental mechanics of levers and gears, illustrating their role in various everyday applications and in the complex workings of a car’s transmission.

When you push or pull with a simple machine, you are applying a force and doing work. And, if you get more force out of a machine than you put into it, then that machine has a mechanical advantage.

• Planetary units with helical gears, rather than spur gears, have higher torque capacity and run quieter. • Different manufacturers measure and rate backlash in different ways. • Software tools for ...