Almost all of the mechanisms and machines discussed so far were examples of planar problems. There are, however, many important machines and mechanisms with motions that are not planar. Gyroscopes and all machines that use gyroscopic effect for navigation can be listed as examples. Chapter 15 covers the basic principles of three-dimensional dynamics, including Euler’s equations of motion and equations for parallel-plane motion. A discussion about gyroscope and the gyroscopic effect concludes this chapter.