The term REVOLVING PART can be broken down into three crossword solutions: ROTOR (5 letters), ROTATOR (7 letters), and CAM (3 letters). A ROTOR is a rotating part of a machine, such as an electric motor or generator, that is used to convert energy into motion. A ROTATOR is a device that is used to rotate an object around its axis. Finally, a CAM is a rotating or sliding piece in a mechanical linkage used to transfer motion from one part to another. All three of these terms refer to parts that are designed to move in a circular motion.