Oscillations in magnitude of the torque applied to an axle along a kinematic cycle produce variations in turning speed, which can cause machine malfunction. A flywheel is a rotating mass that is used to store energy, so that it reduces the aforesaid oscillations. It stores mechanical energy when the input torque is higher than the requirement and releases it when the resistant torque is more than the input one. The permissible variation in speed depends on the machine. In this chapter, we will study how to design a flywheel that absorbs such torque oscillations to achieve the desired regularity.