Periodic running machines, such as linkages and cam-follower mechanisms, are usually designed considering a constant drive speed. However, in high speed machines, the required torque to drive the input shaft at constant speed exhibits a very high periodic fluctuation, hence massive motors are required to drive even small loads. This paper, starting form a review of the available literature, presents a theoretical framework to the problem of input torque balancing, and it defines a methodology for the synthesis of balancing mechanisms with the task to fully compensate the load variations due to a periodic torque.