"The AGMA dynamic factor has traditionally been treated as a dynamic ""load"" factor where tooth load is the sum of all of the tooth forces that are applied along the plane of action at any instant in time. Knowing the total load@ however@ says little about the degree of load sharing or the load position on a tooth when the dynamic load is a maximum. Hence@ the dynamic load factor does not directly address the value of either dynamic contact stress or dynamic root stress; quantities that a gear designer should be more interested in. This paper's main focus is the prediction of dynamic root stresses. The approach presented in this paper is a relatively simple methodology that does not use finite elements. The method merges the capabilities of a sophisticated load distribution and dynamic excitation prediction method with a time domain gear dynamics simulation. Because a time integration type of simulation is used@ the method can handle both steady state and transient inputs. Inputs that are possible include tooth profile and lead modifications@ misalignments@ and spacing errors. These can take on average values or can have discrete changes applied from tooth to tooth. Examples of the use of some of these errors are provided in this paper."