The fulcrum of this thesis is the study of the Static Transmission Error of two meshed gears, in this specific case cylindrical gears, which is the main proponent of the problems related to noise, vibrations and roughness. Starting from the aforementioned premises, in this thesis, a careful analysis on different Static Transmission Error values was obtained through a comparison between the measurements obtained from a previously designed test bench and a dedicated software called GeDy TrAss. First of all it is described what type of phenomenon is the STE, after which the test bench is summarized in all its characteristics describing the improvements made with respect to the first configuration.