# Parametric Selection of Optimized Epicyclic Gearbox Layouts for Wind Power Plant Applications
## 4 Results
### Data Presentation
#### 4.2.2 Three-Carrier Gear Train Data
A more detailed overview of the properties of these gearsets is found in Figure 12.  
It is evident that minimal mass is achieved with gearset S16 NW(E) with the combination of \(t_{\rm I}=3\) and \(t_{\rm II}=2.8333\) for \(i=0.08\), while gearset S26 NE(W) achieves this with \(t_{\rm I}=2.6667\) and \(t_{\rm II}=2.6667\) for \(i=-0.08\). Data from Table 11 suggests that S16 NW(E) is a clear winner according to the criterion of minimal mass, while gearset S26 NE(W) is the best solution from Table 11 as it offers a smaller maximum ring gear reference diameter than S16 EW(N) even though it is some 30 kg heavier. According to the data from Tables 11 and 11, the S16 NW(E) and S26 NE(W) gear trains also provide the best solution from the standpoint of minimal largest ring gear reference diameter in the category of \(\mid\!i\!\mid=0.08\). A more detailed overview of the properties of these gear trains is found in Figure 13.  
Table 110.0 (**a**) Relationship of the efficiency of the S16 NW(E) gearest to the ideal torque ratios \(t_{\rm I}\) and \(t_{\rm II}\) for \(i=0.02\); (**b**) relationship of the efficiency of the S16 EW(N) gearest to the ideal torque ratios \(t_{\rm I}\) and \(t_{\rm II}\) for \(i=-0.02\). The minimal largest reference diameter is achieved with gearset S16 NW(E) with the combination of \(t_{\rm I}=3\) and \(t_{\rm II}=2.8333\) for \(i=0.08\), while gearset S26 NE(W) achieves this with \(t_{\rm I}=2.6667\) and \(t_{\rm II}=2.6667\) for \(i=-0.08\). Analysis of the data from Tables A9 and A10 demonstrates that S16 NW(E) and S26 NE(W) provide the best solution even according to the additional efficiency criterion, even though other solutions with acceptable efficiencies exist. According to the data from Tables A11 and A12, the S16 NW(E) and S26 NE(W) gear trains provide the best solution from the standpoint of maximum efficiency in the category of \(|i|=0.08\). A more detailed overview of the properties of these gear trains is found in Table 110.1  
Table 110.2 (**a**) Relationship of the mass of the S16 NW(E) gearset to the ideal torque ratios \(t_{\rm I}\) and \(t_{\rm II}\) for \(i=0.08\); (**b**) relationship of the mass of the S26 NE(W) gearset to the ideal torque ratios \(t_{\rm I}\) and \(t_{\rm II}\) for \(i=-0.08\). Table 110.3 (**a**) Relationship of the minimal largest ring gear reference diameter of the S16 NW(E) gearset to the ideal torque ratios \(t_{\rm I}\) and \(t_{\rm II}\) for \(i=0.08\); (**b**) relationship of the minimal largest ring gear reference diameter of the S26 NE(W) gearset to the ideal torque ratios \(t_{\rm I}\) and \(t_{\rm II}\) for \(i=-0.08\). Analysis of the data from Tables A11 and A12 demonstrates that S16 NW(E) and S26 NW(E) provide the best solution according to the criterion of efficiency. The maximum efficiency is achieved with gearest S16 NW(E) with the combination of \(t_{\rm I}\) = 4.3333 and \(t_{\rm II}\) = 1.6667 for \(i\) = 0.08, while this is achieved with gearest S26 NW(E) for \(t_{\rm I}\) = 2 and \(t_{\rm II}\) = 3.5 in the case of \(i=-0.08\). For \(i\) = 0.08, S16 NW(E) is tied with S23 EW(N) regarding efficiency, and even though S23 EW(N) is some 1200 kg lighter, S16 NW(E) has a more favorable maximum ring gear diameter ratio, and, therefore, represents the better solution. For \(i\) = \(-0.08\), S26 NW(E) is a clear winner, as it offers the best efficiency combined with minimum mass. The results are summarized in Table 110.4 Red signs denote the best solution in the category for \(\mid i\mid\) = 0.02, while blue signs denote the best solution for \(\mid i\mid\) = 0.08. It is possible for a gear train to be a multiple best solution as the direction of rotation of the output shaft is not important for this application. The gear trains from Table 2 are shown schematically in Figure 15, and their respective kinematic schemes are provided in Table 110.5  
In the case of a two-stage gear train, S26 EW(N) and S26 NW(E) are tied; however, the recommendation would be to use S26 EW(N) as it is kinematically simpler and does not need hollow shafts to build.