## 5 Discussion  
The double arc non-circular gear is manufactured by the slow feeding WEDM machine, and the finished product is illustrated in Figure 13. In Figure 13, the numbers 1, 2, and 3 indicate the inner gear ring, planetary wheel, and center wheel, respectively.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Number of Tests**} & \multicolumn{3}{c}{**Test Factors**} & \multicolumn{1}{c}{**P Engagement**} \\ \cline{2-5}  & \(\mathbf{Z_{1}}\) & \(\mathbf{Z^{\prime}{}_{1}}\) & \(\mathbf{Z^{\prime}{}_{2}}\) & **Coefficient** \\ \hline
1 & 27 & 30 & 1115 & 1.294 \\
2 & 27 & 31 & 1116 & 6.486 \\
3 & 28 & 30 & 1116 & 1.394 \\
4 & 28 & 31 & 1115 & 0.965 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Simulation calculation results of orthogonal test.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Test Levels**} & \multicolumn{3}{c}{**Test Factors**} \\ \cline{2-4}  & \(\mathbf{Z_{1}}\) & \(\mathbf{Z^{\prime}{}_{1}}\) & \(\mathbf{z^{\prime}{}_{2}}\) \\ \hline
1 & 27 & 30 & 1115 \\
2 & 28 & 31 & 1116 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Test factors and levels.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Test Factors**} & \multicolumn{1}{c}{**Range**} & **Better Level** \\ \hline \(Z_{1}\) & 2.216 & 28 \\ \(z^{\prime}{}_{1}\) & 2.292 & 30 \\ \(z^{\prime}{}_{2}\) & 2.659 & 1115 \\ \hline \hline \end{tabular}
\end{table}
Table 5: The optimal level and range of each factor.  
After machining the double arc non-circular gears, there is no jamming in rotation after the assembly of the double arc non-circular gears, and the gear backlash at every location tends to be the same; subsequently, the performance is checked on the hydraulic load platform. Table 6 compares the parameters of the prototype and the self-made product at an input pressure of 22 MPa.  
As shown in Table 6, the displacement per revolution and output torque of the self-made double arc non-circular gear are slightly larger than that of the prototype.  
As shown in Figure 14, the emulsion pump is used as the power source, and the emulsion is used as the working medium to make the hydraulic motor rotate under a specific torque; the magnetic powder brake applies a sure torque at the output of the hydraulic engine according to the command sent by the speed collector; the torque speed sensor is installed on the magnetic powder brake to measure the torque and speed data in real-time, which is transmitted to the torque-speed power collector and displayed in real-time through the form of data. The torque characteristic curve at 300-500 RPM is shown in Figure 15.  
\begin{table}
\begin{tabular}{c c c} \hline  & **Prototype** & **Self-Made Product** \\ \hline Module (mm) & 0.75 & 0.75 \\ Tooth Width (mm) & 25 & 25 \\ Displacement (cm\({}^{3}\)/rev.) & 32.9 & 35.1 \\ Torque(N\(\cdot\)m) & 100.0 & 123.1 \\ \hline \end{tabular}
\end{table}
Table 6: Comparison of the performance of prototype and self-made double arc non-circular gear structures.  
Figure 13: Self-made double arc non-circular gear mechanism.  
In Figure 15, the torque characteristic curve displays that the torque of two hydraulic motors decreases as the rational speed increases. A comparison of the output torque of the homemade gear mechanism and the prototype demonstrates that the output torque is similar at the same rotational speed, with a maximum variation of 2.6%. When the operating characteristic curves of the self-made and original double arc non-circular gear mechanisms are compared, it is simple to see that the two gear mechanisms have equal operating performance in the 300 to 500 RMP working range. This shows that the design strategy provided in this paper is extremely practical.