## 3 Results and Discussion
### Driven Drum End Surface Radial Weight Dynamic Balance Effects  
As shown in Figure 4, the driven drum end surface radial weight dynamic balance was tested. The mass of 161.3 g was added to the weight holes in the 60\({}^{\circ}\), 120\({}^{\circ}\), 180\({}^{\circ}\), 240\({}^{\circ}\), 300\({}^{\circ}\), and 360\({}^{\circ}\) directions of the end of the threshing drum. The unbalance amount of the threshing drum was measured at different rotation speeds. The test data was shown in Table 3.  
Since the threshing drum rotated counterclockwise, the chain drive was loose on the upper side and the tight side was on the lower side. There was a chain pulling force on the sprocket on the tight side. The loose side had a certain impact force on the sprocket. Especially when the transmission chain was not tight enough, the lateral vibration of the chain was obvious. These forces were all acted on the rotating shaft through the transmission system, which was equivalent to the chain drive exerting a series of imbalances of different sizes and phases on the rotating shaft. The phase change area was shown in Figure 9. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Weight Holes**} & \multirow{2}{*}{**Item and**} & \multicolumn{4}{c}{**Threshing Drum with Different Rotation**} \\ \cline{3-6}  & & **600 rpm** & **700 rpm** & **800 rpm** & **900 rpm** & **1000 rpm** \\ \hline \multirow{2}{*}{60\({}^{\circ}\)} & Amplitude (mm/s) & 0.532 & 0.426 & 0.486 & 1.16 & 1.716 \\  & Phase (\({}^{\circ}\)) & 222 & 275 & 319 & 27 & 35 \\  & Amplitude (mm/s) & 0.431 & 0.502 & 0.735 & 1.869 & 2.662 \\  & Phase (\({}^{\circ}\)) & 146 & 135 & 127 & 121 & 112 \\  & Amplitude (mm/s) & 0.22 & 0.382 & 0.538 & 2.028 & 2.868 \\  & Phase (\({}^{\circ}\)) & 135 & 124 & 102 & 114 & 123 \\  & Amplitude (mm/s) & 0.383 & 0.513 & 0.972 & 1.487 & 2.725 \\  & Phase (\({}^{\circ}\)) & 181 & 173 & 161 & 159 & 149 \\  & Amplitude (mm/s) & 0.631 & 0.483 & 0.661 & 1.271 & 1.863 \\  & Phase (\({}^{\circ}\)) & 186 & 209 & 219 & 180 & 163 \\  & Amplitude (mm/s) & 0.618 & 0.465 & 0.622 & 0.861 & 1.094 \\  & Phase (\({}^{\circ}\)) & 214 & 256 & 268 & 341 & 30 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Unbalance of each phase point with different threshing drum rotation. Figure 8: Unbalanced phase relationship diagram. Because the chain drive affected the drum within the wrap angle to varying degrees, the drum was unbalanced. The unbalance was non-uniform and varied in size. Therefore, all the unbalances generated in the chain transmission process were equivalent to two unbalanced quantities, which were the unbalance of the tight edges and the loose edges. At the same time, the size and position of the wrap angle of the chain drive would directly affect the phase of the two equivalent unbalanced masses. The vibration generated by the chain drive at the critical point of the wrap angle was large. So the phase of the element with a large force near the two critical points was taken as the phase of the equivalent unbalance amount. [PERSON] et al., (2016) had shown that as the drum speed increases, the frequency of the lateral vibration of the transmission increased and the amplitude decreased [40]. With the increase of the tension, the frequency of the lateral vibration of the transmission did not change and the amplitude decreased. Changes in the tension of the drive chain and the change in the speed of the barrel were subject to changes in the lateral vibration of the chain drive. That was to say, the magnitude of the equivalent unbalance would vary, which caused the phase of the chain drive unbalance to always change within the wrap angle, rather than being constant. Therefore, the unbalanced phase region was always within the wrap angle range or overlapped with the wrap angle range as shown in Figure 9. This was a good explanation for why the emphasis phase was not always in the unbalanced phase region after the emphasis.