## 3 Results and Discussion  
An analysis of the dependence diagrams (Figure 12) developed as a result of the experimental studies of the test device for evaluating the suitability of potato varieties and hybrids for mechanized harvesting makes it possible to conclude that the maximum force action (F = 20.3 N) on potato tubers occurs when the tuber is transferred from the pin hummock onto the work surface of the separating drum within the time interval of 9 to 11 s.  
This circumstance should be explained by the fact that in the course of the data logger, travel along the separating surfaces of the test device for evaluating the suitability of potato varieties and hybrids for mechanized harvesting, irrelevant of the travel speed of the pun hummock, the belt is lifted along the vertical plane due to the action of separation intensifier. Figure 12: Force action of the work surface of the pin hummock on potato tuber: (**A**)—annular travel speed of roller separating surface \(V_{EL}=3.6\) km/h; (**B**)—annular travel speed of roller separating surface \(V_{EL}=5.0\) km/h; (**C**)—annular travel speed of roller separating surface \(V_{EL}=6.4\) km/h. The intensifier is used in the design of the machine in order to create additional torque for the purpose of orientating the tuber towards the slot and increase the time of the tubers' interaction with the separating surface. The interpretation of the graphical dependencies presented in Figure 9 obtained during experimental studies confirms that the greatest force effects (F = 18 N) on potato tubers are observed in the time range of 10-11 s, as well as at 14 s of separation of the tuberous heap, which corresponds to the finding of tubers and the effect of the working elements of the harvester in real conditions during the transfer of the separated products from the bucket elevator to the hedgehog and on the bulkhead table, respectively. In addition, an increase in the force effect during the separation of the tuberous heap is observed during the transition from the digging working body to the main elevator up to 14 N (t = 2 s), as well as directly at the main elevator (F = 14 N, t = 3 s). The above factors cause the vertical component of force action of the separation intensifier to increase between the operating components of the pin hummock and potato tubers, resulting in the increase in the force action on tubers and thus in increased damage. Analyses of the results of the experimental studies of force action on a potato tuber by work elements of the test device for evaluating the suitability of potato varieties and hybrids for mechanized harvesting demonstrated that the measured value varies within a wide range, depending on the location of the tuber at the functional element (variation coefficient \(\
u\) = 26.9%, mean square deviation \(\sigma\) = 5.52). A time interval of 8.5 to 9.5 s accounts for the highest force action (of up to 22 N) on the potato tuber (Figure 6); here, the mean square deviation and the variation coefficient are \(\sigma\) = 5.7 and \(\
u\) = 24.8%, respectively. As a result of the variance analysis of the two-factor experiment, the following main statistical characteristics of the experiment were obtained:  
- Variance of the experimental error, \(S_{y}^{2}\) = 7;  
- Standard error \(S_{bk}\) = 1.16;  
- error variance, \(S_{bk}^{2}\) = 1.36;  
- Dispersion of reproducibility, \(S_{repr}^{2}\) = 16.33;  
- Dispersion of inadequacy, \(S_{inadequ}^{2}\) = 1.368;  
- Tabular value of the t T-criterion, \(t_{\text{T0.05}}\) = 4.02;  
- Value of the tabular t-criterion, \(t_{\text{0.05}}\) = 3.66;  
- Tabular value of the Fisher criterion at 5% significance level for the resulting equation, \(F_{\text{T}}\) = 5.32;  
- The calculated value of the Fisher criterion at the 5% significance level for the resulting equation, \(F\) = 2.2.