## 3 Analysis of Joint Loading Under Different Drive Mechanism Variants
\begin{table}
\begin{tabular}{l l l l l l l l l} \hline
**Variant** & \(D_{\mathbf{3}}\) & \(d_{\mathbf{3}}\) & \(b_{\mathbf{3x}}\) & \(b_{\mathbf{3y}}\) & \(a_{\mathbf{3x}}\) & \(a_{\mathbf{3y}}\) & \(c_{\mathbf{3p}}\) & \(c_{\mathbf{3k}}\) \\ \hline  & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** \\ \hline V.001 & 125 & 90 & 0 & \(-\)524 & 1655 & \(-\)129 & 1340 & 2058 \\ V.108 & 150 & 100 & \(-\)16 & \(-\)362 & 1360 & \(-\)86 & 1179 & 1618 \\ V.135 & 125 & 90 & 137 & \(-\)506 & 1764 & \(-\)115 & 1340 & 2073 \\ \hline \end{tabular}
\end{table} 
Table 1: Selected generated variant of the arm drive mechanism. \begin{table}
\begin{tabular}{l l l l l l l l l l} \hline
**Variant** & \(D_{\mathbf{4}}\) & \(d_{\mathbf{4}}\) & \(b_{\mathbf{4x}}\)/\(b_{\mathbf{4y}}\) & \(s_{\mathbf{5x}}\)/\(s_{\mathbf{5y}}\) & \(a_{\mathbf{6x}}\)/\(a_{\mathbf{6y}}\) & \(a_{\mathbf{4x}}\)/\(a_{\mathbf{4y}}\) & \(b_{\mathbf{6x}}\)/\(b_{\mathbf{6y}}\) & \(c_{\mathbf{6}}\) & \(c_{\mathbf{4p}}\) & \(c_{\mathbf{4k}}\) \\ \hline  & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** \\ \hline V.001 & 150 & 100 & 206\(/\)\(-\)209 & 1703/577 & 13/369 & \(-\)182/676 & 0\(/\)\(-\)751 & 756 & 1340 & 1897 \\ V.108 & 180 & 125 & 236\(/\)\(-\)83 & 1703/577 & \(-\)13/299 & \(-\)75/835 & 0\(/\)\(-\)840 & 637 & 1397 & 1727 \\ V.135 & 150 & 100 & 206\(/\)\(-\)207 & 1703/577 & 12/354 & \(-\)196/725 & 0\(/\)\(-\)751 & 756 & 1393 & 1862 \\ \hline \end{tabular}
\end{table} 
Table 2: Selected generated variant of the bucket drive mechanism. rod diameters: \(D_{3}/d_{3}=125/90\) mm and \(D_{4}/d_{4}=150/100\) mm) compared to the variant V.108 (\(D_{3}/d_{3}=150/100\) mm and \(D_{4}/d_{4}=180/125\) mm). Each variant of the drive mechanism was analyzed based on the forces generated during the material loading process. The components of the loading resistant force vector \(\mathbf{W}\) representing the material loaded by the bucket during the loader's manipulation task were determined using the Discrete Element Method (DEM) [39; 40; 41]. The forces of loading resistance were determined using a bucket with a nominal capacity of 2.7 m\({}^{3}\) and a width of 2750 mm. From the EDEM 2021 software library, a material representing gravel was selected. The material properties used in the simulation were as follows: material density of 1934 kg/m\({}^{3}\), coefficient of restitution of 0.75, coefficient of static friction of 0.32, and coefficient of rolling friction of 0.2. These values correspond to the typical behavior of coarse granular materials and were used as input parameters for the EDEM simulation environment. The bulk material consisted of 100,000 discrete particles whose sizes were generated according to a normal distribution, constrained within a range of 51.5 mm to 71.5 mm. These particles collectively formed a bulk material with an approximate volume of 30 m\({}^{3}\), distributed on a horizontal surface. Based on the simulation using the Discrete Element Method (DEM), the resistance force vectors during the loading operation were determined. Figure 3 shows the \(W_{x}\) and \(W_{y}\) components of the resistance force as a function of time during the simulated loading operations. The results are presented for two types of bucket penetration trajectories into the material: (a) stepwise (\(W_{xstep}\), \(W_{ystep}\)) and (b) parabolic (\(W_{xpart}\), \(W_{ypart}\)). The duration of the simulated loading operation cycle was 6 s for the stepwise trajectory and 7 s for the parabolic trajectory. For assessment of the influence of manipulator mechanism parameters on the tribological characteristics of mechanism revolute joints, three selected variant solutions were analyzed using numerical dynamic simulation in MSC Adams. The models shared identical parameters for the \(L_{i}\) kinematic chain members but differed in the manipulator mechanism configurations.