## 3 Results and Discussion  
### Reliability Analysis of the Components That Have the Most Defects  
In order to improve the efficiency of the maintenance activities of the technological equipment in aggregate mining quarries, the actual operating times (within a period of three years) between two failures are measured, namely the repair times (duration of the tooth replacement activity) for the bucket teeth of a Liebherr 944 L excavator (Table 2) and for the Volvo L220 E front loader (Table 3). The results, totaling 26 for the Liebherr 944 L excavator (Table 2) and 47 for the Volvo L220 E front loader (Table 3), are presented in the table in ascending order. The data thus obtained were analyzed with the Relyence Weibull software (produced by the Relyence Corporation) to obtain the reliability and maintainability variability of the bucket teeth from the mentioned machines. The Relyence Weibull software initially ranks the goodness of fit of different distribution laws (Figures 6-9) to the studied data (Tables 2 and 3). \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Time** & \multicolumn{10}{c}{**Value**} \\ \hline Operating times between two failures (hours) & 18 & 24 & 35 & 36 & 37 & 42 & 43 & 48 & 64 & 65 \\  & 66 & 67 & 72 & 73 & 78 & 96 & 108 & 120 & 126 & 138 \\  & 140 & 162 & 168 & 174 & 198 & 222 & & & & \\ \hline  & 40 & 60 & 60 & 60 & 60 & 60 & 60 & 60 & 60 & 60 \\ Repair times (minutes) & 60 & 60 & 60 & 65 & 65 & 65 & 70 & 70 & 75 & 75 \\  & 80 & 80 & 80 & 80 & 85 & 85 & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Values of operating time between failures and repair times of the bucket teeth of the Liebherr 944 L excavator. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Time** & \multicolumn{10}{c}{**Value**} \\ \hline  & 7 & 7 & 7 & 14 & 14 & 14 & 14 & 14 & 20 & 21 \\ Operating times between two failures (hours) & 21 & 26 & 27 & 28 & 28 & 29 & 35 & 37 & 42 & 44 \\  & 48 & 55 & 56 & 63 & 65 & 69 & 70 & 72 & 76 & 77 \\  & 78 & 79 & 83 & 105 & 107 & 114 & 118 & 127 & 130 & 149 \\  & 160 & 178 & 211 & 227 & 347 & 533 & 538 & & & \\ \hline  & 120 & 180 & 180 & 180 & 180 & 180 & 180 & 190 & 200 & 205 \\  & 220 & 220 & 230 & 230 & 230 & 240 & 240 & 240 & 240 & 240 \\ Repair times (minutes) & 240 & 250 & 260 & 260 & 260 & 260 & 260 & 260 & 270 & 270 \\  & 270 & 270 & 290 & 290 & 300 & 300 & 300 & 300 & 300 & 300 \\  & 310 & 310 & 320 & 330 & 360 & 450 & 840 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Values of operating time between failures and repair times of the bucket teeth of the Volvo L220 E front loader. Figure 8: Classification of the distribution law acceptance for the failure of bucket teeth on the Volvo L220 E front loader. Figure 6: Classification of the distribution law acceptance for failure of the bucket teeth on the Liebher 944 L excavator. Figure 7: Classification of the distribution law acceptance for changing bucket teeth on the Liebher 944 L excavator. The assessment of actual operating times until bucket tooth replacement for both the excavator and the loader was obtained by analyzing the operating times between two failures, namely:  
* By adopting the 3-Parameter Weibull distribution law (Figure 6) for the operating times between two failures of the Liebherr 944 L excavator's bucket teeth, we were able to assess the evolution of failure times. Similarly, we used the Normal distribution law (Figure 7) to analyze the evolution of repair times for the teeth;
* By adopting the Lognormal distribution law (Figure 8) for the operating times between two failures of the Volvo L220 E front loader's bucket teeth, we were able to assess the evolution of failure times. Similarly, we used the 3-Parameter Weibull distribution law (Figure 9) to analyze the evolution of repair times for the teeth.