## 3 Experimental Results and Discussions  
Intense traffic places a faster deterioration on the vehicle's braking system, leading to premature wear of the brake disc and pads. Moreover, limited situations, such as sudden and strong braking, contribute frequently to the destruction of the braking system. Studies have shown that, on average, the lifespan of brake pads is between 40,000 and 100,000 km. The range is relative, considering the fact that the life of the brake pads is also influenced by the number of actuation of the brake pedal. Drivers who drive in urban areas \begin{table}
\begin{tabular}{l c c} \hline \hline
**Parameters** & **Axle 1** & **Axle 2** \\ \hline Wheel mass (of front and rear) on the left, kg & 473 & 267 \\ Wheel mass (of front and rear) on the right, kg & 473 & 267 \\ Axle mass, kg & 946 & 534 \\ Total mass of the vehicle, kg & 1566 \\ Mileage, km & 115,477 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameters of the vehicle under test. are recommended to change their brake pads every 40,000 km, while drivers who drive outside urban areas are recommended to change them every 100,000 km. After installing a new set of pads, the vehicle was subjected to a set of tests on the brake system test stand (although the brake discs (from cast iron) showed little signs of wear, scratches, and rust on the contact surface). Along with changing the pads, the brake fluid was also replaced, so that the efficiency of the braking system was as high as possible. The efficiency of the tested vehicle's braking system was established during road tests and on the test stand. The test conditions took into account the condition of the vehicle in terms of mass, which must be the one prescribed for each type of test; the tests were carried out at the speeds prescribed for each type of test, namely at a multiple of 5 km/h; the force applied to the braking system to achieve the prescribed efficiency must not exceed the maximum force provided; the road must be dry and have a surface that provides a coefficient of adhesion in the range of 0.8-0.9; tests should be performed when there is no wind to affect the results. In Figure 4a, the scratches on the brake disc surface are shown. Traces of wear caused by the use of defective brake pads can be observed, which leads to the destruction of the brake disc. Figure 4b, shows the degradation of the brake disc caused by the presence of rust. After removing the brake pads, the degree of wear can be observed, compared to a set of new brake pads, as well as the signs of wear and detachment of the friction material. These aspects are presented in Figures 5 and 6. To determine the degree of wear of the pads on the front axle, a special thickness measuring system was used (Figure 7). The thickness of the friction material of a new pad was 13 mm (see Figure 7a), and after the brake pad has been worn, the system indicated an average thickness of 10 mm (see Figure 7b), thus resulting in average wear of 3 mm after 18,664 km traveled. For rear axle brake pads, the friction material thickness of a new pad was 10 mm, and after they have been used, the measurement system indicated a thickness of 7 mm, thus resulting in wear of 3 mm after the 18,664 km traveled (see Figure 7b). It is surprising, knowing that the front brakes are more demanding than the rear ones. The explanation would be that the testing was done under the same conditions both for the front and rear brakes. Thus, the discs and pads were replaced with new ones. The brake fluid was also replaced, and the brakes were aired out, respectively, in order to obtain optimal pressure in the braking system. Following the replacement of the pads, a series of tests of the braking system were carried out to determine its efficiency, the braking force, as well as other parameters concerning the entire braking system. Figure 4: Scratches and wear traces present on the brake disc surface (**a**); brake disc with traces of rust (**b**).