## 2 Operational Conditions and Examples of Suspension System Damage
The lack of the driver's reaction, such as speed reduction, or indiscriminate driving into the cavities in the pavement, has considerable influence on the possible damage to the suspension system components. Vehicle overloading is a frequent, yet unacceptable practice. Sometimes, especially in the case of trucks or delivery vans, drivers cause vehicles to overload to save time. Such situations may also be categorised as factors conducive to the destruction of the suspension system. The factors mentioned above warrant the conclusion that the suspension system is one of the systems most exposed to the direct influence of external factors. This, in turn, translates into the ease of damage or wear of the various components in the system. The least durable components in the suspension system are the rubber and metal/rubber parts. Rubber components become oxidised in a natural process, which leads to the loss of flexibility and brittleness, resulting in a mesh of cracks or scratches. The factors discussed earlier further accelerate this process and may cause the deformation of components. Such components then only need to be replaced as they may be a cause of a road incident. The most common form of degradation of metal suspension components is corrosion. That phenomenon is easy to diagnose during vehicle inspections as it is not necessary to dismantle the various components to identify corrosion centres. Figure 3 shows examples of extreme damage to a suspension system with visible corrosion centres, as well as an example of fatigue cracking in one of the system components. All that damage was diagnosed during a periodic vehicle inspection at a diagnostic station. If the vehicles had not been near the expiry of their road worthiness approval, the drivers would probably not have come to the diagnostic station and they would have continued to operate their vehicles. The consequences of vehicle operation in such a technical condition could be tragic. The computer simulation carried out further in this article will be the best example to illustrate the effects of the operation of a vehicle in which the deterioration processes of the suspension system components were taking place. The driver may have been unaware of the vehicle's condition, which led to fatigue wear and the left front wheel having been torn away, resulting in a road incident. Figure 3: _Cont_. Corrosion is a phenomenon that tends to develop continuously and regularly, especially when the component is not properly protected. This is why preventive maintenance of the suspension system is so important. The operation conditions of the system are conducive to the destruction of corrosion protection, thus making the components even more susceptible to wear and tear. A vehicle driven on a degraded roadway pavement or roads of poor standard generates vibrations that create gaps between the components, allowing impurities to penetrate the system, with such penetration being also responsible for accelerated corrosion processes. Regular operation of the system under such conditions will result in the formation of cracks which, over time, will turn into fatigue cracks, causing the destruction of the component. In addition to corrosion noted on vehicle suspension system components, wear of a tribological nature is also noticed [24]. However, this is difficult to identify because it occurs at the interface between the components. To identify such wear, it would be necessary to disassemble the system and submit it to observations. Due to the time-consuming and complicated nature of the process, however, it is customary not to disassemble the suspension system during operation without a clear indication to do so. The technical inspection procedure at diagnostic stations does not provide for such disassembly, either. Unintentional neglect of issues related to tribological wear may lead to unserviceability, an example of which is shown in Figure 4.  
A component so worn out as the stabiliser rod shown in the figure may be a cause of an unexpected road incident.