Slid afhænger af friktionsbetingelserne og friktionstilstanden. The friction material is mostly in the form of dry friction, and this friction condition without lubrication is a harsh condition for the friction pair, which will inevitably cause wear and increase the matching gap, and affect the braking performance. And under normal circumstances, the wear of the friction pair is uneven wear, and the wear gap caused by all wear is also uneven, which is prominent on the drum brake. Friktionens ikke-ensartethed ændrer fordelingen af ​​bremsetrykket og øger det ikke-ensartede slid af friktionspar. In addition, the friction heating of the braking process and the dust of the operating environment into the friction pair will cause the process of driving wear, which is thermal wear, abrasive wear, adhesive wear, fatigue wear and so on play a role at the Samme tid, det vil sige, er slid uundgåelig. However, the amount and speed of wear can be controlled, because the speed of wear depends on the number and frequency of use, the intensity of use, the use environment and the level of use.