رگڑ کی جوڑی کا لباس بریک اسٹیٹ کے خراب ہونے کی بنیادی وجہ ہے۔ Friction works in the form of dynamic fit, and the material loss of friction surface gradually increases with the increase of the number of uses. When the wear accumulates to a certain extent, the characteristic parameters of dynamic friction pair gradually change and the working capacity is reduced. دوسرے مماثل حصوں کا لباس بھی رگڑ کے جوڑے کے لباس کو متاثر کرتا ہے۔ For example, the uneven wear of the brake CAM affects the lift of the CAM, which in turn affects the displacement of the shoe until it affects the contact between the friction material and the pair.