The proportion of the different components varies depending on the type of lining and is ultimately determined by the required performance of the brake lining material. Brake linings are classified into three main groups (Table 1) on the basis of the proportions of the above components present in their structure and each is suited to different applications. Experimental results indicate that variations in brake lining formulations exert a major influence on both physical and chemical properties of PM generated through brake abrasion.