Here we can see the complete construction of the truck disc-brake. On the left, protected by plastic sleeves, are the wheel bolts with the hub for the wheel mountings. then, we can see the (starting to rust) internally cooled brake disc with the brake-pads on the left and the right. Following on the right, the diverter mechanism, the membrane cylinder and the air pressure connection (also covered by a protection cap).

The brake discs are designed for a durability of approx. 500.000 km., if one assumes a medium amount of stress and long distance haulage. In the same period of time, approx. three sets of pads are worn out. In contrast to brake-drums, which are turned out on a lathe, discs are replaced when worn out. The condition of the pads can generally be seen without removing the wheel. Although electronic measuring can be helpful, it cannot however, recognise one-sided wear and tear of only one of the two pads.