A friction assembly includes a brake head including a secondary channel, a friction plate including a primary channel and adapted for assembly to the brake head, at least one connecting ring inserted into the secondary channel and establishing a connection with the primary channel when the primary channel is aligned with the secondary channel, and a connector block which is fixed on the brake head. The block has a cavity connected to a suction device, and connected to the secondary channel by a hole, and the at least one ring is removably mounted on a connecting plate, the entity formed by the connecting plate and the at least one connecting ring being removably secured to the brake head.