Abstract: The invention relates to a reinforcement device for reinforcing the open slots of a carbon brake disk. According to the invention, each slot is provided both with a U-shaped insert whose two lateral limbs are disposed to face the lateral faces of the corresponding coupling bar, and with two channel-section caps that extend towards each other so as to surround the two lateral limbs of the insert completely, each cap having a free end edge that occupies a plane that is parallel to the corresponding inside face and that, on initial assembly, stands slightly projecting relative to said face, thereby enabling said free end edge to be brought exactly into the plane of said inside face after the brake has been used during a running-in period.