A brake device (1) is for use with a cable-operated door (3), such as garage doors (3) and the like. The device (1) is intended to reduce the risk of the door (3) falling, or at the very least slow down its descent, in the event of a failure in the counterbalancing mechanism of the door (3), which is generally represented by a loss of tension in a given tensioned cable (5) operating the door (3). The brake device (1) includes a support bracket (9), and a guiding assembly (15) and a braking assembly (17) mounted onto the support bracket (9). The braking assembly includes a swivel component (18) having a braking arm (19) and a lever portion (20), the lever portion cooperating with the tensioned cable (3) so that in the event of the loss of tension in the cable (5), the braking arm (19) is urged onto an adjacent rail (7) via a biasing spring (21) for anchoring a knife (45) of the braking arm (19) into the rail (7) and stopping, or at the very least, slowing down the descent of the door (3), with respect to the rail (7).