The invention relates to an electromagnetically ventilating spring-pressure brake for mounting on the driving disk (15) or the driving disk shaft (16) of already existing elevators, which are operated with cables passing over a driving disk. The external-mounted brake (1) is situated concentric to the central axis of the driving disk (15) or driving disk shaft (16) on a separate base (23) of the structure on the free side (i.e. opposite the driving side) of the driving disk (15) and is fastened in a stationary and rotationally fixed manner. The rotor (5) of the brake (1) is connected in an essentially rotationally fixed manner to the free end of the driving disk (15) or of the driving disk shaft (16) in order to transmit the braking torque of the external-mounted brake to the driving disk (15).