PURPOSE: To prevent unnecessary high-speed revolution by installing a sliding collar equipped with brake-shoe which revolves together with a taking-up shaft in the brake device for a paper taking-up machine equipped with a torque motor, permitting brake released state to be maintained by means of a spring and a magnetic force.

CONSTITUTION: In normal operation state, a sliding collar 4 is attracted to a magnet 8, and a brake-shoe 6 is apart from the inner wall of a brake drum 7. When taking-up is suspend, torque becomes zero, and the number of revolution of a taking-up shaft 1 tends to rise sharply. When each centrifugal force of brake arms 5a and 5b and of the brake-shoe 6 increases, and exceeds the total value of the tension of a spring 2 and the magnetic force of the magnet 8, the sliding collar 4 is departed from the magnet 8, and the brake-shoe 6 expands outwardly and brakes the revolution of the taking-up shaft 1 in contact with the brake drum 7. Thus, unexpected high-speed revolution can be avoided, and vibration and abrasion can be prevented.