This series of loss-of-power brake must operate oil-free to avoid affecting torque; it can be horizontally installed, and vertical installation is permitted in certain low-speed applications. The square core (keyway sleeve) must be axially fixed on the shaft. When the brake is de-energized, the spring pushes the armature and friction disc, clamping the friction disc between the clamp and armature to achieve braking. During installation, ensure that the friction disc can slide freely on the square core (keyway sleeve), and ensure the perpendicularity of the shaft to the mounting surface, meaning that when the brake is energized, the friction disc can rotate freely between the armature and the clamp without any noticeable noise or damping.