Abstract: A spool may include a drum rotatably supported on an axle shaft and flanges integrally formed with opposite ends of the drum. The drum has a continuous groove on the outer surface of the drum to guide the movement of the safety wireline. Both of the flanges may include an opening, internal threads circumscribing the opening, and a plurality of mechanical brakes. Each of the mechanical brakes may include a rotor rotatably supported on the axle shaft of the spool and a pawl arranged within the opening. The pawl is pivotally linked to the rotor such that when the rotation of the axle shaft is in a direction and at a rotation speed that exceeds a threshold then the pawl is moved by centrifugal force and engages with the internal threads circumscribing the opening and does not permit the spool to rotate.

Abstract: A spool may include a drum rotatably supported on an axle shaft and flanges integrally formed with opposite ends of the drum. The drum has a continuous groove on the outer surface of the drum to guide the movement of the safety wireline. Both of the flanges may include an opening, internal threads circumscribing the opening, and a plurality of mechanical brakes. Each of the mechanical brakes may include a rotor rotatably supported on the axle shaft of the spool and a pawl arranged within the opening. The pawl is pivotally linked to the rotor such that when the rotation of the axle shaft is in a direction and at a rotation speed that exceeds a threshold then the pawl is moved by centrifugal force and engages with the internal threads circumscribing the opening and does not permit the spool to rotate.