| 摘要 |
A monodirectional braking mechanism for use with a device for extending and retracting a sheet of material on a roller, the braking mechanism comprising one or more than one housing, one or more than one rotor within the housing, a brake controller connected to the rotor, and an eccentric brake operatively coupled with the brake controller, where the braking mechanism reduces the force or rate, or both the force and rate, of rotation of the roller as the roller is rotated in a second rotation direction but has substantially no effect on the force or rate of rotation of the roller when the roller is rotated in a first rotation direction, and where the first rotation direction is the reverse of the second rotation direction.
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