| 摘要 |
A controlled-speed device for lowering passengers and materials on a cable or rope from an elevated structure, using paired banks of alternatively opposed arms, pivotably anchored to a rigid frame, for controllably inducing friction in a cable zigzagging between the tips of the arms by varying both pressure upon and length of arcuate contact with the cable or rope. The device is selectively attached to an elevated structure or descends with the load. The arms are inclined upwardly or downwardly but generally are always inclined toward the incoming portion of the cable. The cable is selectively a single length, a double length, or endless. The tips of the arms have a groove, through which the cable passes, which is covered with a frictional composition or alternatively the cable passes over a roller attached to a brake assembly on each arm. The arms are selectively solid or have a resiliency device for absorbing shocks and minimizing binding forces upon the cable that could cause jerkiness in movement.
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