| 摘要 |
A lowering device including a unit which is adapted to slide downwardly at a controlled rate along a rope or other flexible line and which contains a circuitous passage through which the line extends to introduce friction between the line and the unit. In the preferred arrangement, two clamping devices controlled by rotatable collet sleeves are provided at opposite ends of the passage for controllably varying the rate of descent of the unit along the line, and the circuitous passage is formed by a tube contained within a case and surrounded by a mass of resinous plastic material hardened in place. The tube and contained circuitous passage may first be coiled in one direction, and then be coiled in the opposite direction, in a relation preventing twisting of the line as the device moves downwardly therealong.
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