| 摘要 |
A descender 10 having a resistance feed arrangement 14, 15 for a rope 5, a self-acting brake (12, 14, 15, 18) to automatically apply a braking force to the rope 5 in certain circumstances such as an emergency when the user is knocked unconscious, and a variable braking mechanism 21 which allows the user to selectively vary the braking force by moving a braking surface 24 in a direction away from the rope 5 to allow a controlled reduction of the braking force, and which will automatically return to a position for maximum braking force when released. Preferably, the variable braking mechanism 21 is in the form of a cam 22 selectively pivotal by means of a handle or lever 23 which may be connected to the tail end of the rope 5 by a retention arrangement 25 to allow easy actuation of the mechanism 21. In another embodiment, the descender 10 is provided with a sheave 48 as part of the resistance feed through the descender, and which is selectively freely rotatable for larger diameter ropes 5 and which may be rotatably locked for smaller diameter ropes. In this way, the resistance of the feed of the rope 5 through the descender 10 can be adjusted to suit different diameter ropes.
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