| 摘要 |
A roping device having an automatic emergency brake includes a generally elongate body having an attachment means at one end, a first rotatable sheave mounted on the body having an annular groove defining a generally semi-circular guide path for a rope, and a braking mechanism mounted to the body generally adjacent the first sheave for selectively braking the rope which, in use, passes therethrough. The braking mechanism is biased towards an engaged position in which the rope is prevented from moving in a first direction through the device. An emergency release mechanism holds the braking mechanism away from its engaged position during normal operation of the device so that the rope is allowed to move through the device in the first direction. The release mechanism includes a centrifugal trigger means associated with the sheave, a plate member rotatably mounted on the body adjacent the sheave, about the same axis as the sheave and being positionable in an engaged position holding the braking mechanism away from its engaged position, and a disengaged position in which the braking mechanism is released into its engaged position. The centrifugal trigger means includes a lobe which projects laterally from the plate member at a predetermined radius from the rotational axis, and a member which is mounted on the sheave and is movable against a bias force from a retraced position wherein it does not obstruct movement of the plate member and the lobe about the rotational axis, to an extended position by centrifugal force when in use the speed of rotation of the sheave exceeds a predetermined triggering speed. In the extended position the member engages the lobe to cause the plate member to rotate with the sheave into its disengaged position, which triggers the release of the braking mechanism.
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