| 摘要 |
The apparatus is a fall arrestor and lockdown device for vertical lift doors, particularly single membrane fabric vertical lift doors. A pulley on a sensing arm engages the cable which raises and lowers the door. Alternatively, the sensing arm is directly attached to a belt. The sensing arm is mechanically linked to a spring loaded pin reciprocating within a tubular housing. When the cable or belt is tensioned, the sensing arm rotates upwardly to a position where the pin is retracted and the spring compressed thereby allowing the door to move vertically. However, when the cable or belt is not tensioned, the spring urges the pin to an extended position to engage regularly spaced apertures within the guide channel. When the cable or belt is not tensioned due to a cable or belt failure, the device operates as a fall arrestor. When the cable or belt is not tensioned because the door is fully lowered to the ground, the device acts as a lockdown device.
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