| 摘要 |
The system has a photo-detector (1) which sends pulses, representing distance, to a pre-selection counter (4) which controls a whole number of constant pulses defining the spacing for the whole of the length relation between the cable loop and the number of vehicles. The pre-selection counter (4) possesses stages (P1,P2) associated with two contacts (5,6). The stage (P1) is pre-selected to be the least stopping distance spacing value measured beforehand and its contact (5) actuates the stop control for the installation. The second stage (P2) is pre-selected to be the spacing value and actuates automatic zero reset of the counter, without loss of pulses, and operation of the contact (6). The length measurement is made by the pulses counted by the photo-detector (1) on an adhesive strip (2), having alternate black and white bands, which is stuck on the edge of the disk (3) of the winch driving the cable loop.
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