| 摘要 |
PROBLEM TO BE SOLVED: To surely detect serious damage without detection of light damage through detection of damage on the pantagraph by providing an optical fiber at the upper part of the pantagraph, propagating optical beam to an optical fiber and then detecting intermission of propagation of optical beam. SOLUTION: If a slide plate 4 is damaged up to a through hole 6, a trolley line is in contact with an optical fiber 5, thereby breaking this optical fiber 5. Here, the optical fiber 5 is located at the area higher than the upper surface of a boat body 3. Therefore, the optical fiber 5 is surely cut before the trolley line is in contact with the boat body 3. When the optical fiber 6 is broken, an optical signal is not returned to an internal switch and therefore an alarm buzzer sounds. Accordingly, a maintenance person within a vehicle can detect that the slide plate 4 is broken up to the through hole. A light damage not impeding operation of the pantagraph is neglected and since the damage can be detected before it becomes a serious damage in which the trolley line is in contact with the boat body 3, damage of the trolley line can be prevented.
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