This rapid lowering device (1) comprises a valve (20) comprising two chambers (22, 24), at least one friction strip (10, 12) fixed on the body of the pantograph bow, intended to come into contact with the catenary and equipped with a degradation detection circuit (11,13), at least one supply line (44) of fluid to the main chamber of the valve, at least one supply line (30, 32) intended to supply this fluid to the pilot chamber of the valve, as well as to at least one monitoring pipe (14) extending from the pilot chamber (22) of the valve, to supply a respective detection circuit (10 , 12). According to the invention, this rapid descent device comprises means (40) for temporarily blocking the supply of fluid to the main chamber, which reliably ensures the initial rise of the pantograph until it comes into contact with the catenary. . Figure for the abstract: Fig. 2.
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