A quick descent device (1; 1'; 1"; 1′′′) for a pantograph , this pantograph comprising a frame , a bow intended to be placed against a catenary , a hinged arm connecting the bow to the frame, means for deploying the hinged arm communicated with supply means , belonging to a rail vehicle equipped with this pantograph, these supply means being capable of supplying a compressed fluid, in particular compressed air, this quick descent device comprising: - a valve including two chambers , which are separated by a membrane , the first chamber called pilot chamber comprising an orifice for driving the valve, the second chamber called main chamber comprising an inlet orifice and an outlet orifice , said outlet orifice allowing the discharge of the fluid to the atmosphere, this membrane having a first functional position called closed functional position in which it seals the outlet orifice, as well as a second functional position called open functional position in which it does not seal the outlet orifice, - at least one contact strip capable of being fastened on the body of the bow, this contact strip being intended to come into contact with the catenary and being equipped with a degradation detection circuit configured to be supplied by said fluid, - at least one supply line intended to supply fluid to the main chamber via the inlet orifice thereof, each supply line being configured to be communicated, by the fluid, with the supply means, - at least one supply line intended to supply fluid to the pilot chamber, each supply line being configured to be communicated, by the fluid, with the supply means, - at least one monitoring line extending from the pilot chamber of the valve, to supply a respective circuit for detecting degradation of the contact strips , - connecting means , configured to connect, by the fluid, the deployment means and the main chamber , so that at least one substantial portion of the compressed fluid is discharged from the deployment means, when the membrane is in the second functional position called open functional position, this quick descent device further comprising means for temporarily blocking the supply of fluid to the main chamber. - a valve including two chambers , which are separated by a membrane , the first chamber called pilot chamber comprising an orifice for driving the valve, the second chamber called main chamber comprising an inlet orifice and an outlet orifice , said outlet orifice allowing the discharge of the fluid to the atmosphere, this membrane having a first functional position called closed functional position in which it seals the outlet orifice, as well as a second functional position called open functional position in which it does not seal the outlet orifice, - at least one contact strip capable of being fastened on the body of the bow, this contact strip being intended to come into contact with the catenary and being equipped with a degradation detection circuit configured to be supplied by said fluid, - at least one supply line intended to supply fluid to the main chamber via the inlet orifice thereof, each supply line being configured to be communicated, by the fluid, with the supply means, - at least one supply line intended to supply fluid to the pilot chamber, each supply line being configured to be communicated, by the fluid, with the supply means, - at least one monitoring line extending from the pilot chamber of the valve, to supply a respective circuit for detecting degradation of the contact strips , - connecting means , configured to connect, by the fluid, the deployment means and the main chamber , so that at least one substantial portion of the compressed fluid is discharged from the deployment means, when the membrane is in the second functional position called open functional position, <EOS>