Abstract: A pressure drop indicator for a braking system comprising two independent circuits, one of said circuits comprising a pressure limiter, said indicator comprising a body formed with a bore, a movable member slidably mounted in said bore and responsive to the pressure in both circuits, said movable member being adapted to co-act with a control element of an electric switch so as to close an electric signal circuit in case of fluid leakage in one of said circuits, said movable member comprising a first piston provided with a rod movable in a bore formed in the other or second piston, said second piston being adapted to co-act with said electric switch control element between two axial abutment positions, said piston providing at the ends of said bore in said body first and second chambers to which the feed lines of said first and second circuits are adapted to be connected, said second circuit comprising said pressure limiter, the pressure drop indicator being characterized in that the end of the rod of said fir