Abstract: A double pulley device comprises a pair of sheaves arranged in line inside a reverse U-shaped metal support flange-plate, each sheave being mounted rotating free on a fixed spindle of the flange-plate. At least one orifice for the passage of a snap-hook, is situated between the two spindles of the sheaves, so that the fixing point of the snap-hook is positioned above the point of contact of the sheaves with the cable. One of the wings of the flange-plate is arranged to enable the mobile finger of the snap-hook to be opened when the double pulley device is fitted onto the cable.