An arrangement for secure transfer of a travelling trolley between a first and a second rail (3', 3") in a hoisting system, the arrangement including: - a first stop which in an open position is arranged to allow passage of the trolley from the first rail to the second rail when the rails are aligned, and which in a closed position is arranged to form a barrier in the path of the trolley, preventing passage of the trolley past the free end of the first rail when the rails are not aligned; - a second stop (7") which in an open position is arranged to allow passage of the trolley from the second rail to the first rail when the rails are aligned, and which in a closed position is arranged to form a barrier in the path of the trolley, preventing passage of the trolley past the free end of the second rail when the rails are not aligned; - a first and a second engagement means (11', 13') arranged to engage when the rails are aligned; - a third and a fourth engagement means (11", 13") arranged to engage when the rails are aligned; - the first stop arranged so as to pivot in relation to the first rail, and such that the first stop is coupled with the first engagement means so that the first stop pivots out of the path of the trolley when the first and second engagement means engage; - the second stop arranged so as to pivot in relation to the second rail, and such that the second stop is coupled with the third engagement means so that the second stop pivots out of the path of the trolley when the third and fourth engagement means engage; characterised in that the first and third engagement means (11', 13') each includes a projecting part (15', 15"), and that the second and fourth engagement means (11", 13") each include a track (17', 17") adapted to receive respective projecting parts, wherein both tracks are curving such that respective projecting parts are displaced in relation to the longitudinal direction of the rails by insertion into the respective tracks. - a first stop which in an open position is arranged to allow passage of the trolley from the first rail to the second rail when the rails are aligned, and which in a closed position is arranged to form a barrier in the path of the trolley, preventing passage of the trolley past the free end of the first rail when the rails are not aligned; - a second stop (7") which in an open position is arranged to allow passage of the trolley from the second rail to the first rail when the rails are aligned, and which in a closed position is arranged to form a barrier in the path of the trolley, preventing passage of the trolley past the free end of the second rail when the rails are not aligned; - a first and a second engagement means (11', 13') arranged to engage when the rails are aligned; - a third and a fourth engagement means (11", 13") arranged to engage when the rails are aligned; - the first stop arranged so as to pivot in relation to the first rail, and such that the first stop is coupled with the first engagement means so that the first stop pivots out of the path of the trolley when the first and second engagement means engage; - the second stop arranged so as to pivot in relation to the second rail, and such that the second stop is coupled with the third engagement means so that the second stop pivots out of the path of the trolley when the third and fourth engagement means engage; characterised in that the first and third engagement means (11', 13') each includes a projecting part (15', 15"), and that the second and fourth engagement means (11", 13") each include a track (17', 17") adapted to receive respective projecting parts, wherein both tracks are curving such that respective projecting parts are displaced in relation to the longitudinal direction of the rails by insertion into the respective tracks.