Bar intended to be clamped removably on the roof of a motor vehicle

The load-carrying bar, normally used in conjunction with at least one other, consists of a central and/or main section (8), a locking member (15) and a regulator (27) with two threaded components (28, 29). One of the threaded components (29) is connected to an actuator (33) via a torque limiter (39) which prevents excessive force being applied to the regulator when it is being rotated in the direction required to fasten the bar while allowing greater force to be applied to undo it.