Clutch mechanism for use in safety apparatus

Fall-arrest safety apparatus which is attachable to a fixture and incorporates a safety line drum (1) for holding a safety line (3) and permitting it to be drawn from the drum (1) in response to pulling force on the line exerted by a person attached to that line;

• the apparatus having means which functions automatically initiated by activation of a speed sensitive clutch device to decelerate the drum if its unwinding speed becomes excessive as it does in the event of the worker falling;
• characterised in that the speed-sensitive clutch device for initiating deceleration of the safety line drum incorporates (a) at least one drive-transmitting coupling element (17) which is connected to the safety line drum (1) so that it bodily rotates with the drum (1) about its axis of rotation and is displaceable from an inactive position (FIG. 1) into a drive-transmitting position (FIG. 2) in which it transmits drive and (b) an inertia member (20) which is freely rotatable about said axis and relative to the drum itself;
• and in that said inertia member (20) is formed and disposed so that on rapid acceleration of the drum (1) in consequence of a fall it exerts pressure, due to its inertia, against said coupling element (17) thereby to cause or assist movement thereof into its drive-transmitting position.