Abstract: An emergency stop mechanism for a lifting device capable of moving a load along a predetermined path against and with the force of gravity using a winch-operated primary cable, and wherein the primary cable accomplishes a lifting function by pulling the load in the direction of increased potential energy. The emergency stop mechanism comprises a secondary cable suspended stationary and parallel to the path of movement of the load. A braking device fastened to the load is actuated by a decrease in tension in the primary cable below a predetermined minimum amount of tension and responds to such decrease by gripping the secondary cable.