The component parts of the device shown in the figure, were a spindle a which carried a righthand thread of a steep pitch marked b, and a portion c with a fine left-hand thread. Both portions of the screw fitted into and carried each half of the gripping portion I and k. The spindle a was secured to the carrier frame n; lever h was keyed to the spindle and carried a balance weight i. If this lever h was moved to the left the jaws opened, whilst, if it was turned to the right, it closed in such a way that first the jaw k with the quick thread closed upon the rope, and with any further movement of the lever the slow pitch screw closed the other jaw. The whole of this could be performed by a movement of not more than 90° of the coupling lever.