Service condition: when the bridge-type grab ship-unloader is handling coal, ore and other bulk using the grab, in order to quickly replace all kinds of grabs, the steel wire rope pear-shaped sling will be mounted on end of unloading steel wire rope, grab on-off and holding steel wire rope, and the C-shaped quick shackle will be connected between pear-shaped sling so that in the closed state of the grab, part of the rope will be drawn out to pass the connection mechanism to smoothly bypass the opening and closing pulley, thus the grab bucket can be lifted to an ideal height.