A four-rope grab is a loading and unloading tool for transporting and carrying large items such as ebony and stones. It is mainly used in conjunction with a bridge or gantry crane with two sets of lifting drums to grab various types of loose accumulations and perform operations such as loading, unloading, and transferring materials.
The working principle of the four-rope grab is as follows:
1. The material-taking action of the grab is controlled by the lifting drum and the opening and closing drum on the crane. The ends of the two steel wire ropes wound on the lifting drum are fixed on the wedge shell of the grab head, and the wedge shell is hinged to the grab head. When the lifting drum rotates, the steel wire rope drives the grab up and down through the wedge shell.
2. The two steel wire ropes wound on the opening and closing drum are wound between the pulleys of the grab head and the crossbeam through the guide wheel to control the opening and closing of the grab.
3. When taking materials, the grab is lowered to the material pile in an open state, and the opening and closing drum does not move at this time. Then, the opening and closing drum is started in the lifting direction (the lifting rope does not move), and the jaw plate of the grab digs into the material under the action of the grab's own weight. When the grab is completely closed, the lifting drum and the opening and closing drum are started at the same time to lift the fully loaded grab to a certain height.
4. Next, start the crane to move the grab to the unloading position, start the opening and closing drum in the descending direction (the lifting drum does not move), and the grab opens to unload.
In addition, there is a clamping mechanism inside the four-rope grab, which retracts the two sets of clamping claws inward through hydraulic or mechanical force to clamp the objects. When the objects need to be put down, the claws of the clamping mechanism will relax and release the objects by releasing the hydraulic or mechanical force.
Before using the four-rope grab, the fixing block on the grab should be removed first so that the grab can be opened and closed freely. At the same time, check whether the lubrication of the grab is good, and whether the various connection parts are loose. If there is any looseness, tighten it in time. The wire rope should also be adjusted so that the grab is in a free balance state.
Please note that when using a four-rope grab, be sure to follow operating procedures and safety requirements to ensure the safety of personnel and equipment.
