Working principle of grab crane

Grab cranes refer to cranes that use grabs as lifting spreaders, including single-beam grab cranes, double-beam grab cranes , single-beam grab gantry cranes, and double-beam grab gantry cranes. Some friends don’t know much about the working principle of grab cranes. I will briefly introduce you here.

There are mechanical and hydraulic grab types.

Let's first talk about the working principle of mechanical grabs .

The grabbing device of the grab crane is a grab that can grab bulk materials. The grab crane has an opening and closing mechanism and a lifting mechanism. The grab is suspended on the opening and closing mechanism and the lifting mechanism with four steel wire ropes. The opening and closing mechanism drives the grab bucket to close and grabs the material. When the bucket mouth is closed, the lifting mechanism is immediately activated, so that the four steel wire ropes are evenly loaded for lifting work. When unloading, only the opening and closing mechanism is activated, and the hopper opens immediately, tilting the material. Except for the different lifting mechanism of the grab crane, the rest of the structure is basically the same as that of the hook crane.

The working principle of a hydraulic grab is similar to that of a mechanical grab, except that the power mode of the grab opening and closing is different.

For the use rules and maintenance of grab cranes, in addition to the general hook crane use rules, there are the following precautions:

(1) Before each shift, check the opening and closing mechanism of the grab bucket, the tightness of the jaw plate closure, and check the fixation of the jaw plate, the hinged connection of the support rod and the lubrication status of each grab bucket.

(2) Check the condition of the guide wheel of the grab opening and closing rope and the fastening and connection of the grab suspension rigging.

(3) Test run with empty car, check the correctness and reliability of the work of the grab closure mechanism.

(4) Grab buckets are not allowed to grab the whole piece of objects, and grab buckets are not allowed to lift and unload feeding equipment and railway vehicles.

(5) The height from the hopper when the grab is unloaded shall not be greater than 200mm.

(6) When lifting the grab, the speed of the closing rope and the hoisting rope are equal, and the force of the wire rope is even.

(7) The upper limit position of the grab when lifting is that the top of the grab is ≥1m from the upper limit switch, and when it is lowered, the distance between the bottom of the grab and the box is ≥0.1m.

Grab cranes are used in the lifting of bulk materials, coal plants, garbage plants and other occasions. Reasonable use of grab cranes can greatly improve work efficiency.

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