What Is a Grab Bucket?

Grab bucket is a special tool for cranes to catch dry and bulk cargo. Two or more bucket-shaped jaw plates that can be opened and closed are combined to form a container space. When loading, the jaw plate is closed in the material pile, the material is caught into the material space, and the jaw plate is in the material pile when unloading. It is opened in the upper suspended state, and the materials are scattered on the pile. The opening and closing of the jaw plate is generally controlled by the wire rope of the crane lifting mechanism. Grab bucket operation has no heavy manual labor, can achieve high loading and unloading efficiency and ensure safety, and is the main dry bulk cargo loading and unloading tool at the port. According to the type of operation cargo, it can be divided into ore grabs, coal grabs, grain grabs, and wood grabs. ^[1]

[zhu dòu]

Grab bucket is a special tool for cranes to catch dry and bulk cargo. Two or more bucket-shaped jaw plates that can be opened and closed are combined to form a container space. When loading, the jaw plate is closed in the material pile, the material is caught into the material space, and the jaw plate is in the material pile when unloading. It is opened in the upper suspended state, and the materials are scattered on the pile. The opening and closing of the jaw plate is generally controlled by the wire rope of the crane lifting mechanism. Grab bucket operation has no heavy manual labor, can achieve high loading and unloading efficiency and ensure safety, and is the main dry bulk cargo loading and unloading tool at the port. According to the type of operation cargo, it can be divided into ore grabs, coal grabs, grain grabs, and wood grabs. ^[1]

Grab by two left or right combo buckets or multiple

Classification by shape

According to the shape, it can be divided into shell-shaped grab and orange petal grab. The former consists of two complete

Shell grab : suitable for loading various bulk cargoes, minerals, coal, gravel, earthwork, etc. in ports, docks, station yards, mines, etc. It can also be used for earthwork excavation, foundation and trench excavation, highway construction, railroad tracks Laying and other works.

First select the grapple power form according to the crane. According to the definition of a grab bucket: a grab bucket is a pick-up device under the crane, so even the most advanced grab buckets can not complete the work independently without the crane. Conversely, no matter how advanced and large-tonnage ship unloaders are, it is inseparable from grabs and efficient. Therefore, what kind of crane should be equipped with what kind of grab bucket, the wrong configuration can not be used, with a large overload can not be used. For example: The crane hoisting drum is single, and it must be equipped with a mechanical grab. It can only be equipped with a single-cable grab. If a four-cable grab is equipped, the grab will not work; for another example: the rated lifting capacity of the crane is 25t, to be equipped with a grapple, can only be equipped with the grapple's own weight + grasped cargo weight = <25t, with a large crane overload, unsafe.

Secondly, select the structure of the grab bucket according to the type of loading and unloading. According to the definition of grab: grab is used to load and unload various kinds of cargo. Therefore, what kind of cargo is loaded and unloaded, it should be equipped with the corresponding grab. Mismatches are either inefficient or unusable. For example, if the type of cargo to be loaded and unloaded is coal, a light double-lobed grab is equipped. If a heavy double-lobed mine grab is used, the loading and unloading efficiency is at least 50% lower. Another example: the type of cargo that needs to be loaded and unloaded is coal, which is equipped with a double-flap grab. If it is equipped with a toothed wood grab, it is a Chinese saying that bamboo baskets fetch water and are empty. can not be used.

The common failure in the use of the grapple is abrasive wear. According to the analysis of relevant data, it can be found that in the failure form of the grapple, about 40% of the work performance is lost due to pin wear, and the work performance is lost due to wear of the bucket blade. About 30%, and about 30% loss of working performance due to pulley wear and other component damage. It can be seen that improving the abrasion resistance of the grab pin and the sleeve and the abrasion resistance of the blade edge of the bucket are important ways to improve the life of the grab. There are external factors and internal factors that affect material wear. External factors include factors such as load, sliding speed, abrasive hardness and geometry. Internal factors include the chemical composition of the material, the type of carbide, and the microstructure. The external factors are self-evident and are not described here one by one. In order to improve the service life of the grab bucket, it is necessary to select different wear-resistant materials for different conditions of the wear parts of the grab bucket, and supplement them with different processing techniques, thereby greatly improving the service life of the grab bucket.
Due to the frequent use of grabs, and the limited operation level of the driver of the ship unloader, the failure rate of grabs is very high. Therefore, it is necessary to strengthen the inspection of these parts in the daily inspection process, and also to maintain these parts , As short as possible the life of the grab, improve productivity. In order to better manage the grabs, ensure production, and ensure safety, the following provisions are formulated based on the composition of the personnel involved in the use, maintenance, and repair of the grabs, the scope of work, and the work procedures:
a. The watchkeeper should arrange the refueling of the grapple in a timely manner every day; every Monday and Thursday, arrange the refueling of the bearing beam on the grapple; if there are special circumstances, a maximum of one day can be postponed, and the situation should be recorded in the watch log, and the second day will be the watchkeeper Make arrangements separately.
b. The driver should meet the standard for fuel replenishment and ensure adequate lubrication; if the fuel is not refilled, it should be recorded in time and reported to the inspector or the competent technician. It is required to make a record of each refueling situation in the operation log.
c. The driver should take the initiative to accept the opinion of the grapple fueling inspector when refueling.
d. When the driver is operating, avoid accidents such as rubbing the bucket against the cabin, and prevent similar incidents caused by incorrect operation methods.
e. The driver should observe the use of the grab in real time during the operation. If the wear of the chain or the quick joint is found, he should refuel in time. If he finds other failures or suspected failures of the grab, he should stop the inspection and report in a timely manner while running. Make a record in the log.
f. Inspection personnel should be timely, accurate and effective in the inspection of grabs, so as to strengthen the plan for replacement and repair of grabs.
g. Grab failures or suspected failures detected by inspection shall be reported to the grab supervisor in a timely manner and recorded on the inspection and repair form.
h. After the inspector replaces the grab on the machine, he should record and sign all the problems in the grab in the grab management account and give it to the grab supervisor in time.
i. In addition to explaining the situation of the on-board grab to the technicians during the holidays, technicians should also record the matters needing attention on the duty records. Duty personnel shall record the specific situation and handling process on the duty record for any failures that occur during the duty period.
j. For each grab overhaul, the grab team must do a good job of statistical work (including repair items, repair time, difficulties encountered in repair, summary of repair materials, etc.), special statisticians, and record in grab management In the ledger.
k. The grapple management account goes with the grapple, and it is recorded in real time during use and repair; after the grapple is repaired, the grapple supervisor accepts and signs it.
l. Grab supervisors should make statistics on the status of spare grabs and update the replacement of important parts of the grabs in a timely manner; if repairs require on-board processing, they should inform the competent technicians in advance.
m. The grab repairman should always keep in touch with the grab supervisor when repairing the dock, and should notify the grab supervisor in advance when coordination with the dock equipment is involved.
n. During the grab repair, if the parts need to be replaced, the principle of interchangeability should be followed; if the replacement process involves the assembly of other parts of the grab (including the repair of the docker's class), try to avoid destroying them The original way of assembly.
o. During the repair process, the person in charge of repair shall urge the repair person to pay attention to safety, and the repair person shall obey the order of the person in charge of repair. Focus on repair quality and prevent rework. In case of repairs on the dock, bills and consumption bills should be issued in time. ^[3]