Heavy duty gantry crane is a type of bridge crane, with single girder and double girder types. The main girder is supported by two brackets. It is mostly used for outdoor operations and moves on wheels, rails or rail systems. Workshops, warehouses, freight yards, railways and shipyards use gantry cranes as a variant of overhead cranes as a lifting solution. It is mainly used for bulk cargo loading and unloading in open cargo yards, storage yards, and bulk cargo. The outdoor gantry crane has the characteristics of high site utilization rate, wide operation range, wide adaptability and strong versatility.
Main beam form
1. Single girder
The single main girder gantry crane has a simple structure, is easy to manufacture and install, and has a small mass. Most of the main girder is a partial rail box frame structure. Compared with the double girder gantry crane, the overall rigidity is weaker. Therefore, this form can be used when the lifting weight Q≤50t and the span S≤35m. There are two types of L-shaped and C-shaped gantry legs for single girder gantry cranes. The L-type is easy to manufacture and install, has a good stress condition, and its own mass is small, but the space for hoisting goods through the outriggers is relatively small. The C-shaped leg is made into an inclined or curved shape, and the purpose is to have a larger lateral space so that the goods can pass through the leg smoothly.
2. Double main girder
The double main girder gantry crane has strong bearing capacity, large span, good overall stability, and many varieties, but its own quality is larger than that of the single main girder gantry crane with the same lifting capacity, and the cost is also higher. According to the structure of the main girder, it can be divided into two forms: box girder and truss. Generally, a box-shaped structure is used.
main beam structure
1. Truss beam
The structural form welded by angle steel or I-beam has the advantages of low cost, light weight and good wind resistance. However, due to the many welding points and the defects of the truss itself, the truss beam also has the disadvantages of large deflection, low stiffness, relatively low reliability, and frequent inspection of welding points. It is suitable for sites with lower safety requirements and lower lifting capacity.
2. Box girder
The steel plate is welded into a box structure, which has the characteristics of high safety and high rigidity. It is generally used for large-tonnage and super-large-tonnage gantry cranes. As shown in the picture on the right, MGhz1200 is the largest gantry crane in China with a lifting capacity of 1,200 tons. The main girder adopts a box girder structure. The box girder also has the disadvantages of high cost, heavy weight, and poor wind resistance.
3. Honeycomb beam
Generally refers to “isosceles triangular honeycomb beam”, the end face of the main beam is triangular, there are honeycomb holes on the oblique belly on both sides, and there are chords on the upper and lower parts. Honeycomb girder absorbs the characteristics of truss girder and box girder, and has greater rigidity, smaller deflection and higher reliability than truss girder. However, due to the welding of steel plates, the self-weight and cost are slightly higher than those of truss beams. It is suitable for sites or beam yards that are frequently used or have heavy lifting capacity. Since this beam type is a patented product, there are fewer manufacturers.
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