Lift arm brief

Boom commonly known as boom, boom. A metal structure supporting the bidirectional bending of a hoisting rope, fetching device or luffing car. By connecting pin, wire rope or hydraulic cylinder support in the crane turntable or tower body. For the pitching swing of the boom, the Angle of the Angle is changed by the luffing mechanism to change the amplitude and lifting height of the crane; The horizontal boom is varied by moving a luffing cart back and forth over it. According to different structures, it can be divided into truss jib and box jib; According to different functions, it is divided into lifting boom, main lifting boom, deputy lifting boom, telescopic boom, folding arm, goose head, etc.

Truss lifting boom

Truss lifting arm is a lifting arm welded into lattice structure by section steel and pipe. Usually consists of a number of segments connected by bolts or pins to the desired length. According to the truss section shape has square, rectangle and triangle three kinds. It is characterized by light weight, which is conducive to improving the lifting performance of the crane; However, the assembly and disassembly time is long, and the manufacturing process is poor.

Truss jib crane: a crane with a truss structure. There are more varieties, truss arm truck crane, truss arm tire crane, truss arm crawler crane and tower crane. The light dead weight of the truss boom is beneficial to improve the lifting performance of the crane, especially under the condition of large scale. Due to the piecewise assembly, the auxiliary time before operation is long, but the work is reliable. In the crane has a larger proportion.

Box derrick

Box jib is made of plate welding, and the cross section is hollow closed jib. Usually slightly heavier than the same weight truss boom, but good technology, easy to make telescopic boom. There are inverted trapezoidal lifting boom and so on. Widely used in truck crane and tire crane. To reduce the weight, holes can be made in the wall of the case, or welded with reinforced sheet.

Inverted trapezoidal derrick

Inverted trapezoidal derrick cross section profile is inverted trapezoidal box boom. It is an improved type of ordinary rectangular boom. The upper cover plate is wide, and the web on both sides deviates from the symmetrical center line and inclines inward. Usually there are reinforcement strips as long as the boom joint welded between the lower flange and the lower web along the length direction. The lower cover plate under compressive stress is narrow, which is conducive to local buckling stability of the lower cover plate. The reinforcement of the web compressive stress area improves its buckling ability, so the web can be increased or reduced, the bending resistance of the section is improved, and there is a large available space inside the boom. Therefore, it is suitable for large telescopic boom with large lifting weight and multiple telescopic boom joints.

Single lifting point lifting boom

Only one section of a single point crane tower crane has a boom connected with the boom cable. In the section, a general connection with the boom cable, but sometimes can also be provided with two; The root of the boom is hinged with the tower body, the lifting point is located in the arm, and the whole boom is an overhanging beam; During the design calculation, the mechanical model in the lifting plane is statically determinate structure, so it is convenient to set up, install and adjust; The long arm is heavier than the double lifting point lifting arm and the multi lifting point lifting arm.

Double lifting point lifting boom

A tower crane has two sections with a boom connected to a boom cable. In the design calculation, the mechanical model in the lifting plane is the three-fulcrum overhanging beam, which is a statically indeterminate structure, so it is a little troublesome to erect, install and adjust. However, in the long lifting boom, due to the good stress, it can reduce the dead weight, which is widely used.

Hoist the heavy arm more

In the design and calculation of multi-point lifting boom, the mechanical model of lifting plane is multi-fulcrum overhanging beam, so it is the multi-statically indeterminate structure of the lifting boom. Characteristics similar to double lifting point boom, but not commonly used.