Composition and structure of hoisting machinery

The working mechanism includes: lifting mechanism, operating mechanism, luffing mechanism and rotating mechanism, which are called the four major mechanisms of the crane.

(1) The lifting mechanism is a mechanism used to realize the vertical lifting of materials. It is an indispensable part of any crane and is therefore the most important and basic mechanism of the crane.

(2) The operating mechanism is a mechanism that realizes the horizontal transportation of materials through the operation of the crane or the lifting trolley. It can be divided into trackless operation and track operation. According to its driving mode, it can be divided into self-propelled and traction type.

(3) The luffing mechanism is a working mechanism unique to the boom crane. The luffing mechanism changes the operating range by changing the length and elevation angle of the boom.

(4) The rotating mechanism makes the boom rotate around the vertical axis of the crane to move materials in the annular space. The crane achieves the purpose of transporting materials through the single movement of a certain mechanism or the combined movement of multiple mechanisms.

The drive device is a power device used to drive the working mechanism. Common drive devices include electric drive, internal combustion engine drive and human drive. Electric energy is a clean and economical energy source. Electric drive is the main drive type of modern cranes. Almost all rail cranes, lifts, elevators, etc. that operate within a limited range are driven by electricity. For mobile cranes that can move over long distances (such as mobile tire cranes), internal combustion engines are mostly used. Human drive is suitable for some light and small lifting equipment, and is also used as auxiliary, backup drive and temporary power for accidents (or accident states) of some equipment.

The picking device is a device that connects materials with cranes for material lifting by lifting, grabbing, sucking, clamping, supporting or other means. Different types of picking devices are used according to the different types, shapes and volumes of the materials to be lifted. For example, hooks and rings are often used for finished items; grabs and hoppers are often used for bulk materials (such as grain, ore, etc.); and cylinders and tanks are used for liquid materials. There are also special lifting equipment for special materials, such as lifting beams for lifting long materials, lifting electromagnetic chucks for lifting magnetic materials, rotating hooks specially used in metallurgy and other departments, and retrieval devices such as spiral unloading and bucket wheel unloading, as well as special lifting equipment for containers. Suitable retrieval devices can reduce the labor intensity of operators and greatly improve work efficiency. Preventing the falling of the hoisted objects and ensuring the safety of the operators and the objects from being damaged are the basic requirements for the safety of the retrieval device.

Metal structure is a steel structure that uses rolled steel (such as angle steel, channel steel, I-beam, steel pipe, etc.) and steel plate as basic components, connected by welding, riveting, bolting and other methods according to certain composition rules, and bears the deadweight and load of the crane. The weight of the metal structure accounts for about 40% to 70% of the weight of the whole machine, and heavy cranes can reach 90%; its cost accounts for more than 30% of the cost of the whole machine. According to its structure, the metal structure can be divided into two types: solid belly type (made of steel plate, also known as box-type structure) and lattice type (generally made of steel, common root frame and lattice column), which are the basic load-bearing components of the crane metal structure. These basic load-bearing components include columns (axial load-bearing components), beams (bending components) and booms (compression-bending components). Different combinations of various components form cranes with different functions. Complex force, heavy weight, many consumables and overall mobility are the working characteristics of the crane metal structure.

Various lifting operations are carried out by controlling the movement of various mechanisms and the whole machine through electrical and hydraulic systems. The control and manipulation system includes various manipulators, displays and related components and circuits, and is the interface for human-machine dialogue. The requirements of safety ergonomics are concentrated here. The status of this system is directly related to the quality, efficiency and safety of the lifting operation.

The significant difference between cranes and other general machines is the large, movable metal structure and the combined operation of multiple mechanisms. The intermittent cycle operation, the unevenness of the lifting load, the inconsistency of the movement cycle of each mechanism, the unequal timing of the mechanism load, and the coordinated operation of multiple people have increased the complexity of crane operations, the many safety hazards, and the wide range of dangers. There are many accident-prone points and serious consequences of accidents, so the safety of cranes is particularly important.