What is the structure of a crawler crane? What are the features?

A crawler crane is composed of components such as a traveling mechanism, a slewing mechanism, a chassis, and a boom. The walking mechanism features a chain track to reduce pressure on the ground. The rotating mechanism is a turntable mounted on the chassis, which allows the fuselage to rotate 360 degrees. Inside the fuselage are the power unit, winch, and control system. The boom is a lattice-shaped member made of angle steel, with its lower end hinged to the front of the chassis and rotating along with it. The boom can be extended in sections, and it is equipped with two sets of pulley blocks (a lifting pulley block and a luffing pulley block); the steel cable connects to the winch inside the machine body via the top of the boom. If the working device at the end of the boom is changed, it will become a single-bucket excavator. Crawler cranes are characterized by their flexible operation, as they can rotate 360 degrees on their own. It can operate on flat and solid ground. Thanks to the tracks, it can operate on soft, muddy ground and travel on uneven surfaces. Currently, crawler cranes are widely used in the construction of prefabricated structures, especially in the installation of single-story industrial plant structures. The disadvantages of crawler cranes are poor stability; they should not be used for lifting heavy loads, they have a slow traveling speed, and their tracks can damage road surfaces. Therefore, they are usually transported using flatbed trailers when being moved from one location to another.

Introduction to Crawler Crane: A boom-mounted crane that moves using tracks. 　　A crawler crane is a self-propelled crane used in the construction of high-rise buildings. 　　It has a large track contact area, good traction, and strong adaptability; it can move while carrying loads, making it suitable for lifting operations at construction sites. It can perform various tasks such as digging, ramming soil, and driving piles. However, due to the slow walking speed, other vehicles are needed to transport it to the construction site. Composition A crawler crane is composed of a power unit, a working mechanism, as well as a boom, a turntable, a chassis, etc. 　　①The boom is a multi-segment truss structure; by adjusting the number of segments, its length can be changed. Its lower end is hinged to the front part of the turntable, while its upper end is supported by a pulley block connected to a luffing wire rope, allowing the tilt angle of the boom to be adjusted. 　　There are also those with an auxiliary arm attached to the top of the boom, with the auxiliary arm forming a certain angle with the boom. The lifting mechanism consists of a primary and a secondary winch system; the primary winch system is used for lifting loads with the boom, while the secondary winch system is used for lifting loads with the auxiliary arm. 　　②Turntable: Mounted on the chassis via swing bearings, it allows all the weight of the turntable to be transferred to the chassis. It is equipped with a power unit, transmission system, winch, control mechanism, counterweights, and a canopy. The power unit enables the turntable to rotate 360° through a rotating mechanism. The swivel bearing consists of upper and lower rollers, along with rolling elements (balls or rollers) between them; it enables the transfer of all the weight on the turntable to the chassis, while ensuring the free rotation of the turntable. 　　③Chassis Includes the traveling mechanism and traveling devices: the former enables the crane to move forward and backward as well as turn left and right ； The latter consists of a track frame, drive wheels, idler wheels, support wheels, sprockets, and track rollers, among other components. The power unit rotates the drive wheels through a vertical shaft, a horizontal shaft, and chain transmission, thereby driving the idler wheels and support wheels and enabling the entire machine to move forward by rolling on its tracks. Main technical parameters: There is a lifting capacity or lifting torque. The selection depends mainly on the lifting capacity, working radius, and lifting height, which are commonly referred to as the \"three key factors for lifting\". There is a mutually restrictive relationship among these three factors. The technical performance is typically expressed through lifting capacity curves or tables showing the corresponding lifting capacities. 　　Crawler cranes are characterized by their flexible operation; they can rotate 360 degrees and can move under load on flat, solid ground. Thanks to the tracks, it can operate on soft, muddy ground and travel on uneven surfaces. Currently, crawler cranes are widely used in the construction of prefabricated structures, especially in the installation of single-story industrial plant structures. The disadvantages of crawler cranes are poor stability; they should not be used for lifting heavy loads, they have a slow traveling speed, and their tracks can damage road surfaces. Therefore, they are usually transported using flatbed trailers when being moved from one location to another. 　　At present, the domestic crawler cranes commonly used in structural installation projects mainly include the following models: W1-50, W1-100, W1-100, Northwest 78D, etc. In addition, there are also some imported models. 　　1. W1-50 model: Its maximum lifting capacity is 100 KN (10 tons). It is operated using a hydraulic lever system, and the boom can be extended to 18 meters. This crane has a compact structure. As shown in Table 6-1 of the manual, the width of its track frame is M=2.85 m, while the distance from the rear of the crane to its rotation center is A=2.9 m. It has a low weight and high speed, allowing it to operate in relatively narrow spaces. It is suitable for lifting loads within a span of 18 meters and at a height of around 10 meters, as well as for performing various auxiliary tasks such as loading and unloading components. 　　2. W1-100 model: The maximum lifting capacity is 150 KN (15 tons). It is operated hydraulically. Compared with the W1-50 model, this crane has a larger frame; as shown in Table 6-1, the width of the track frame is M=3.2 m, and the distance from the rear of the crane to its rotation center is A=3.3 m. Its speed is relatively low, but thanks to its high lifting capacity and extended boom, it is suitable for lifting tasks in factories with a span of 18 m to 24 m. 　　3. W1-200 model: The maximum lifting capacity is 500 KN (50 tons). The main mechanisms are operated hydraulically, while the auxiliary mechanisms are controlled via levers and electrical systems. The boom can be extended to 40 meters. This crane has a particularly large structure; as shown in Table 6-1, the width of the track frame is M=4.05 m, and the distance from the rear of the crane to its rotation center is A=4.5 m. It is suitable for use in the installation work in large industrial facilities. 　　4. Stability verification of crawler cranes 　When a crawler crane is used for lifting heavy loads or when its boom is extended due to construction requirements, it is necessary to conduct a stability verification of the entire crane during operation in order to ensure its stability and prevent overturning accidents during lifting. After verification, if the requirements are not met, measures such as adding counterweights should be taken.