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Analysis of Design and Manufacture Technology of Concrete Pump Car Chassis
Concrete pump truck chassis is primarily composed of a rotary base, legs, swing cylinder, and telescopic cylinder. As the main load-bearing component, the chassis structure is typically designed as a box-shaped frame, which also incorporates internal fuel and water tanks. The rationality of this design directly affects the reliability, stability, and overall weight of the concrete pump. At the BAUMA CHINA 2004 International Expo, numerous well-known domestic and international companies showcased their latest products and high-quality solutions, reflecting not only their technological capabilities but also the current state of chassis design and manufacturing. With the rapid development of China’s construction machinery industry, the gap between domestic and foreign advanced technologies in concrete pump chassis design has significantly narrowed. Domestic manufacturers have made considerable progress in structural design and technical research, drawing on years of experience in pump part design and production, as well as participation in major exhibitions. This provides a solid foundation for discussing the current status of concrete pump chassis technology in China and the challenges it still faces compared to global standards.
First, the characteristics of the concrete pump chassis structure and its main connections.
The chassis structure mainly consists of the rotary base and outriggers. The rotary base serves as the main support, bearing the weight and vibrations from the boom. The outriggers are crucial for ensuring the safety and stability of the pump during operation. Unlike cranes, concrete pumps do not have counterweights, so when the boom extends horizontally, a large overturning moment is generated. These moments are mainly balanced by the reaction force of the outriggers. Therefore, the outriggers must have sufficient structural dimensions and support area. Both the rotary base and legs need to possess adequate strength and fatigue resistance.
Chassis structures can be categorized based on the leg extension mechanism: swing-type front and rear legs, telescopic front and rear legs, and the former type with telescopic swing legs.
Swing-type front and rear legs allow the legs to pivot around a central point, offering good stability and a simple structure. However, they require sufficient space on both sides of the vehicle, which may limit their use in certain environments. Due to constraints on the vehicle's overall size and stability, most domestic and international manufacturers adopt this structure.
Telescopic front and rear legs, also known as XH legs, enable horizontal extension and retraction within the box-shaped frame of the rotary base. The left and right legs can cross in an X-shape or extend parallelly. However, due to limitations in vehicle width and the need for high-precision manufacturing of the box frame, these structures tend to be heavier and more complex. They also require built-in fuel tanks, making disassembly and maintenance difficult. As a result, very few manufacturers produce models over 37 meters. This structure was commonly used in the early stages of pump truck development, but some manufacturers still utilize it due to its flexible working space, such as Italy’s CIFA 37 m and MEBC 037 m models.
The front telescopic swinging leg structure features a telescopic supporting leg connected to the front of the rotary base and a swinging leg at the rear. Combining the advantages of the previous two designs, this structure reduces weight and allows for narrower working spaces, leading to increasing adoption by manufacturers. In 2004, XCMG Heavy Industry became the first Chinese company to launch the HB40 model using this structure. Foreign manufacturers, such as Germany’s PM Company for models up to 42 m and Korea’s models up to 40 m, also widely use similar designs.
Second, the challenges and key priorities in the design and manufacturing of concrete pump chassis.
As the main connection component, the rotary base is structurally complex, requiring not only dynamic strength and rigidity but also welds that can withstand vibration. Accurately calculating the stress distribution of the entire rotary base is a major design challenge. XCMG has conducted extensive research on finite element analysis, successfully exploring methods for calculating the rotary base and accumulating valuable design experience. Additionally, the interior of the rotary base often includes a fuel tank and water tank. Preventing delayed cracking in the welding areas is a significant manufacturing challenge, as is ensuring the integrity of the weld joints. Magnetic particle inspection combined with kerosene leakage detection, along with ultrasonic testing, are effective methods. Domestic manufacturers evaluate various approaches based on their equipment and choose the most economically viable solution.
In normal conditions, the swivel ring and swivel reducer are connected in the swivel area of the chassis. To ensure proper meshing of the swivel reducer and support, the swivel parts are designed with higher rigidity. All manufacturers have explored effective solutions, with the most common being the reinforcement of thin ring plates and thick seat plate connections.