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The development of hydraulic concrete pumps in our country began in the late 1970s. Companies that produced fully hydraulic double-cylinder concrete pump trucks emerged from scratch, and more than 100 such small manufacturers of concrete pump trucks came into existence; the output of these pump trucks reached over a thousand units per year, which were then introduced to the market. Although the market is developing well, due to the imperfect production supervision system for concrete pumps in **, some manufacturers engage in imitation and shoddy manufacturing, resulting in a chaotic landscape in the concrete pump market. Based on years of professional experience, the author of this article offers several suggestions on how to determine the quality of concrete pump trucks, and on what aspects to consider in order to purchase high-quality, cost-effective concrete pump trucks with excellent performance, for everyone’s consideration. Features of concrete pumps (1) Trailer-mounted concrete transfer pumps have the following characteristics in construction: ① High degree of mechanization, requiring less labor and simplifying construction organization ； ②The transportation and pouring of concrete are continuous processes, resulting in high construction efficiency and rapid project progress ； ③The pumping process imposes strict requirements on the quality of concrete; it can be said that pumping serves as a form of quality inspection for concrete. Since pumping is carried out continuously, the concrete is less likely to separate during this process, and there is little loss in its slump, which makes it easier to ensure the quality of the construction work ； ④Job safety can reduce the risks during construction ； ⑤It has strong adaptability to construction sites and a wide range of application possibilities. The concrete delivery pipes can be laid in areas that are otherwise difficult to reach, and they enable concrete to be poured in place under certain pressure. Pumps can also be connected in series to increase the delivery distance and height, thus meeting various construction requirements ； ⑥It causes little interference with other construction machinery; other construction tasks can be carried out near the delivery pipe while pumping ； ⑦Under normal pumping conditions, the transportation of concrete in pipelines does not pollute the environment, meeting environmental protection requirements. (2) Using a portable concrete pump for construction also has certain limitations, which are mainly reflected in the following aspects: ④ In addition to meeting the requirements for project quality, the mix ratio of concrete must also satisfy the demands of pipeline transportation; there are specific requirements regarding factors such as the slump, the maximum size of concrete aggregates, and the proportions of cement and fine aggregates. ② The operators of the concrete pump need to have a certain level of technical expertise – they must not only know how to use and maintain the machinery but also possess knowledge of concrete construction techniques, enabling them to assess the quality and pumpability of the concrete. ③ The distance over which concrete can be transported is limited by the diameter of the delivery pipes, the performance of the pump’s distribution valves, and the outlet pressure ； ④It is difficult for drag-type concrete pumps to transport hard concrete, which limits their range of application ； ⑤Special measures are required to pump when the temperature is below -5°C. Classification of concrete pumps (1) Methods for classifying concrete pumps. Classified by the driving method of concrete pumps, there are piston-type and extrusion-type pumps; in addition, there are also hydraulic diaphragm pumps and air-cylinder pumps. At present, most are piston-type. Classified by the drive mechanism of concrete pumps: Among piston concrete pumps, there are mechanical piston pumps and hydraulic piston pumps, with hydraulic piston pumps being the most common nowadays. Hydraulic piston pumps can be further divided into water-pressure types and oil-pressure types depending on the medium used to drive the piston, with the majority being of the oil-pressure type. Classified by whether the pump can be moved: there are fixed concrete pumps, trailer-mounted concrete pumps, and vehicle-mounted concrete pumps, among which trailer-mounted and vehicle-mounted pumps are more commonly used. Classified by the type of directional control valve: there are rotary valves, gate valves, and S-shaped tube valves, among others; currently, gate valves and S-shaped tube valves are the most commonly used. (2) Advantages and disadvantages of gate valves and S-shaped tube valves. The main advantages of the gate valve concrete pump are its simple structure, ease of maintenance, high reversing force, and good material suction capacity. It requires less stringent conditions regarding the quality of concrete compared to S-shaped tube valve concrete pumps, and it can pump self-mixed concrete (suitable for pumping concrete with a low slump). However, the sealing performance of the gate valve is limited by its structure, resulting in lower sealing pressure. In construction, it is necessary to use Y-shaped pipes to connect the double cylinder body of the concrete pump to the delivery pipe, and such Y-shaped pipes cause significant pressure losses. Additionally, when using a gate valve for transportation, it is also required to install a horizontal conveying section in front of the vertical conveying pipeline, with a length of 1/2 of the concrete lifting height. This is because the gate is highly sensitive to the backflow caused by the fluid pressure exerted on the concrete in the vertical direction, which generates hydraulic resistance; such resistance reduces the height to which concrete can be pumped, and this is one of the main factors limiting the pumping height of concrete pumps equipped with gate valves. The main advantage of the S-shaped tube valve is that its swinging nozzle is flat, making it easy to adjust after wear; it also has excellent sealing properties, which is why S-shaped tube valve pumps can achieve a higher pumping height compared to gate valve pumps of the same specification. Designed using the parabolic principle to optimize the material flow and further reduce resistance, the AS-type pipe valve is currently the most widely used concrete distribution valve. Its main features are a simple structure, unobstructed flow channels, and low resistance to concrete flow ； Good sealing performance and high pumping pressure: The hopper is positioned low above the ground, which facilitates loading of concrete mixers into the hopper ； Fast commutation speed, low noise, etc. Main technical parameters of drag-type concrete pumps (1) Theoretical delivery volume. The theoretical value of the volume of concrete that can be transported by a concrete pump per hour (m3/h). Theoretical delivery volume Qt = Vt × n, where Vt is the theoretical volume per working stroke of the concrete pump (m3 per stroke), and n is the number of rated working strokes per hour of the concrete pump (strokes/h). (2) Actual delivery volume. The actual volume of concrete delivered by the concrete pump per hour (m3/h). The actual delivery volume Qa = Qt × Kv; the volumetric efficiency Kv ranges from 0.8 to 0.9. (3) Pressure of the pumped concrete. Concrete pressure at the outlet of the concrete pump during operation (MPa). Basic structure of a mobile concrete pump A mobile concrete pump is mainly composed of a main power system, a pumping system, and hydraulic and electrical control systems. (1) Primary power system. The prime movers for drag concrete pumps are diesel engines and electric motors; the advantage of diesel engine pumps is their strong adaptability. At some construction sites, the power supply is not sufficient to meet the high power demands of the machinery, as concrete pumps with large capacity typically require a power output of over 100 kW; in such cases, diesel engines can be used without having to worry about power supply issues. This is also precisely why diesel engine pumps have always been favored by users. The advantage of electric motor pumps is their low cost, as well as lower noise levels; this makes them an excellent choice for urban construction projects where environmental standards are increasingly strict. (2) Pumping system. This system is the actuator of a concrete pump, used to continuously transport the concrete mixture along the delivery pipeline to the pouring site. Generally, concrete pump operation modes include high-pressure with low flow rate and low-pressure with high flow rate; users can make a reasonable choice based on the project’s requirements regarding the height (or distance) at which the concrete needs to be delivered and the desired flow rate. The methods for switching between high and low pressure include replacing the rubber hose, rotating the valve block, and using a manual directional control valve. Most of the newly developed products utilize fully automatic high/low pressure switching technology; by turning an electronic control button, the switch between high and low pressure can be completed in an instant, offering speed and convenience. Furthermore, the new products often employ an automatic piston retraction system: by simply pressing a button, the concrete piston can be retracted into the water tank. This technology helps to **reduce the time required to install and remove the concrete piston, thereby lowering the workload on the operators ； At any necessary time, the concrete piston can also be removed in order to check for wear on the concrete seal, or to clean and maintain it, thereby extending the piston’s service life. (3) Hydraulic and electrical control systems. Hydraulic systems are divided into open systems and closed systems; open systems have the advantages of lower hydraulic oil temperature and higher cleanliness ； Closed systems have the advantages of a small hydraulic oil tank and a compact design; most domestic products use these two types of systems. Electronic control systems are generally controlled by PLCs; some products are also equipped with text displays and touch buttons, providing a good human-machine interaction interface. Sensors distributed throughout various parts of the concrete pump send signals to the PLC controller, which displays the operating status of the concrete pump via a text display. When an anomaly occurs, the built-in protection program in the system is activated immediately to protect the concrete pump from damage. At the same time, the cause of the fault is displayed on the text monitor, facilitating fault diagnosis and repair. A comprehensive analysis of brands and services: It is not difficult to make a choice based on the “hardware” specifications of pumps, but an analysis from a “software” perspective is also necessary. The main configurations of concrete pumps on the market vary little; the biggest differences lie in the reliability of the products and the after-sales service provided by the manufacturers. Our company has obtained ISO9001:2000 quality system certification and boasts strong technical capabilities; it is the largest construction machinery repair center in Shandong, offering worry-free after-sales service.