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1) Main structure and pumping principle. Introduce its structural features and pumping principle.: As shown in the picture: HBT60 concrete delivery pump consists of hopper, pumping system, hydraulic system, cleaning system, electrical system, motor, traveling chassis, etc. Its pumping system is shown in the figure: The pumping mechanism consists of two main cylinders 1 and 2 water tanks 3, reversing device 4, two concrete cylinders 5 and 6, two concrete pistons 7 and 8, hopper 9, distribution valve 10 (S-shaped valve), swing arm 11, two swing cylinders 12 and 13 and a discharge port 14. The concrete pistons (7, 8) are connected to the piston rods of the main oil cylinder (1, 2) respectively. Under the action of the hydraulic oil of the main oil cylinder, they make reciprocating movements. When one cylinder moves forward, the other cylinder moves backward. ； The outlet of the concrete cylinder is connected to the hopper. One end of the distribution valve is connected to the outlet, and the other end can be connected to the swing arm through a spline shaft. It can swing left and right under the action of the swing cylinder. When pumping concrete material, under the action of the main oil cylinder, the concrete piston 7 advances and the concrete piston 8 retreats. At the same time, under the action of the swing oil cylinder, the distribution valve 10 is connected to the concrete cylinder 5 and the concrete cylinder 6 is connected to the hopper. In this way, the concrete piston 8 retreats to suck the concrete in the hopper into the concrete cylinder, and the concrete piston 7 advances to send the concrete material in the concrete cylinder into the distribution valve and pump it out. When the concrete piston 8 retreats to the end of the stroke, the reversing device 4 in the water tank 3 is triggered, and the main cylinders 1 and 2 are reversed. At the same time, the swing cylinders 12 and 13 are reversed, so that the distribution valve 10 is connected to the concrete cylinder 6, and the concrete cylinder 5 is connected to the hopper. At this time, the piston 7 retreats and the piston 8 advances. Daily cycle, thus achieving continuous pumping. During reverse pump operation, the concrete cylinder in the suction stroke is connected to the distribution valve, and the concrete cylinder in the push stroke is connected to the hopper, thereby pumping the concrete in the pipeline back to the hopper (as shown in the figure). The pumping system completes the suction and discharge of concrete through the switching of the distribution valve. Therefore, the distribution valve is a key component of the concrete pump, and its type will directly affect the performance of the concrete pump. 2) Several common distribution valve types (1) Vertical axis butterfly valve (as shown in the figure) A butterfly plate is set on the channel between the hopper, concrete cylinder and concrete pump outlet. The butterfly plate flips under the push of the hydraulic cylinder piston rod, so that the working cylinders 3 and 4 have different channels from the delivery pipe 2 and the collecting hopper. The valve has the characteristics of simple structure, small volume, short concrete flow path, small reversing resistance and easy maintenance. Because the cross-sectional area of the concrete flow channel changes greatly and the direction of the suction flow channel mouth changes drastically, the pumping resistance in the distribution valve is large, so the concrete pumping pressure is small and the service life is long. (2) S-shaped valve (as shown in the figure) The S-shaped valve is placed in the hopper. One end of the S-shaped valve is connected to the outlet of the concrete pump. The other end swings back and forth under the action of the two hydraulic cylinder piston rods. It is connected to the two concrete cylinders A and B respectively. When the S-shaped valve is connected to the concrete pump cylinder B, when the pump cylinder B pressurizes concrete, cylinder A will suck in the concrete. ； When the S-shaped valve is connected to concrete pump cylinder A, cylinder A pressurizes and cylinder B sucks concrete, thus realizing the process of suction and discharge. The S-shaped valve itself is a part of the delivery pipe, and the cross-sectional shape does not change when it flows, and a wear-resistant plate with a wear-resistant ring is installed. Consumable parts are easy to repair and replace after wear. Due to the high pressure of pumping concrete, it has the characteristics of long transportation distance and high transportation height. (3) C-shaped valve (as shown in the figure) The C-shaped valve is placed in the hopper, one end is connected to the concrete pump outlet 10, and the other end swings back and forth under the action of the two hydraulic cylinder piston rods, and is connected to the two concrete cylinders 7 respectively to realize the material suction and discharge processes. The application of this valve can have the following characteristics: It is easy to remove residual concrete. When cleaning the entire conveying system after pumping concrete, the sponge ball can be pumped back to clean the conveying pipe without opening the conveying pipe. ； C-shaped valve is easy to replace ； The contact surface between the wear-resistant plate and the C-shaped valve can automatically compensate for the wear amount by an automatic sealing ring ； The C-shaped valve is made of thick manganese steel and is wear-resistant. ； There is no swing shaft similar to the S-shaped valve, and the concrete can flow directly into the concrete cylinder, with high suction efficiency. ； The C-shaped valve bearings are located outside the concrete area, eliminating frequent maintenance ； Strong adaptability to aggregates, etc. 4) Inclined gate valve (as shown in the figure) This valve is set at the rear of hopper 1, which can not only reduce the height of the hopper, but also make the pump body compact without preventing the mixer truck from unloading materials into the hopper. Each of the two hydraulic cylinders has a gate valve, which makes reciprocating motion under the action of the hydraulic cylinder piston to complete the action of opening or closing the inlet and outlet of the concrete. This valve has strong adaptability to concrete, but its structure is complicated. When replacing this valve, the hopper needs to be removed, so maintenance is inconvenient. The discharge return uses a Y-shaped pipe, which has a large pressure loss, so the pressure of pumping concrete is small. The grease used to lubricate the gate valve during operation can easily enter the concrete, so it is a consumable and needs to be constantly replenished.