A double concrete piston automatic return system for concrete pumping mechanism

Abstract

The present invention discloses an automatic retraction system for dual concrete pistons in a concrete pumping mechanism, comprising dual concrete piston cylinders, an oil output control circuit, a back pressure circuit, an oil inlet control valve, and a power pump group. The oil output control circuit connects the rodless chambers of the two concrete piston main oil cylinders and the oil tank, and is used to control the on-off connection between the rodless chambers of the two concrete piston cylinders and the oil tank. The back pressure circuit is connected in parallel to the oil output control circuit and is connected to the oil tank, and is used to provide control pressure for the oil output control circuit. The oil inlet control valve connects the rod chambers of the two concrete piston main oil cylinders and the oil tank, and is used to control the on-off connection between the rod chambers of the two concrete piston cylinders and the oil tank when the two concrete piston rods retract. The power pump group provides power for the movement of the oil. The present invention provides an automatic retraction system for dual concrete pistons in a concrete pumping mechanism, which solves the problem in the prior art that when the retraction function is achieved through a ball valve, the ball valve has poor sealing performance, leading to internal leakage, causing oil cross-talk during pumping, affecting the stability of the hydraulic system, and causing short-stroke failures.

Description

Technical Field

[0001] The invention relates to an automatic retraction system of double concrete pistons of a concrete pumping mechanism, belonging to the technical field of hydraulic systems. Background Art

[0002] Concrete pump: An energy conversion device that converts hydraulic energy into the pressure energy of flowing concrete;

[0003] Master cylinder: An energy conversion device that converts hydraulic energy into mechanical energy. The master cylinder is connected to the concrete piston and can convert hydraulic energy into kinetic energy (potential energy) of concrete.

[0004] Concrete piston: a disc-shaped component that reciprocates in the concrete cylinder to pressurize the concrete mixture;

[0005] The concrete pumping mechanism is the core of a concrete pump truck, responsible for continuously pumping concrete along the delivery pipeline to the pouring site. It typically features a dual-piston, dual-cylinder pumping mechanism. This mechanism utilizes two main cylinders, one advancing while the other retreats, pumping concrete drawn into the delivery cylinders to the discharge port. Driven by their respective main cylinders, the two delivery cylinders alternately operate, one drawing in concrete while the other pumps it out. When the main cylinder reaches the end of its stroke, it reverses direction, causing the two delivery cylinders to reverse direction, with the cylinder drawing in concrete becoming the one pumping it, and the cycle continues, continuously pumping concrete.

[0006] During the use of the concrete pump, the concrete piston reciprocates in the concrete cylinder for a long time. As a wearing part, it often needs to be repaired or replaced. In addition, when troubleshooting some faults, it is necessary to replace the concrete piston, the delivery cylinder, the main oil cylinder seal, etc. At this time, the two concrete pistons need to be returned to the water tank. How to return the two concrete pistons at one time easily and quickly is particularly important.

[0007] The existing traditional method is to use a ball valve to send two pumps to the main to realize the automatic return function of the double piston. However, due to the poor sealing of the ball valve, there will be a certain amount of internal leakage. During normal pumping, it will cause oil leakage, affect the stability of the hydraulic system, and even cause short stroke and other faults. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the existing technology and provide a double concrete piston automatic retraction system for a concrete pumping mechanism, so as to solve the problem that when the traditional method in the existing technology realizes the retraction function through a ball valve, the ball valve has poor sealing performance, resulting in internal leakage, causing oil leakage when the pump is pumped, affecting the stability of the hydraulic system and causing short-stroke failures.

[0009] To achieve the above purpose, the present invention provides a double concrete piston automatic retraction system for a concrete pumping mechanism, comprising a double concrete piston cylinder, an oil output control circuit, a back pressure circuit, an oil inlet control valve and a power pump group;

[0010] The oil output control circuit connects the rodless chambers of the two concrete piston master cylinders and the oil tank, and is used to control the on / off of the rodless chambers of the two concrete piston cylinders and the oil tank;

[0011] The back pressure circuit is connected in parallel to the oil output control circuit and is connected to the oil tank to provide control pressure for the oil output control circuit;

[0012] The oil inlet control valve is connected to the rod chambers of the two concrete piston master cylinders and the oil tank, and is used to control the on-off between the rod chambers of the two concrete piston cylinders and the oil tank when the two concrete piston rods retract;

[0013] The power pump group provides power for the movement of the oil.

[0014] Furthermore, the oil output control circuit includes a first slide valve and a first solenoid valve, and the first slide valve is a double-sided slide valve;

[0015] The oil inlet port of the first slide valve is connected to the rodless chambers of the two concrete piston cylinders, and the oil outlet port of the first slide valve is connected to the oil tank, the first solenoid valve and the back pressure circuit;

[0016] The oil inlet port of the first solenoid valve is connected to the oil outlet port of the first slide valve and the power pump group, the oil outlet port of the first solenoid valve is connected to the oil tank, and the working port of the first solenoid valve is connected to the control port of the first slide valve, which is used to control the action of the first slide valve through the action of the first solenoid valve to control the connection and disconnection of the rodless chambers of the two concrete piston cylinders and the oil tank;

[0017] The control pressure provided by the back pressure circuit is greater than the operating pressure of the first spool valve control port.

[0018] Furthermore, the first slide valve comprises at least a first station and a second station;

[0019] The first sliding valve is provided with at least two oil inlet ports, which are respectively connected to the rodless chambers of the two concrete piston cylinders;

[0020] The first sliding valve is provided with at least two oil outlet ports, one of which is connected to the oil tank, and the other is connected to the first solenoid valve and the back pressure circuit.

[0021] Furthermore, in the first working position of the first sliding valve, the oil inlet port and the oil outlet port are disconnected;

[0022] The second position of the first sliding valve is provided with at least two connected oil inlet ports and oil outlet ports, one for connecting to the oil tank, and the other for connecting to the first solenoid valve and the back pressure circuit.

[0023] Furthermore, the first solenoid valve comprises at least a first working position and a second working position, and the first solenoid valve is provided with at least two working ports;

[0024] In the first working position of the first solenoid valve, the oil inlet port, the oil outlet port and the working oil port are connected;

[0025] In the second position of the first solenoid valve, the oil inlet port is disconnected from the oil outlet port, two working oil ports are set, the oil inlet port and the oil outlet port are respectively connected to a working oil port, and the two working oil ports are respectively connected to the first slide valve control port.

[0026] Furthermore, the back pressure circuit includes a second relief valve and a second solenoid valve;

[0027] The second relief valve is connected in parallel to the first solenoid valve, and is used to increase the system pressure of the oil output control circuit. The working pressure of the second relief valve is greater than the working pressure of the first slide valve control port.

[0028] The oil inlet port of the second relief valve and the oil inlet port of the first solenoid valve are commonly connected to the power pump group and the oil outlet port of the first slide valve, and the oil outlet port of the second relief valve is connected to the oil tank.

[0029] Furthermore, the second solenoid valve is arranged at the oil inlet port of the second overflow valve, and the second solenoid valve is used to control the oil supply state of the second overflow valve.

[0030] The beneficial effects achieved by the present invention are:

[0031] The present invention solves the problem of poor sealing of ball valves in the prior art by adopting a third solenoid valve instead of a ball valve between the rod chamber and the oil cylinder of the two concrete piston cylinders. It can effectively reduce internal leakage, effectively avoid oil cross-contamination during normal pumping, and improve the stability of the hydraulic system.

[0032] The present invention connects a first solenoid valve to a first slide valve control port, and controls the on-off of the return oil of the two concrete piston cylinders and the oil cylinder through the reversing action of the first solenoid valve; in the present invention, the oil inlet port of the first solenoid valve is connected to the first slide valve, and the oil discharged from the two concrete piston pumps output by the first slide valve supplies oil to the first solenoid valve, so that the oil pressure of the present invention is controlled from the main system pressure when performing a double-cylinder return operation, without the need to introduce an external oil source, which can effectively save system costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a hydraulic system diagram of a double concrete piston automatic retraction system of a concrete pumping mechanism provided by an embodiment of the present invention;

[0034] In the figure: 100, the first solenoid valve; 200, the second solenoid valve; 300, the second overflow valve; 400, the third solenoid valve; 500, the double concrete piston cylinder; 600, the first slide valve. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0036] The embodiment of the present invention provides a concrete pumping mechanism double concrete piston automatic retraction system, such as Figure 1 As shown, this automatic retraction system is used in a double concrete piston concrete pumping mechanism when the double concrete piston cylinder 500 needs to be retracted, to assist the retraction of the double concrete piston cylinder 500, including a double concrete piston cylinder 500, an oil outlet control circuit, a back pressure circuit, an oil inlet control circuit and a power pump group; compared with the prior art, the present invention sets an oil outlet control circuit and a back pressure circuit in the double concrete piston cylinder 500 concrete pumping mechanism, and the oil outlet control circuit and the back pressure circuit are both internal control circuits, and the control oil pressure comes from the system pressure, without the need for an external oil source and a control valve, which simplifies the system and reduces the system cost; compared with the prior art, the present invention uses an electromagnetic valve instead of a ball valve, which can effectively improve the sealing of the hydraulic system, reduce internal leakage, effectively avoid oil leakage during normal pumping, and improve the stability of the hydraulic system.

[0037] like Figure 1 As shown, in an automatic retraction system of double concrete pistons in a concrete pumping mechanism provided by an embodiment of the present invention, the oil outlet control circuit connects the rodless chambers of the two concrete piston master cylinders and the oil tank, and the oil outlet control circuit is used to control the on-off of the rodless chambers of the two concrete piston master cylinders and the oil tank. When the device is to retract the piston, the oil outlet control circuit is actuated to control the connection between the rodless chambers of the two concrete piston master cylinders and the oil tank, so that the oil in the rodless chambers of the two concrete piston master cylinders flows back to the oil tank through the oil outlet control circuit to complete the retraction operation of the two concrete pistons.

[0038] To achieve the above-mentioned operational purpose, an embodiment of the present invention provides an oil output control circuit including a first slide valve 600, which is used to control the on-off of the rodless chambers of the two concrete piston cylinders and the oil tank. Therefore, the first slide valve 600 includes at least a first position and a second position. The first slide valve 600 includes an oil tank connection port and a piston connection port. In the first position and the second position of the first slide valve 600, the on-off conditions of the connection port and the piston connection port are different. By controlling the first slide valve 600 to switch between the first position and the second position, the on-off purpose of the rodless chambers of the two concrete piston cylinders and the oil tank is achieved; to achieve the above-mentioned purpose, in an embodiment of the present invention, when performing specific product design, the first slide valve 600 can select a three-position four-way hydraulically controlled bilateral slide valve, the two side positions of the first slide valve 600 are the second position, the middle position is the first position, and the middle position is the normal position, and its position function is "O" type.

[0039] As mentioned above, in the present invention, the oil output control circuit is an internal control circuit. In the oil output control circuit, the first slide valve 600 is actuated to control the on-off of the rodless chambers of the two concrete piston cylinders and the oil tank. In order to realize the control of the first slide valve 600 by internal control, the control circuit also includes a first solenoid valve 100. The first solenoid valve 100 is connected to the control port of the first slide valve 600 and is used to provide hydraulic control power for the first slide valve 600 to change the working position. The first solenoid valve 100 includes at least a first workstation and a second workstation. The first solenoid valve 100 includes a working port, an oil inlet port and an oil outlet port. The oil inlet port is connected to the hydraulic pump and The oil outlet of the first spool valve 600 is used to receive hydraulic oil as power. The oil outlet port is connected to the oil tank, and the working port is connected to the control end of the first spool valve 600. In the first working position of the first solenoid valve 100, the working port and the oil inlet port are both connected to the oil outlet port. In the second working position of the first solenoid valve, the oil inlet port is disconnected from the oil outlet port, and the oil inlet port and the oil outlet port are respectively connected to the working port. By controlling the first solenoid valve 100 to switch between the first working position and the second working position, the control port of the first spool valve 600 is controlled, and the first spool valve 600 is switched in the internal control state. To achieve the above purpose, in the embodiment of the present invention, when designing the product, the first solenoid valve 100 is a three-position four-way electromagnetic reversing valve. The two side positions of the first solenoid valve 100 are the second working position, the middle position is the first working position, and the middle position is the normal position. The middle position function is "H" type.

[0040] Based on the above-mentioned arrangement of the present invention, when the two concrete pistons need to be retracted, the first solenoid valve 100 is energized and activated, and the first solenoid valve 100 is switched to the second working position. The oil inlet port of the first solenoid valve 100 is connected to the working port, and the oil inlet port is disconnected from the oil outlet port. The control oil flows into the control port of the first slide valve 600 through the oil inlet port and the working port of the first solenoid valve 100. The control port of the first slide valve 600 obtains the control oil, and the first slide valve 600 is activated and switched to the second working position. The oil tank connection port and the piston connection port of the first slide valve 600 are connected, and the oil in the rodless chamber of the double concrete piston cylinder 500 flows into the oil tank through the oil tank connection port and the piston connection port of the first slide valve 600 to realize the retraction operation of the two concrete pistons.

[0041] The two rod cavities in the double concrete piston cylinder 500 are connected. When the double concrete piston cylinder 500 works alternately, the oil in the two rod cavities in the double concrete piston cylinder 500 circulates with each other to realize the back and forth alternating movement of the double concrete pistons. However, this hinders the return of the two concrete piston rods. In an embodiment of the present invention, in order to solve this problem, after the rod cavities of the two concrete piston cylinders are connected, a third solenoid valve 400 is connected. One end of the third solenoid valve 400 is connected to a hydraulic pump. The third solenoid valve 400 includes at least a first station and a second station. The third solenoid valve 400 includes an oil inlet port and an oil outlet port. The third solenoid valve The oil inlet port of 400 is connected to the oil tank, and the oil outlet port of the third solenoid valve 400 is connected to the rod chambers of the two concrete piston cylinders. The on-off conditions of the oil inlet port and the oil outlet port in the first and second stations of the third solenoid valve 400 are different. When the two concrete piston rods perform alternating operations back and forth, the oil inlet port and the oil outlet port of the third solenoid valve 400 are disconnected. When the two concrete piston rods need to be retracted, the oil inlet port and the oil outlet port of the third solenoid valve 400 are connected, and the hydraulic oil is pumped by the hydraulic pump, and then supplied to the rod chambers of the two concrete piston cylinders through the oil inlet port and the oil outlet port of the third solenoid valve 400, thereby assisting the two concrete piston rods in performing the retraction operation. In an embodiment of the present invention, in order to achieve the above-mentioned purpose, the third solenoid valve 400 uses a two-position two-way solenoid valve, the oil inlet port and the oil outlet port are disconnected in the first position, and the other is the second position. Since the two concrete piston rods are retracted for rest and maintenance, which takes a short time, and most of the time they are in alternating telescopic movement, the first position of the third solenoid valve 400 is set to the normal position. When the two concrete piston rods need to be retracted, the third solenoid valve 400 is actuated and switched to the second position. The oil enters the rod cavity of the two concrete piston cylinders, pushing the two piston rods to retract.

[0042] When the two concrete piston rods are retracted, the concrete pumping mechanism is shut down, and the hydraulic pump used to push the two concrete pistons to perform alternating motion is in a small displacement operation state, which cannot ensure that the hydraulic oil connected to the control port of the first slide valve 600 has sufficient pressure to push the first slide valve 600 to switch the work position. At the same time, in order to ensure that the two concrete piston rods have sufficient action pressure, a first relief valve with a larger back pressure is provided in the main circuit. However, due to the large back pressure of the first relief valve, if the back pressure of the first relief valve is used as the system pressure when the two concrete piston rods are retracted, it will cause the two concrete piston cylinders to have fluid pressure. The pressure in the rod chamber is lower than the pressure in the rodless chamber, which causes the two concrete piston cylinders to be unable to retreat. To solve this problem, the present invention sets a back pressure circuit to increase the oil pressure of the hydraulic system while not making the pressure in the rodless chamber of the two concrete piston cylinders greater than the pressure in the rod chamber, ensuring that there is enough pressure to push the first sliding valve 600 to move while ensuring that the two concrete piston rods can retreat. To achieve the above purpose, in an embodiment of the present invention, the back pressure circuit includes a second relief valve 300, which is used as a back pressure valve. The second relief valve 300 is connected in parallel with the first relief valve. The second relief valve 300 is shown in FIG. The working pressure of the relief valve 300 is lower than that of the first relief valve. The oil inlet port of the second relief valve 300 is connected to the main oil circuit, and the oil outlet port of the second relief valve 300 is connected to the oil tank. Since the first relief valve and the second relief valve 300 are connected in parallel, in order to ensure that the working system of the first relief valve is at a higher pressure when the two concrete piston rods are in action and the working system of the second relief valve 300 is at a lower pressure when the two concrete piston rods are retracted, the embodiment of the present invention provides a second solenoid valve 200 at the oil inlet port of the second relief valve 300 for controlling the connection and disconnection of the second relief valve 300 and the main oil circuit. In an embodiment of the present invention, the second solenoid valve 200 is a two-position three-way solenoid valve. When it is in its normal position, the second relief valve 300 is disconnected from the main oil circuit, and the pressure of the main oil circuit is the working pressure of the first relief valve, so the normal position is used in the working state of the double concrete piston rod; when it is in its working position, the second relief valve 300 is connected to the main oil circuit. Since the working pressure of the second relief valve 300 is less than the working pressure of the first relief valve, the working pressure of the main oil circuit system is the working pressure of the first relief valve, so the working position of the second relief valve 300 is used in the working state of the double concrete piston rod retreating.

[0043] Specifically, let the working pressure of the second overflow valve 300 be P1, the pressure of the hydraulic oil output by the constant pressure pump to the rod chamber of the two concrete piston cylinders be P2, the area of ​​the rod chamber piston is A1, and the area of ​​the rodless chamber piston is A2. When designing the system, in order to ensure that the concrete piston rod can retract, the following design requirements should be met: P2*A1 is greater than or equal to P1*A2.

[0044] like Figure 1 As shown in the figure, when the two concrete piston rods are retracted, the working process is as follows:

[0045] When it is necessary to retract the two concrete piston rods, the double concrete piston concrete pumping mechanism is on standby, the displacement of the hydraulic pump is reduced, the first solenoid valve 100 is energized and enters the second working position, the second solenoid valve 200 is energized and enters the second working position, and the third solenoid valve 400 is energized and enters the second working position. At this time, the oil output by the hydraulic pump enters the second relief valve 300 through the second solenoid valve 200, and flows into the oil tank after reaching the relief pressure P1. At the same time, the pressure of the entire oil circuit system is increased to P1, and the oil enters the control port of the first slide valve 600 through the first solenoid valve 100. The first slide valve 600 is actuated and enters the second working position. At this time, the rodless chambers of the two concrete piston cylinders are connected to the oil tank through the second slide valve, and the oil in the rodless chambers of the two concrete piston cylinders flows into the oil tank after passing through the second slide valve, completing the retraction of the two concrete piston rods.

[0046] Since this device is used to retract the double concrete pistons when the double concrete piston concrete pumping mechanism is maintained, this device is set in the working hydraulic system of the double concrete pistons. The hydraulic pump used to provide control pressure for the first sliding valve 600 is a variable pump. When the double concrete piston concrete pumping mechanism performs pumping operation, the second solenoid valve 200 disconnects the second relief valve 300 from the main oil circuit, the working pressure of the first relief valve is the system pressure, the third solenoid valve 400 disconnects the oil tank from the rod chambers of the two concrete piston cylinders, and the two concrete pistons perform alternate pumping operations; when the double concrete piston rods need to be maintained, the second solenoid valve 200 connects the second relief valve 300 to the main oil circuit, the working pressure of the second relief valve 300 is the system pressure, the third solenoid valve 400 connects the oil tank to the rod chambers of the two concrete pistons, and the two concrete pistons perform retraction operations.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A double concrete piston automatic retraction system for a concrete pumping mechanism, characterized by: It includes a double concrete piston cylinder (500), an oil output control circuit, a back pressure circuit, an oil inlet control valve and a power pump group; The oil output control circuit is connected to the rodless chamber of the double concrete piston cylinder (500) and the oil tank, and is used to control the on / off of the rodless chamber of the double concrete piston cylinder (500) and the oil tank; the oil inlet control valve is a third solenoid valve (400); The back pressure circuit is connected in parallel to the oil output control circuit and is connected to the oil tank to provide control pressure for the oil output control circuit; The oil inlet control valve is connected to the rod chamber of the double concrete piston cylinder (500) and the oil tank, and is used to control the connection and disconnection between the rod chamber of the double concrete piston cylinder (500) and the oil tank when the two concrete piston rods retract; The power pump group provides power for the movement of oil; The oil output control circuit comprises a first slide valve (600) and a first solenoid valve (100), wherein the first slide valve (600) is a double-sided slide valve; The oil inlet port of the first slide valve (600) is connected to the rodless chamber of the double concrete piston cylinder (500), and the oil outlet port of the first slide valve (600) is connected to the oil tank, the first solenoid valve (100) and the back pressure circuit; The oil inlet port of the first solenoid valve (100) is connected to the oil outlet port of the first slide valve (600) and the power pump group, the oil outlet port of the first solenoid valve (100) is connected to the oil tank, and the working port of the first solenoid valve (100) is connected to the control port of the first slide valve (600), so as to control the action of the first slide valve (600) through the action of the first solenoid valve (100) to control the on-off of the rodless chamber of the double concrete piston cylinder (500) and the oil tank; The control pressure provided by the back pressure circuit is greater than the operating pressure of the control port of the first slide valve (600); The first sliding valve (600) comprises at least a first station and a second station; The first sliding valve (600) is provided with at least two oil inlet ports, which are respectively connected to the rodless chambers of the double concrete piston cylinder (500); The first sliding valve (600) is provided with at least two oil outlet ports, one of which is connected to the oil tank, and the other is connected to the first solenoid valve (100) and the back pressure circuit; In the first working position of the first sliding valve (600), the oil inlet port and the oil outlet port are disconnected; The second station of the first slide valve (600) is provided with at least two connected oil inlet ports and oil outlet ports, one for connecting to the oil tank and the other for connecting to the first solenoid valve (100) and the back pressure circuit; The first solenoid valve (100) comprises at least a first working position and a second working position, and the first solenoid valve (100) is provided with at least two working ports; In the first working position of the first solenoid valve (100), the oil inlet port, the oil outlet port and the working oil port are connected; In the second working position of the first solenoid valve (100), the oil inlet port and the oil outlet port are disconnected, two working oil ports are provided, the oil inlet port and the oil outlet port are respectively connected to a working oil port, and the two working oil ports are respectively connected to the control port of the first slide valve (600); The back pressure circuit includes a second overflow valve (300) and a second solenoid valve (200); The second relief valve (300) is connected in parallel to the first solenoid valve (100) and is used to increase the system pressure of the oil output control circuit. The working pressure of the second relief valve (300) is greater than the working pressure of the control port of the first slide valve (600); The oil inlet port of the second relief valve (300) and the oil inlet port of the first solenoid valve (100) are commonly connected to the oil outlet of the power pump group and the first slide valve (600), and the oil outlet port of the second relief valve (300) is connected to the oil tank; The working pressure of the second overflow valve (300) is P1, the pressure of the hydraulic oil output by the constant pressure pump to the rod chamber of the double concrete piston cylinder (500) is P2, the area of ​​the rod chamber piston is A1, and the area of ​​the rodless chamber piston is A2, and the following design requirements are also included: P2×A1 is greater than or equal to P1×A2; When the two concrete piston rods need to be retracted, the first solenoid valve (100) is energized to enter the second working position, the second solenoid valve (200) is energized to enter the second working position, and the third solenoid valve (400) is energized to enter the second working position. At this time, the oil output by the hydraulic pump enters the second overflow valve (300) through the second solenoid valve (200), and flows into the oil tank after reaching the pressure P1. At the same time, the pressure of the entire oil circuit system is increased to P1. The oil enters the control port of the first slide valve (600) through the first solenoid valve (100). The first slide valve (600) is actuated to enter the second working position. At this time, the rodless chamber of the double concrete piston cylinder (500) is connected to the oil tank through the first slide valve, and the oil in the rodless chamber of the double concrete piston cylinder (500) flows into the oil tank after passing through the first slide valve.

2. The double concrete piston automatic retraction system of a concrete pumping mechanism according to claim 1 is characterized in that: The second solenoid valve (200) is arranged at the oil inlet port of the second relief valve (300), and the second solenoid valve (200) is used to control the oil supply state of the second relief valve (300).

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