Telescopic arm control method and system of horizontal bar bolt crane

Abstract

The invention relates to the technical field of cranes, and provides a telescopic arm control method and system of a horizontal bar bolt crane, and the telescopic arm control method comprises the following steps: receiving a first control instruction of a telescopic arm; calculating the target length of the telescopic arm; each arm section is controlled to run to the corresponding target position in a decelerating mode, and when the current arm section runs to the corresponding target position, an arm pin of the current arm section is controlled to be inserted into an arm pin hole of the corresponding outer sleeve arm section; the current arm section is controlled to retract until the arm pin makes contact with the lower end of the arm pin hole, and the arm extending action of the arm section is completed; after the telescopic arm is in place, the current arm section is retracted by a certain distance, so that the arm pin of the current arm section is in contact with the lower end of the arm pin hole, when the subsequent telescopic arm is retracted, the arm section needs to be pushed forwards to conveniently release the connection between the arm pin and the arm pin hole, and in this way, the bearing force is provided for the arm section; therefore, no impact sound is generated when the arm is contracted.

Description

Technical Field

[0001] The present invention relates to the technical field of cranes, and in particular to a telescopic arm control method and system of a horizontal bar latch crane. Background Art

[0002] Most multi-arm cranes use a single-cylinder pin-type telescopic mechanism, which realizes the telescopic function of the telescopic arm through the cooperation of the telescopic cylinder, cylinder pin, arm pin, and a cylinder-arm pin driving mechanism having a cylinder pin cylinder and an arm pin cylinder. Among them, the cylinder pin cylinder drives the cylinder pin to be inserted and pulled out to control the locking or separation of the telescopic part of the telescopic cylinder and the arm section of the telescopic arm, and the arm pin cylinder drives the arm pin to be inserted and pulled out to control the locking or separation of two adjacent arm sections. When a certain arm section needs to be extended, the cylinder pin cylinder first drives the cylinder pin to move to lock the telescopic cylinder and the arm section, and then the arm pin cylinder drives the arm pin to move to release the lock between the arm section and the previous arm section, and the arm section is extended and retracted to the target position with the telescopic cylinder; then the arm pin is driven by the arm pin cylinder to move, lock the arm section and the previous arm section to the target position, and then the cylinder pin cylinder drives the cylinder pin to move to release the lock between the telescopic cylinder and the arm section, and so on to realize the telescopic function.

[0003] At present, the single-bar latch models of automobile cranes on the market generally have obvious impact at the moment of retracting the arm, especially when the second and third arm sections are retracted in the fully extended state. The existing method for dealing with the impact problem is mainly to set the deceleration distance when the telescopic arm is started and when it is about to reach the target position, and reduce the operating speed when the action reaches the target position interval to reduce the impact phenomenon. However, this method, at the moment of retracting the arm, because the telescopic control valve is a switch valve, the valve is fully opened instantly when it is energized, and the system flow suddenly increases, making it difficult to control the movement speed of the cylinder. In addition, there is a large gap between the arm pin and the arm pin hole, causing the arm section to fall onto the arm pin due to gravity, causing an impact at the moment of retracting the arm. Summary of the invention

[0004] The invention provides a telescopic arm control method and system of a single-bar latch crane, which are used to solve the problem of arm section impact at the moment of opening the telescopic arm in the prior art.

[0005] The present invention provides a telescopic arm control method of a single-bar latch crane, comprising: Receiving a first control instruction for extending the arm; Calculate the target length of the telescopic arm; Control each boom section to decelerate and run to the corresponding target position, and when the current boom section runs to the corresponding target position, control the arm pin of the current boom section to be inserted into the arm pin hole of the corresponding outer arm section; The current arm section is controlled to retract until the arm pin contacts the lower end of the arm pin hole, thereby completing the arm extension action of the current arm section.

[0006] According to the telescopic arm control method of the horizontal bar latch crane provided by the present invention, the control of each arm section to decelerate and run to the corresponding target position includes: The distance from the currently moving boom section to the target position is obtained in real time. When the distance meets the preset distance, the currently moving boom section is controlled to decelerate and move to the corresponding target position.

[0007] According to the telescopic arm control method of the horizontal bar latch crane provided by the present invention, when the distance meets the preset distance, the current arm section is controlled to decelerate and run to the corresponding target position, comprising: When the distance meets the first preset distance, the current boom section is decelerated to a first level and continues to move toward the target position; When the distance meets the second preset distance, a secondary deceleration process is adopted for the current boom section until the current boom section runs to the target position.

[0008] The telescopic arm control method of the horizontal bar latch crane provided by the present invention also includes: receiving a second control instruction for retracting the arm; Control the arm section that needs to execute the instruction to extend forward, and release the connection between the arm pin of the arm section and the arm pin hole of the outer sleeve arm section after the extension; Controlling the current boom section to retract at a first speed until the current boom section runs to a set distance; The current boom section is controlled to operate normally at a second speed to complete a retracting start operation of the current boom section, wherein the second speed is greater than the first speed.

[0009] According to the telescopic arm control method of the single-bar latch crane provided by the present invention, the first speed is less than or equal to 5 m / s.

[0010] According to the telescopic arm control method of the single-bar latch crane provided by the present invention, each arm section is provided with four arm pin holes at intervals along its length direction.

[0011] In a second aspect, the present invention further provides a telescopic arm control system of a single-bar latch crane, comprising: a telescopic arm and a control unit, wherein the control unit is used to execute the telescopic arm control method of the single-bar latch crane as described in the first aspect.

[0012] The telescopic arm control system of the horizontal bar latch crane provided by the present invention also includes: A telescopic oil cylinder is arranged on the basic arm of the telescopic arm, and a cylinder pin is radially arranged on the driving rod of the telescopic oil cylinder, and the cylinder pin is used to cooperate with the cylinder pin socket at the tail of each section of the telescopic arm; An arm pin is arranged on the outer peripheral wall of the tail of each section of the telescopic arm, and the arm pin can be plugged and matched with the arm pin hole of the telescopic arm of the outer sleeve to fix two adjacent sections of the telescopic arm; The overflow valve is used to adjust the system oil pressure flowing through the telescopic arm and to buffer the impact between the arm pin and the arm pin hole at the moment when the telescopic arm starts to retract.

[0013] The telescopic arm control system of the single-bar latch crane provided according to the present invention also includes: a proportional main valve, which is connected to the telescopic cylinder and is used to control the flow of hydraulic oil in and out of the telescopic cylinder to control the extension or retraction speed of each section of the telescopic arm.

[0014] According to the telescopic arm control system of the single-bar latch crane provided by the present invention, the proportional main valve includes an extension arm proportional solenoid valve and a retraction arm proportional solenoid valve.

[0015] The present invention provides a telescopic boom control method and system for a single-bar latch crane. After the boom is extended to the desired position, the current boom section is retracted by a certain distance, so that the arm pin of the current boom section contacts the lower end of the arm pin hole, so that when the subsequent telescopic boom is recovered, the telescopic cylinder needs to push the current boom section forward to facilitate the disconnection of the arm pin from the arm pin hole. In this way, when the telescopic cylinder pushes the current boom section forward, the current boom section is provided with a bearing capacity, so that there is no impact sound when the boom is retracted. In addition, the telescopic cylinder is not subjected to pressure during hoisting, which plays a protective role on the telescopic cylinder. The pressure in the system is controlled by adding a relief valve, and the proportional control characteristics of the relief valve are used to accurately set the opening of the relief valve within the range of 0 to 100%. The relief valve can adjust its relief capacity as needed, so as to achieve accurate regulation of the system pressure, control the pressure fluctuation range in the system, make the system more stable, effectively reduce the pressure fluctuation at the moment of retracting the boom, avoid system vibration and noise caused by pressure fluctuation, effectively eliminate the jitter phenomenon at the moment of starting the retracting boom, and make the system run more smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The present invention is a flowchart of a telescopic arm control method of a single-bar latch crane provided in an embodiment of the present invention.

[0018] Figure 2It is a flow chart of a telescopic arm control method of a single-bar latch crane provided in another embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Combine the following Figure 1-Figure 2 The invention describes a telescopic arm control method and system of a horizontal bar latch crane.

[0021] The invention provides a telescopic arm control system of a single-bar latch crane, comprising a telescopic oil cylinder, an arm pin, a relief valve and a control unit.

[0022] Specifically, the telescopic cylinder is arranged on the basic arm of the telescopic arm, and the driving rod of the telescopic cylinder is radially provided with a cylinder pin, which is used to cooperate with the cylinder pin socket at the tail of each telescopic arm section; the arm pin is arranged on the outer peripheral wall at the tail of each telescopic arm section, and the arm pin can be plugged and matched with the arm pin hole of the telescopic arm of the outer sleeve to fix the two adjacent telescopic arms; the overflow valve adopts an electric proportional valve to adjust the system oil pressure flowing through the telescopic arm, and is used to buffer the impact between the arm pin and the arm pin hole at the moment of starting the retraction action of the telescopic arm.

[0023] It should be noted that the basic arm of the telescopic arm usually refers to the fixed part of the telescopic arm. As the starting part of the telescopic arm, it provides support for subsequent telescopic arm sections. The basic arm is a product in the prior art. Its structure and principle are not the focus of this article and will not be elaborated here.

[0024] The present invention controls the pressure in the system by adding a relief valve, and utilizes the proportional control characteristics of the relief valve to accurately set its opening within the range of 0-100%. For example, at 0% opening, the relief valve is completely closed, and the system pressure will continue to rise. Under this setting, the relief valve does not participate in pressure control. At 100% opening, the relief valve is fully opened, and the system pressure will quickly drop to the tank pressure or close to the tank pressure. At this time, the relief valve plays the greatest overflow role. At any opening between 0% and 100%, the relief valve can adjust its overflow capacity as needed, thereby realizing accurate regulation of the system pressure, controlling the pressure fluctuation range in the system, making the system more stable, and effectively reducing the fluctuation of the instantaneous pressure of the retracted arm, avoiding system vibration and noise caused by pressure fluctuations, and effectively eliminating the phenomenon of retracted arm shaking, so that the system runs more smoothly and smoothly. While maintaining a stable system pressure, the relief valve can also reduce unnecessary energy loss. When the system pressure is too high, excess hydraulic oil will flow back to the tank through the relief valve instead of continuing to circulate in the system and consume energy.

[0025] Furthermore, it also includes a proportional main valve, which is connected to the telescopic cylinder and is used to control the flow of hydraulic oil in and out of the telescopic cylinder to control the extension or retraction speed of each telescopic arm.

[0026] In this embodiment, the proportional main valve includes an arm extension proportional solenoid valve and an arm retracting proportional solenoid valve. The arm extension proportional solenoid valve is connected to the rod chamber of the telescopic cylinder, and can proportionally control the flow and pressure of the hydraulic oil, thereby achieving precise control of the arm extension action. The arm retracting proportional solenoid valve is connected to the rodless chamber of the telescopic cylinder, and can proportionally control the flow and pressure of the hydraulic oil, thereby achieving precise control of the arm retracting action.

[0027] In some embodiments, the overflow valve can be arranged in the oil circuit between the hydraulic pump and the telescopic cylinder. The pressure oil port of the overflow valve is directly connected to the output end of the hydraulic pump for receiving the pressure oil provided by the hydraulic pump. The return oil port of the overflow valve is connected to the oil tank, and the excess oil can be returned to the oil tank through the overflow valve. In addition, the overflow valve is also connected to the controller of the control unit, etc., so as to monitor and adjust the system pressure in real time.

[0028] This embodiment provides a telescopic arm control method of a horizontal bar latch crane, comprising: Step 101: Receive a first control instruction for extending the arm.

[0029] Optionally, the first control instruction may be obtained through one or more communication methods in the prior art, for example, a control instruction issued from a human-machine interaction interface with a soft switch on the crane; or a control instruction issued by a remote intelligent driving system.

[0030] Step 102: Calculate the target length of the telescopic arm, that is, the length of the telescopic arm when performing the telescopic action to the target. For example, the extended length of the telescopic arm is calculated according to the distance between the crane and the working target. According to the extended length of the telescopic arm, the control unit calculates the number of arm sections to be extended and the extended length of each arm section, so that the sum of the lengths of the arm sections is the target length of the telescopic arm.

[0031] Step 103: Control each boom section to decelerate and run to the corresponding target position, and when the current boom section runs to the corresponding target position, control the arm pin of the current boom section to be inserted into the arm pin hole of the corresponding outer arm section.

[0032] In this embodiment, the control unit controls the driving rod of the telescopic cylinder to drive the arm section to be moved to extend outward, and adjusts the opening of the arm extension proportional solenoid valve through the control unit. For example, the opening is adjusted to 80% of the normal action opening to reduce the oil pressure and oil volume entering the rod chamber of the telescopic cylinder, thereby realizing the telescopic cylinder driving the current arm section to decelerate. In this process, the overflow valve is in a fully open state.

[0033] Step 104: Control the current boom section to retract until the arm pin contacts the lower end of the arm pin hole, thereby completing the arm extension action of the current boom section.

[0034] In this embodiment, the opening of the relief valve is maintained, and the opening of the arm retraction proportional solenoid valve is reduced by the control unit, so that the arm pin of the current arm section moves to the lower end (minimum value) of the arm pin hole, and the arm retraction action is stopped.

[0035] With such an arrangement, after the arm is extended into place, the current arm section is retracted a certain distance so that the arm pin of the current arm section contacts the lower end of the arm pin hole. When the telescopic arm is subsequently recovered, the telescopic cylinder needs to push the current arm section forward to release the connection between the arm pin and the arm pin hole. In this way, when the telescopic cylinder pushes the current arm section forward, it will provide bearing capacity to the current arm section, so that there will be no impact sound when the arm is retracted. In addition, the telescopic cylinder will not be under pressure during hoisting, which has a protective effect on the telescopic cylinder.

[0036] It should be noted that the position of the arm pin hole on the telescopic arm of a crane is usually reserved large. After the arm pin is inserted into the hole, there will be a large reserved space above and below (generally 30 to 100 mm). The existence of the reserved space results in the specific position of the arm pin in the arm pin hole being uncertain after the arm is extended into place. By retracting the current arm section, the arm pin is made to abut against the lower end of the arm pin hole.

[0037] Furthermore, controlling each boom section to decelerate and run to the corresponding target position in step 103 includes: acquiring the distance from the currently moving boom section to the target position in real time, and when the distance meets the preset distance, controlling the current boom section to decelerate and run to the corresponding target position.

[0038] In this embodiment, the target position refers to when the arm pin of the current arm section moves to the target hole position (arm pin hole) of the outer arm section so that the elongation of the current arm section meets the elongation requirement. After reaching the target position, the arm pin of the arm section must be locked with the target hole position to prevent slipping.

[0039] Optionally, each arm section is provided with four arm pin holes at intervals along its length direction, which are respectively arranged at 0%, 46%, 92% and 100% of the total length of the arm section, wherein 0% indicates full retraction and 100% indicates full extension. The control unit calculates the length of each arm section, that is, the target hole position at which the arm pin of each arm section should be locked, according to the total length that the telescopic arm needs to be extended.

[0040] Furthermore, when the distance meets the first preset distance, the current boom section is subjected to a first-level deceleration process and continues to move toward the target position; when the distance meets the second preset distance, the current boom section is subjected to a second-level deceleration process until the current boom section reaches the target position.

[0041] In some embodiments, the first preset distance is 700m, the second preset distance is 300m, and the first deceleration is started at 700mm away from the target hole position, which can be achieved by adjusting the opening of the arm proportional solenoid valve to about 80% of the normal action opening, or by reducing the pump current when a pump control system is used. The overflow valve is fully open at this stage; the second deceleration is started when the distance to the target hole position is 300mm, which can be achieved by reducing the opening of the arm proportional solenoid valve to 50% of the normal action opening, or by closing the pump current output when a pump control system is used, and controlling the opening of the overflow valve at the same time to limit the operating speed of the telescopic cylinder, so that it slides to the target hole position at a speed not exceeding 10mm / s, inserting the arm pin, and then closing the arm proportional solenoid valve to stop the arm extension action.

[0042] In this embodiment, after the telescopic arm extension action is completed, the telescopic arm control method of the above-mentioned horizontal bar latch crane further includes: Step 201: receiving a second control instruction for retracting the arm. This step is the same as the above step 101, and the implementation process will not be repeated here.

[0043] Step 202: Control the arm segment that needs to execute the instruction currently to extend forward, and release the connection between the arm pin of the arm segment and the arm pin hole of the outer sleeve arm segment after the extension.

[0044] After the boom is extended into place, the arm pin of the front boom section contacts the lower end of the arm pin hole. Therefore, when performing the arm retracting action, the telescopic cylinder must first push the boom section forward to release the connection between the arm pin and the arm pin hole. In this way, when the telescopic cylinder pushes the boom section forward, it will provide bearing capacity to the boom section, so that there will be no impact sound when the arm is retracted. In addition, the telescopic cylinder will not be under pressure during lifting, which has a protective effect on the telescopic cylinder.

[0045] Step 203: Control the current boom section to retract at a first speed until the current boom section runs to a set distance; for example, the first speed is less than or equal to 5 m / s.

[0046] In this embodiment, when preparing to retract the arm, the opening of the overflow valve is adjusted to a smaller value, and the opening of the arm retraction proportional solenoid valve is adjusted to a smaller value at the same time, so that there will be no impact due to the gap between the arm pin and the arm pin hole at the moment of starting the arm retraction, and the current arm section will slowly run to the set distance at a speed not exceeding 5m / s.

[0047] Step 204: Control the current boom section to operate normally at a second speed to complete the retracted boom start operation of the current boom section, wherein the second speed is greater than the first speed.

[0048] With this setting, after the current boom section runs to the set distance, the opening of the boom retraction proportional solenoid valve is slowly increased to the normal value in a certain step length to complete the start-up operation of the boom retraction. The whole process will not produce impact and the vehicle body is stable.

[0049] The embodiment of the present invention provides a telescopic arm control system of a horizontal bar latch crane, comprising: A telescopic arm and a control unit, wherein the control unit is used to execute the telescopic arm control method of the horizontal bar latch crane.

[0050] Specifically, the control unit includes at least one processor; and at least one memory in communication with the processor, wherein: the memory stores program instructions executable by the processor, and the processor calls the program instructions to execute the above-mentioned container transport vehicle control method.

[0051] The control method of the present invention can be executed as a software program or computer instruction in a non-transient computer-readable storage medium or in a control system with a memory and a processor, and its calculation program is simple and runs fast. Each functional unit in each embodiment of the present invention can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of hardware plus software functional units. The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (processor) to perform some steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0052] The embodiment of the present invention also provides a crane, including the telescopic arm control system of the above-mentioned single-bar latch crane. The crane can be a single-cylinder latch model with a capacity of more than 80 tons. By adopting the telescopic arm control system of the above-mentioned single-bar latch crane, the impact problem of starting the retracted arm and extending the arm to the full position can be solved, and various advantages as described above can be obtained.

[0053] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or modes described in this specification and the features of the different embodiments or modes, without contradiction.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A telescopic arm control method for a horizontal bar latch crane, characterized in that: include: Receiving a first control instruction for extending the arm; Calculate the target length of the telescopic arm; Control each boom section to decelerate and run to the corresponding target position, and when the current boom section runs to the corresponding target position, control the arm pin of the current boom section to be inserted into the arm pin hole of the corresponding outer arm section; The current arm section is controlled to retract until the arm pin contacts the lower end of the arm pin hole, thereby completing the arm extension action of the current arm section.

2. The telescopic arm control method of the horizontal bar latch crane according to claim 1, characterized in that: The controlling each boom section to decelerate and move to the corresponding target position includes: The distance from the currently moving boom section to the target position is obtained in real time. When the distance meets the preset distance, the currently moving boom section is controlled to decelerate and move to the corresponding target position.

3. The telescopic arm control method of the horizontal bar latch crane according to claim 2, characterized in that: When the distance meets the preset distance, controlling the current boom section to decelerate and run to the corresponding target position includes: When the distance meets the first preset distance, the current boom section is decelerated to a first level and continues to move toward the target position; When the distance meets the second preset distance, a secondary deceleration process is adopted for the current boom section until the current boom section runs to the target position.

4. The telescopic arm control method of the horizontal bar latch crane according to claim 1 or 2, characterized in that: Also includes: receiving a second control instruction for retracting the arm; Control the arm section that needs to execute the instruction to extend forward, and release the connection between the arm pin of the arm section and the arm pin hole of the outer sleeve arm section after the extension; Controlling the current boom section to retract at a first speed until the current boom section runs to a set distance; The current boom section is controlled to operate normally at a second speed to complete a retracting start operation of the current boom section, wherein the second speed is greater than the first speed.

5. The telescopic arm control method of the horizontal bar latch crane according to claim 4, characterized in that: The first speed is less than or equal to 5 m / s.

6. The telescopic arm control method of the horizontal bar latch crane according to claim 1, characterized in that: Each arm section is provided with 4 arm pin holes at intervals along its length direction.

7. A telescopic arm control system for a horizontal bar latch crane, characterized in that: include: A telescopic arm and a control unit, wherein the control unit is used to execute the telescopic arm control method of a single-bar latch crane as described in any one of claims 1-6.

8. The telescopic arm control system of the horizontal bar latch crane according to claim 7, characterized in that: Also includes: A telescopic oil cylinder is arranged on the basic arm of the telescopic arm, and a cylinder pin is radially arranged on the driving rod of the telescopic oil cylinder, and the cylinder pin is used to cooperate with the cylinder pin socket at the tail of each section of the telescopic arm; An arm pin is arranged on the outer peripheral wall of the tail of each section of the telescopic arm, and the arm pin can be plugged and matched with the arm pin hole of the telescopic arm of the outer sleeve to fix two adjacent sections of the telescopic arm; The overflow valve is used to adjust the system oil pressure flowing through the telescopic arm and to buffer the impact between the arm pin and the arm pin hole at the moment when the telescopic arm starts to retract.

9. The telescopic arm control system of the horizontal bar latch crane according to claim 7, characterized in that: It also includes: a proportional main valve, which is connected to the telescopic cylinder and is used to control the flow of hydraulic oil in and out of the telescopic cylinder to control the extension or retraction speed of each section of the telescopic arm.

10. The telescopic arm control system of the horizontal bar latch crane according to claim 9, characterized in that: The proportional main valve comprises an arm extension proportional solenoid valve and an arm retraction proportional solenoid valve.

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