Carriage manual lock hook and carriage lifting oil cylinder linkage system and method and dumper

Abstract

The invention discloses a carriage manual lock hook and carriage lifting oil cylinder linkage system and method and a dumper. The system comprises a manual lock hook, a travel switch, an electromagnetic gas valve, a limiting gas valve, a lifting gas valve, a pneumatic control reversing valve and a lifting oil cylinder. The manual lock hook is connected with the travel switch and used for controlling opening and closing of the rear door and on-off of the travel switch; the travel switch is connected with the electromagnetic gas valve and used for controlling on-off of the electromagnetic gas valve; the electromagnetic gas valve is connected with the limiting gas valve and the lifting gas valve, the limiting gas valve is connected with the pneumatic control reversing valve, the pneumatic control reversing valve is connected with the lifting gas valve and the lifting oil cylinder, and the lifting gas valve is located in a cab of the dumper. The method comprises the steps that when the manual lock hook is closed, the travel switch is switched off, and the lifting oil cylinder cannot be lifted; and when the manual lock hook is opened, the travel switch is switched on, and the lifting oil cylinder is lifted. The device has the advantages that a driver can know the opening conditions of the manual lock hook and the rear door in time in a cab, a truck bed can be conveniently and better lifted, and the risk of turning over caused by misoperation is prevented.

Description

Technical Field

[0001] This invention relates to the field of dump truck technology, specifically to a manual locking hook and lifting cylinder linkage system, method, and dump truck. Background Technology

[0002] Currently, dump trucks typically unload by first opening the manual hooks and then raising the truck bed. However, due to the generally harsh working conditions, forgetting to open the manual hooks before raising the truck bed can prevent unloading and risk tipping over. To address this issue, the applicant has submitted this application, which prevents the truck bed from rising even if the manual hooks on both sides are forgotten before unloading, effectively avoiding the risk of tipping over. Summary of the Invention

[0003] The purpose of this invention is to provide a manual locking hook system and method for the truck body and a lifting cylinder for the truck body, as well as a dump truck, to solve the technical problems existing in the background art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] In the first aspect, a linkage system between a manual locking hook for a car body and a lifting cylinder for a car body is provided, including a manual locking hook, a limit switch, a solenoid valve, a limit valve, a lifting valve, a pneumatic directional valve, and a lifting cylinder.

[0006] The manual locking hook is connected to the limit switch and is used to control the opening and closing of the rear door of the dump truck and the on / off state of the limit switch;

[0007] The limit switch is connected to the solenoid valve and is used to control the on / off state of the solenoid valve.

[0008] The electromagnetic valve is connected to the limit valve and the lifting valve respectively, and is used to control the on / off state of the limit valve and the lifting valve.

[0009] The limit valve is connected to the pneumatically controlled directional valve and is used to control the switching of the pneumatically controlled directional valve.

[0010] The pneumatically controlled directional valve is connected to the lifting air valve and the lifting cylinder respectively, and is used to control the lifting cylinder to lift.

[0011] The lifting valve is installed in the cab of the dump truck.

[0012] Furthermore, the system also includes a hydraulic oil pump, a hydraulic oil tank, an air source, and a power source. The hydraulic oil pump is connected to the pneumatic directional valve and the hydraulic oil tank, respectively. The air source is connected to the lifting air valve, and the power source is connected to the limit switch.

[0013] Furthermore, there are two manual locking hooks and two limit switches, and the two manual locking hooks and two limit switches are respectively installed on the left and right sides of the rear column frame of the carriage;

[0014] Each manual locking hook has one end hinged to the rear column frame of the carriage, and the other end is used to engage with the stop pin set on the rear door of the carriage and the limit post set on the rear column frame of the carriage.

[0015] Each limit switch is paired with a manual locking hook on the same side to control the on / off state of the solenoid valve.

[0016] Furthermore, the two limit switches are connected in series, with one limit switch connected to the power supply and the other limit switch connected to the solenoid valve.

[0017] Furthermore, the solenoid valve, lifting cylinder, hydraulic pump, hydraulic tank, air source, and power supply are all installed on the chassis of the dump truck, the limit valve is installed on the lifting cylinder, and the pneumatic directional valve is installed on the hydraulic tank.

[0018] Secondly, a method for linking a manual locking hook for a freight car with a freight car lifting cylinder is provided, which is based on the manual locking hook and freight car lifting cylinder linkage system provided in the first aspect. The method includes:

[0019] When the manual locking hook is closed, the limit switch is in the open state, and the lifting circuit, air circuit, and hydraulic circuit of the cargo box are all blocked, so the lifting cylinder cannot lift.

[0020] When the manual locking hook is opened, the limit switch is in the ON state, and the lifting circuit, air circuit, and hydraulic circuit of the cargo box are all connected, and the lifting cylinder lifts.

[0021] The lifting circuit of the carriage consists of limit switches and a power supply; the lifting air circuit of the carriage consists of solenoid valves, limit valves, lifting valves and air sources; the lifting hydraulic circuit of the carriage consists of pneumatic control directional valves, lifting cylinders, hydraulic pumps and hydraulic tanks.

[0022] Furthermore, the method is as follows:

[0023] When the manual locking hook is closed, it presses down the limit switch, putting the limit switch in the open state. When the limit switch is open, the solenoid valve is not energized and does not work, so that the solenoid valve is not connected to the limit valve and the lifting valve. The limit valve is not connected to the pneumatic directional valve, and the pneumatic directional valve is in the neutral position. The lifting cylinder is not connected to the hydraulic pump. At this time, the lifting oil circuit of the truck bed is blocked, and the lifting cylinder cannot lift.

[0024] When the manual locking hook is opened, the limit switch is released, putting it in the ON state. When the limit switch is ON, the solenoid valve is energized, allowing air to pass between the solenoid valve and the limit valve and the lifting valve. The limit valve also passes air to the pneumatic directional valve, which switches to the lifting end. The lifting cylinder is then connected to the hydraulic pump, and the lifting oil circuit of the truck bed is open, causing the lifting cylinder to lift.

[0025] Thirdly, a dump truck is provided, including the manual locking hook and the lifting cylinder linkage system of the truck body provided in the first aspect.

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] (1) By setting the lifting valve of the car body in the cab, it is convenient for the driver to control the lifting of the car body by operating the lifting valve in the cab. At the same time, it is also convenient for the driver to know the status of the manual locking hook and the rear door of the car body in the cab. That is, when the car body can be lifted, it means that the manual locking hook and the rear door of the car body have been opened. When the car body cannot be lifted, it means that the manual locking hook and the rear door of the car body have not been opened. This can better lift the car body and prevent the risk of rollover caused by misoperation.

[0028] (2) By setting up a manual locking hook and a limit switch, when the manual locking hook is closed, the limit switch is disconnected, the solenoid valve is not connected, the lifting air valve is not ventilated, and the lifting cylinder cannot lift; when the manual locking hook is opened, the limit switch is connected, the solenoid valve and the lifting air valve are ventilated, and the lifting cylinder can lift. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this embodiment, the accompanying drawings used in the description of the embodiment will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the system principle of the manual locking hook and lifting cylinder linkage system of the carriage involved in the embodiment of the present invention when the lifting air valve is in the neutral position;

[0031] Figures 2-5 This is a schematic diagram of the system principle of the manual locking hook and lifting cylinder linkage system of the carriage involved in the embodiment of the present invention when the lifting air valve is in the right-side state;

[0032] Figure 6 This is a schematic diagram of the system principle of the manual locking hook and lifting cylinder linkage system of the carriage involved in the embodiment of the present invention when the lifting air valve is in the left position;

[0033] Figure 7 yes Figures 1-4Enlarged schematic diagram of a pneumatically controlled directional valve;

[0034] Figure 8 yes Figure 5 Enlarged schematic diagram of a pneumatically controlled directional valve;

[0035] Figure 9 yes Figure 6 Enlarged schematic diagram of a pneumatically controlled directional valve;

[0036] Figure 10 This is a partial schematic diagram of the linkage system between the manual locking hook and the lifting cylinder of the carriage, as described in an embodiment of the present invention, when the manual locking hook is closed.

[0037] Figure 11 This is a partial schematic diagram of the linkage system between the manual locking hook and the lifting cylinder of the carriage, as described in an embodiment of the present invention, when the manual locking hook is opened;

[0038] Explanation of reference numerals in the attached diagram: 1. Manual locking hook; 2. Limit switch; 3. Solenoid valve; 4. Limit valve; 5. Lifting valve; 6. Pneumatic directional valve; 7. Lifting cylinder; 8. Hydraulic pump; 9. Hydraulic oil tank; 10. Air source; 11. Power supply; 12. Oil filter; 13. Rear pillar frame of the cargo box; 14. Rear door of the cargo box; 15. Stop pin; 16. Limit post. Detailed Implementation

[0039] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following description, in conjunction with the accompanying drawings and specific embodiments, further explains how this invention is implemented.

[0040] Example 1: This example provides a linkage system between the manual locking hook of the carriage and the hydraulic cylinder for lifting the carriage. (See attached document.) Figures 1 to 6 The system includes a manual locking hook 1, a limit switch 2, a solenoid valve 3, a limit valve 4, a lifting valve 5, a pneumatic directional valve 6, and a lifting cylinder 7. The manual locking hook 1 is connected to the limit switch 2 to control the opening and closing of the dump truck's rear door 13 and the on / off state of the limit switch 2. The limit switch 2 is connected to the solenoid valve 3 to control its on / off state. The solenoid valve 3 is connected to both the limit valve 4 and the lifting valve 5 to control their respective states. The limit valve 4 is connected to the pneumatic directional valve 6 to control the switching of the pneumatic directional valve 6; the pneumatic directional valve 6 is connected to the lifting valve 5 and the lifting cylinder 7 respectively to control the lifting of the lifting cylinder 7; the lifting valve 5 is installed in the cab of the dump truck to allow the driver to control the lifting of the truck bed by operating the lifting valve 5 in the cab, and to allow the driver to know the switch status of the manual locking hook 1 in the cab, so as to better lift the truck bed and prevent the risk of rollover caused by misoperation.

[0041] Please continue reading. Figures 1 to 6The manual locking hook and lifting cylinder linkage system of the carriage also includes a hydraulic oil pump 8, a hydraulic oil tank 9, an air source 10, and a power supply 11. The hydraulic oil pump 8 is connected to the pneumatic reversing valve 6 and the hydraulic oil tank 9 to provide power to the carriage lifting oil circuit. The air source 10 is connected to the lifting air valve 5 to provide air to the carriage lifting air circuit. The power supply 11 is connected to the limit switch 2 to provide electrical energy to the carriage lifting circuit. Figures 1-9 The solid lines shown represent the car body lifting circuit; Figures 1-9 The dashed lines shown represent the air supply lines for lifting the carriage. Figures 1-9 The dotted lines shown represent the hydraulic lines for lifting the carriage.

[0042] Please continue reading. Figures 1 to 11 In some embodiments, there are two manual locking hooks 1 and two limit switches 2, and the two manual locking hooks 1 and the two limit switches 2 are respectively installed on the left and right sides of the rear pillar frame 13 of the carriage. Each manual locking hook 1 has one end hinged to the rear pillar frame 13 of the carriage, and the other end is used to engage with the stop pin 15 on the rear door 14 of the carriage and the limiting post 16 on the rear pillar frame 13 of the carriage for limiting. Each limit switch 2 cooperates with the manual locking hook 1 on the same side to control the on / off state of the solenoid valve 3. Specifically, the limit switch 2 is in the conducting state when in the free state; when the limit switch 2 is compressed, it is in the open state.

[0043] Please continue reading. Figures 1 to 6 In some embodiments, two limit switches 2 located on the left and right sides of the rear pillar frame 12 of the carriage are connected in series, with one limit switch 2 connected to the power supply 11 and the other limit switch 2 connected to the solenoid valve 3. The purpose of this arrangement is that the carriage cannot be lifted when either limit switch 2 is not turned on; the carriage can only be lifted when both limit switches 2 are turned on, thus avoiding the risk of overturning if the carriage is lifted with the rear door 14 closed.

[0044] Please continue reading. Figures 1 to 6 In some embodiments, an oil filter 12 is also provided between the return port T of the pneumatic directional valve 6 and the return port of the hydraulic oil tank 9.

[0045] Specifically, in some embodiments, the solenoid valve 3, lifting cylinder 7, hydraulic pump 8, hydraulic tank 9, air source 10, and power supply 11 are all installed on the chassis of the dump truck, the limit valve 4 is installed on the lifting cylinder 7, and the pneumatic directional valve 6 is installed on the hydraulic tank 9.

[0046] Specifically, in some embodiments, the lifting cylinder 7 is a front-mounted single-acting piston cylinder; the air source 10 is an air tank; and the power source 11 is the battery that comes with the dump truck.

[0047] Specifically, in some embodiments, the solenoid valve 3 is preferably a solenoid valve of model EQDF261; the limit valve 4 is preferably a limit valve of model XQF23; the lifting valve 5 is preferably a lifting valve of model MKQF34; and the pneumatic control directional valve 6 is preferably a speed-regulating pneumatic control directional valve of model 34TQF-F20L.

[0048] Specifically, the working principle of the manual locking hook and lifting cylinder linkage system for the carriage provided in Embodiment 1 is as follows:

[0049] See Figure 1 and Figure 7 When the driver turns the lifting air valve 5 to the neutral position in the cab, regardless of whether the limit switch 2 is turned on or off, the lifting air valve 5 is not connected to the solenoid air valve 3 and the pneumatic directional valve 6. The limit air valve 4 is not connected to the pneumatic directional valve 6. The pneumatic directional valve 6 is in the neutral position. The lifting cylinder 7 is not connected to the hydraulic pump 8, and the truck bed cannot be lifted.

[0050] See Figures 2 to 4 , Figure 7 When the driver turns the lifting air valve 5 to the right side in the cab, if both manual locking hooks 1 on the left and right sides are closed, or if any one of them is not closed, the two limit switches 2 connected in series on the left and right sides will not be connected. At this time, the solenoid air valve 3 will not be energized, the limit air valve 4 will not be connected to the lifting air valve 5 and the air-controlled reversing valve 6, the air-controlled reversing valve 6 will be in the neutral position, the lifting cylinder 7 will not be connected to the hydraulic pump 8, and the truck body cannot be lifted.

[0051] See Figure 5 and Figure 8 When the driver turns the lifting air valve 5 to the right side in the cab, if both manual locking hooks 1 on the left and right sides are opened, the two limit switches 2 connected in series on the left and right sides will be turned on. At this time, the solenoid air valve 3 will be energized and connected to the limit air valve 4 and the lifting air valve 5, so that the limit air valve 4 is connected to the lifting air valve 5 and the lifting end (i.e., the TIP end) of the pneumatic reversing valve 6 respectively. When the lifting end of the pneumatic reversing valve 6 is connected, the pneumatic reversing valve 6 will switch to the lifting end. At this time, the lifting cylinder 7 is connected to the hydraulic oil pump 8, and the truck body is lifted.

[0052] See Figure 6 and Figure 9 When the driver turns the lifting air valve 5 to the left side in the cab, the lifting air valve 5 is only connected to the lower end (i.e., the LOWER end) of the pneumatic reversing valve 6. At this time, the lifting cylinder 7 is connected to the return end of the hydraulic oil tank 9. At this time, the lowered state of the truck bed is not affected by whether the solenoid air valve 3 is connected or not, and is not affected by whether the rear door of the truck bed is open or not, or whether the manual lock hook 1 and the limit switch 2 are open or closed.

[0053] Example 2: This example provides a method for linking the manual locking hook of the carriage with the carriage lifting cylinder, specifically based on the linkage system of the manual locking hook and carriage lifting cylinder provided in Example 1. The method includes:

[0054] When the manual locking hook 1 is closed, the limit switch 2 is in the open state, the lifting circuit, the lifting air circuit, and the lifting oil circuit of the cargo box are all blocked, and the lifting cylinder 7 cannot lift.

[0055] When the manual locking hook 1 is opened, the limit switch 2 is in the on state, and the lifting circuit, lifting air circuit and lifting oil circuit of the car body are all connected, and the lifting cylinder 7 is lifted.

[0056] The lifting circuit of the carriage consists of a limit switch 2 and a power supply 11; the lifting air circuit of the carriage consists of a solenoid valve 3, a limit valve 4, a lifting air valve 5 and an air source 10; the lifting hydraulic circuit of the carriage consists of a pneumatic control directional valve 6, a lifting cylinder 7, a hydraulic pump 8 and a hydraulic oil tank 9.

[0057] Specifically, see Figures 1 to 11 In some specific embodiments, the method for linking the manual locking hook of the carriage with the carriage lifting cylinder is as follows:

[0058] When the manual locking hook 1 is closed, it presses down the limit switch 2, making the limit switch 2 in the open state. When the limit switch 2 is open, the solenoid valve 3 is not energized and does not work, so that the solenoid valve 3 is not connected to the limit valve 4 and the lifting valve 5. The limit valve 4 is not connected to the pneumatic control directional valve 6. The pneumatic control directional valve 6 is in the neutral position, and the lifting cylinder 7 is not connected to the hydraulic pump 8. At this time, the lifting oil circuit of the truck bed is blocked, and the lifting cylinder 7 cannot lift.

[0059] When the manual locking hook 1 is opened, the limit switch 2 is released, so that the limit switch 2 is in the on state. When the limit switch 2 is on, the solenoid valve 3 is energized and works, so that the solenoid valve 3 is connected to the limit valve 4 and the lifting valve 5. The limit valve 4 is connected to the pneumatic control directional valve 6. The pneumatic control directional valve 6 is switched to the lifting end, and the lifting cylinder 7 is connected to the hydraulic pump 8. At this time, the lifting oil circuit of the truck bed is connected, and the lifting cylinder 7 lifts.

[0060] More specifically, in the above method embodiment, when the limit switch 2 is open, the lifting circuit of the carriage is not connected and cannot be energized to the solenoid valve 3; when the solenoid valve 3 is not energized, the solenoid valve 3 cannot allow the limit valve 4 and the lifting valve 5 to pass through, and at this time the lifting air circuit of the carriage cannot be connected; when the limit valve 4 is not energized, it cannot energize the lifting end (i.e., the TIP end) of the pneumatic reversing valve 6, and the pneumatic reversing valve 6 cannot connect the lifting cylinder 7 and the hydraulic pump 8, and at this time the lifting oil circuit of the carriage cannot be connected, and the lifting cylinder 7 cannot lift the carriage.

[0061] When limit switch 2 is turned on, the lifting circuit of the truck bed is connected, which can energize the solenoid valve 3. When the solenoid valve 3 is energized, it can vent the limit valve 4 and the lifting valve 5, thus opening the lifting air circuit of the truck bed. When the limit valve 4 is vented, it can vent the lifting end (i.e., the TIP end) of the pneumatic directional valve 6, which can then connect the lifting cylinder 7 and the hydraulic pump 8, thus opening the lifting oil circuit of the truck bed and enabling the lifting cylinder 7 to lift the truck bed.

[0062] Example 3: This example provides a dump truck, including the manual locking hook and lifting cylinder linkage system of the truck body described in Example 1.

[0063] In summary, the technical solutions provided by this invention have the following advantages compared with the prior art:

[0064] (1) By setting the lifting valve 5 in the cab, it is convenient for the driver to control the lifting of the truck bed by operating the lifting valve 5 in the cab. At the same time, it is also convenient for the driver to know the opening status of the manual locking hook 1 and the rear door 14 of the truck bed in the cab. That is, when the truck bed can be lifted, it means that the manual locking hook 1 and the rear door 14 of the truck bed have been opened. When the truck bed cannot be lifted, it means that the manual locking hook 1 and the rear door 14 of the truck bed have not been opened. This can better lift the truck bed and prevent the risk of rollover caused by misoperation.

[0065] (2) By setting up a manual locking hook and a limit switch, when the manual locking hook is closed, the limit switch is disconnected, the solenoid valve is not connected, the lifting air valve is not ventilated, and the lifting cylinder cannot lift; when the manual locking hook is opened, the limit switch is connected, the solenoid valve and the lifting air valve are ventilated, and the lifting cylinder can lift.

[0066] Finally, it should be noted that the above description is only an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A linkage system between a manual locking hook for a freight car and a hydraulic cylinder for lifting the freight car, characterized in that: Includes manual locking hook (1), limit switch (2), solenoid valve (3), limit valve (4), lifting valve (5), pneumatic directional valve (6) and lifting cylinder (7); The manual locking hook (1) is connected to the limit switch (2) and is used to control the opening and closing of the rear door (13) of the dump truck and the on / off state of the limit switch (2); The limit switch (2) is connected to the solenoid valve (3) and is used to control the opening and closing of the solenoid valve (3); The electromagnetic valve (3) is connected to the limit valve (4) and the lifting valve (5) respectively, and is used to control the opening and closing of the limit valve (4) and the lifting valve (5); The limiting air valve (4) is connected to the pneumatic reversing valve (6) and is used to control the reversing of the pneumatic reversing valve (6); The pneumatic reversing valve (6) is connected to the lifting air valve (5) and the lifting cylinder (7) respectively, and is used to control the lifting cylinder (7) to lift; The lifting valve (5) is installed in the cab of the dump truck.

2. The manual locking hook and lifting cylinder linkage system for the car body according to claim 1, characterized in that: It also includes a hydraulic oil pump (8), a hydraulic oil tank (9), an air source (10), and a power supply (11). The hydraulic oil pump (8) is connected to the pneumatic directional valve (6) and the hydraulic oil tank (9) respectively. The air source (10) is connected to the lifting air valve (5). The power supply (11) is connected to the limit switch (2).

3. The manual locking hook and lifting cylinder linkage system for the car body according to claim 2, characterized in that: The number of manual locking hooks (1) and limit switches (2) are both two, and the two manual locking hooks (1) and the two limit switches (2) are respectively installed on the left and right sides of the rear column frame (12) of the carriage; Among them, one end of each manual lock hook (1) is hinged to the rear column frame (12) of the carriage, and the other end is used to hook and cooperate with the stop pin (14) set on the rear door (13) of the carriage and the limit post (15) set on the rear column frame (12) of the carriage for limiting cooperation; Each limit switch (2) is paired with a manual locking hook (1) on the same side to control the opening and closing of the solenoid valve (3).

4. The manual locking hook and lifting cylinder linkage system for the car body according to claim 3, characterized in that: The two limit switches (2) are connected in series, and one of the limit switches (2) is connected to the power supply (11), while the other limit switch (2) is connected to the solenoid valve (3).

5. The manual locking hook and lifting cylinder linkage system for the car body according to claim 2, characterized in that: The electromagnetic valve (3), lifting cylinder (7), hydraulic pump (8), hydraulic tank (9), air source (10) and power supply (11) are all installed on the chassis of the dump truck. The limit valve (4) is installed on the lifting cylinder (7), and the pneumatic reversing valve (6) is installed on the hydraulic tank (9).

6. A method for linking a manual locking hook for a freight car with a freight car lifting cylinder, characterized in that: The method is based on the manual locking hook and lifting cylinder linkage system of the car body as described in any one of claims 1-5, and the method includes: When the manual locking hook (1) is closed, the limit switch (2) is in the open state, the lifting circuit of the car body, the air circuit of the car body and the oil circuit of the car body are all blocked, and the lifting cylinder (7) cannot lift; When the manual locking hook (1) is opened, the limit switch (2) is in the on state, the lifting circuit of the car body, the air circuit of the car body and the oil circuit of the car body are all connected, and the lifting cylinder (7) lifts; The lifting circuit of the carriage consists of a limit switch (2) and a power supply (11); the lifting air circuit of the carriage consists of an electromagnetic air valve (3), a limit air valve (4), a lifting air valve (5) and an air source (10); the lifting oil circuit of the carriage consists of a pneumatic control reversing valve (6), a lifting oil cylinder (7), a hydraulic oil pump (8) and a hydraulic oil tank (9).

7. The method for linking the manual locking hook of the carriage with the carriage lifting cylinder according to claim 6, characterized in that: The method is as follows: When the manual locking hook (1) is closed, it presses the limit switch (2), so that the limit switch (2) is in the open state. When the limit switch (2) is open, the solenoid valve (3) is not energized and does not work, so that the solenoid valve (3) is not connected to the limit valve (4) and the lifting valve (5), the limit valve (4) is not connected to the pneumatic reversing valve (6), the pneumatic reversing valve (6) is in the neutral position, the lifting cylinder (7) is not connected to the hydraulic pump (8), at this time the lifting oil circuit of the carriage is not open, and the lifting cylinder (7) cannot lift; When the manual locking hook (1) is opened, the limit switch (2) is released, so that the limit switch (2) is in the on state. When the limit switch (2) is on, the solenoid valve (3) is energized and works, so that the solenoid valve (3) is connected to the limit valve (4) and the lifting valve (5). The limit valve (4) is connected to the pneumatic control directional valve (6). The pneumatic control directional valve (6) is switched to the lifting end, and the lifting cylinder (7) is connected to the hydraulic pump (8). At this time, the lifting oil circuit of the carriage is connected, and the lifting cylinder (7) is lifted.

8. A dump truck, characterized in that: The system includes the manual locking hook and lifting cylinder linkage system for the car body as described in any one of claims 1-5.

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