Hydraulic system and method for simultaneous lifting of an aircraft

Abstract

The application discloses a hydraulic system for synchronous jacking of an airplane, characterized in that the hydraulic system is formed by combining an electric control system and a manual control system, wherein the manual control system is an auxiliary control system and assists the electric control system in operation; wherein the hydraulic system is composed of two main connection lines of a hydraulic accumulator, a driving device, a manual pump unit, an adjusting control unit and a jack control unit respectively. Through application in automatic synchronous jacking of main jacks, the hydraulic system reaches a stable technical state, has good sealing performance, high efficiency, low noise and low power consumption, and realizes full-airplane jacking of various airplanes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aircraft hydraulic system analysis, and more particularly relates to an aircraft synchronous jacking hydraulic system and a method thereof. BACKGROUND

[0002] With the development of society, there are cases of using synchronous cylinders to achieve synchronous control of oil cylinders at home and abroad. By controlling the consistent flow into each oil cylinder, the similar hydraulic travel of each oil cylinder is achieved, thereby achieving synchronous control of the oil cylinders, and the synchronization accuracy is close to 1%. However, this scheme has certain defects. First, the axial and radial dimensions of the synchronous cylinder are large, which is not convenient for arrangement. Second, this scheme is an open-loop design, which is not conducive to eliminating the cumulative error of each oil cylinder. Third, when the size difference of each oil cylinder is large, a non-standard synchronous cylinder needs to be made, which reduces the synchronization accuracy, increases the design difficulty, and greatly increases the research and development cost.

[0003] Moreover, there are also cases of using synchronous motors to achieve synchronous control of oil cylinders at home and abroad. By controlling the consistent flow into each oil cylinder, the similar hydraulic travel of each oil cylinder is achieved, thereby achieving synchronous control of the oil cylinders, and the synchronization accuracy is close to 1%. The defects are that first, this scheme is an open-loop design, which is not conducive to eliminating the cumulative error of each oil cylinder. Second, when the size difference of each oil cylinder is large, a non-standard synchronous motor needs to be made, which reduces the synchronization accuracy, increases the design difficulty, and increases the research and development cost.

[0004] All types of aircraft at home and abroad use hand pumps to achieve full aircraft jacking through hydraulic cylinders. The use of hand pumps greatly increases the labor intensity of maintenance personnel. On the other hand, it is also impossible to achieve full aircraft synchronous jacking, which causes the aircraft to tilt and bear internal stress. At the same time, through the operation of hand pumps by maintenance personnel to achieve full aircraft jacking, the efficiency of aircraft maintenance support is greatly reduced. With the vigorous development of China's aviation industry, it is unrealistic for maintenance personnel to achieve the jacking of large-tonnage aircraft through hand pumps. Therefore, it is urgent to develop an automatic synchronous jacking main jack. As a key link in the research, the hydraulic system will directly determine whether the automatic synchronous jacking main jack is feasible.

[0005] Therefore, it is necessary to propose a new scheme that can solve the above series of defects. SUMMARY

[0006] In order to obtain an efficient and energy-saving hydraulic system that can achieve automatic synchronous jacking function, the following technical scheme is adopted:

[0007] The hydraulic system for the aircraft synchronous jacking is formed by the combination of the electric control system and the manual control system, wherein the manual control system is the auxiliary control system, and the auxiliary electric control system operates;

[0008] The hydraulic system is composed of the hydraulic accumulator, the driving device, the manual pump unit, the regulating control unit and the jack control unit, and two main connection lines.

[0009] The first main connection line is connected from the hydraulic accumulator to the driving device, the output of the driving device is connected to the input of the regulating control unit, the regulating control unit is connected in parallel with the jack control unit, and the output of the regulating control unit is connected to the hydraulic accumulator to form the first main connection line.

[0010] The second main connection line is connected from the hydraulic accumulator to the manual pump unit, the manual pump unit is connected to the input of the regulating control unit, the regulating control unit is connected in parallel with the jack control unit, and the output of the regulating control unit is connected to the hydraulic accumulator to form the second main connection line.

[0011] Further solutions are,

[0012] The hydraulic accumulator is composed of the oil tank 1, the oil suction filter 2, the oil discharge nozzle and plug 3, the air filter 4 and the hydraulic gauge 5, wherein the air filter 4, the hydraulic gauge 5 and the oil discharge nozzle and plug 3 are respectively connected and arranged outside the oil tank 1, and the oil suction filter 2 is arranged inside the oil tank 1.

[0013] Further solutions are,

[0014] The driving device is composed of the motor 6 and the internal gear pump 7.

[0015] Further solutions are,

[0016] The manual pump unit is composed of the one-way valve and hand pump 8.1 and the one-way valve and hand pump 8.2 connected in parallel.

[0017] Further solutions are,

[0018] The jack control unit is composed of the pressure sensor 20 and the main jack actuator 21.

[0019] Further solutions are,

[0020] The adjusting control unit is connected by the first one-way valve 9.1, the second one-way valve 9.2, the third one-way valve 9.3, the fine filter 10, the pressure gauge 11, the overflow valve 12, the first two-position two-way electromagnetic reversing valve 13.1, the second two-position two-way electromagnetic reversing valve 13.2, the proportional valve 14, the stop valve 15, the pressure compensator 16, the manual three-position four-way reversing valve 17, the shuttle valve 18 and the constant difference pressure reducing valve 19;

[0021] The first one-way valve 9.1 is connected with the driving device at the first end and connected with the fine filter 10 at the second end and the overflow valve 12 at the first end; the fine filter 10 is connected with the first two-position two-way electromagnetic reversing valve 13.1 at the first end and the manual three-position four-way reversing valve 17 at the first end at the second end, and the pressure gauge 11 is further arranged on the pipeline connected with the fine filter 10 at the second end and the manual three-position four-way reversing valve 17 at the first end; the second end of the first two-position two-way electromagnetic reversing valve 13.1 is connected with the first end of the proportional valve 14; the second end of the proportional valve 14 is connected with the first end of the constant difference pressure reducing valve 19; the second end of the constant difference pressure reducing valve 19 is connected with the first end of the second two-position two-way electromagnetic reversing valve 13.2; the second end of the second two-position two-way electromagnetic reversing valve 13.2 is connected with the first end of the main jack cylinder 20 and the third end of the manual three-position four-way reversing valve 17;

[0022] The first end of the second one-way valve 9.2 is connected with the manual pump unit, and the second end is connected with the second end of the first one-way valve 9.1 and the first end of the overflow valve 12; the second end of the overflow valve 12 is connected with the first end of the third one-way valve 9.3, the first end of the manual three-position four-way reversing valve 17 and the fourth end of the proportional valve 14;

[0023] The second end of the third one-way valve 9.3 is connected with the third end of the proportional valve 14, the second end of the main jack cylinder 20 and the second end of the manual three-position four-way reversing valve 17;

[0024] The fourth end of the proportional valve 14 is connected with the fourth end of the manual three-position four-way reversing valve 17 and the hydraulic accumulator;

[0025] The pipeline connected with the fourth end of the proportional valve 14 and the fourth end of the manual three-position four-way reversing valve 17 is further provided with the pressure compensator 16;

[0026] The shuttle valve 18 is further arranged between the second end and the third end of the proportional valve 14.

[0027] Further schemes are,

[0028] A method for realizing an aircraft synchronous jacking hydraulic system, specifically comprising the following steps:

[0029] A. When the electric pump in the electric control system is used as the power element, the cut-off valve 15 is first locked, the hand-operated three-position four-way reversing valve 17 is in the middle position, and when the system detects the signal of the main jack cylinder 21 rising or falling, the electromagnetic reversing valve 13.1 and 13.2 are immediately opened.

[0030] B. When the hand pump in the manual control system is used as the power element, during the rising process of the main jack cylinder 21, before rising, the cut-off valve 15 should be fully opened, the hand-operated three-position four-way reversing valve 17 is pulled to the rising position, and the hand pumps 8.1 and 8.2 are operated; during the falling process of the main jack cylinder 21, before falling, the cut-off valve 15 should be fully locked, then the hand-operated three-position four-way reversing valve 17 is in the falling position, and the cut-off valve 15 is slowly opened. Advantages

[0031] 1) The traditional idea of realizing aircraft jacking through a hand pump is abandoned, and a new scheme of automatic synchronous jacking is introduced into the aircraft jacking hydraulic system.

[0032] 2) By introducing the automatic synchronous hydraulic system into the aircraft jacking hydraulic system, the electric pump replaces the long-term used hand pump, reduces the labor intensity of the maintenance personnel, and greatly improves the efficiency of aircraft maintenance support.

[0033] 3) After introducing the automatic synchronous jacking hydraulic system into the aircraft jacking, the synchronization accuracy of the aircraft synchronous jacking is maintained within 3mm, and the phenomenon of aircraft tilting and bearing internal stress is effectively avoided.

[0034] 4) In the present application, the motor drives the internal gear pump to provide power source for the hydraulic system, and the hydraulic system can adjust the motor speed as needed to adjust the hydraulic system flow, effectively avoiding the heating caused by the overflow of redundant oil through the overflow valve.

[0035] 5) In the present application, the load-sensitive valve makes the unloading pressure be adjusted in real time according to the required pressure of the actuator (the unloading pressure is 1.2MPa greater than the required pressure of the actuator), thereby avoiding the heating caused by the overflow of the safety overflow valve at a higher pressure; on the other hand, the load-sensitive valve effectively ensures that the pressure difference between the P port and the A port of the servo valve is stable at 1.2MPa, so that the flow through the servo valve is proportional to the opening, improving the stability of the hydraulic system adjustment and eliminating the phenomenon of actuator movement.

[0036] 6) The application is applied to the automatic synchronous jacking main jack, and has the advantages of stable technical state, good sealing performance, high efficiency, low noise and low power consumption, and realizes the jacking of all types of airplanes. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The system diagram of the hydraulic system for the synchronous jacking of the airplane

[0038] 1. oil tank; 2. oil suction filter; 3. oil drain nozzle and plug; 4. air filter; 5. hydraulic gauge; 6. motor; 7. internal gear pump; 8. hand pump; 9. check valve; 10. fine filter; 11. pressure gauge; 12. overflow valve; 13. two-position two-way electromagnetic reversing valve; 14. proportional valve; 15. stop valve; 16. pressure compensator; 17. hand-operated three-position four-way reversing valve; 18. shuttle valve; 19. constant-difference pressure reducing valve; and 20. main jack operating cylinder. DETAILED DESCRIPTION

[0039] In order to make the above objectives, characteristics and advantages of the present application more apparent, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the concept of the present application, and therefore the present application is not limited to the specific embodiments disclosed below. EMBODIMENT

[0040] The hydraulic system for the synchronous jacking of an airplane is formed by the combination of an electric control system and a manual control system, wherein the manual control system is an auxiliary control system and the auxiliary electric control system is operated; the hydraulic system is composed of a hydraulic accumulator, a driving device, a hand pump unit, a regulating control unit and a jack control unit to form two main flow connection lines;

[0041] The first main flow connection line is a connection line for completing the operation of the system through electric control operation, and is connected from the hydraulic accumulator to the driving device, the output of the driving device is connected to the input of the regulating control unit, the regulating control unit and the jack control unit are connected in parallel, and the output of the regulating control unit is connected to the hydraulic accumulator to form the first main flow connection line;

[0042] The second main flow connection line is a connection line for completing the operation of the system through the operation of the hand pump, and is connected from the hydraulic accumulator to the hand pump unit, the hand pump unit is connected to the input of the regulating control unit, the regulating control unit and the jack control unit are connected in parallel, and the output of the regulating control unit is connected to the hydraulic accumulator to form the second main flow connection line.

[0043] The new scheme of automatic synchronization jacking is introduced into the hydraulic system of the aircraft jacking, which reduces the labor intensity of the maintenance personnel, greatly improves the efficiency of the aircraft maintenance and support, and avoids the inclination and internal stress of the aircraft. Embodiment

[0044] The hydraulic accumulator is composed of an oil tank 1, an oil suction filter 2, a drain nozzle and plug 3, an air filter 4 and a hydraulic gauge 5.

[0045] The air filter 4, the hydraulic gauge 5 and the drain nozzle and plug 3 are respectively connected to the outside of the oil tank 1, and the oil suction filter 2 is arranged in the inside of the oil tank 1.

[0046] The driving device is composed of a motor 6 and an internal gear pump 7.

[0047] The manual pump unit is composed of a first one-way valve and a hand pump 8.1, and a second one-way valve and a hand pump 8.2.

[0048] The jack control unit is composed of a pressure sensor 20 and a main jack actuator cylinder 21.

[0049] The adjustment control unit is composed of a first one-way valve 9.1, a second one-way valve 9.2, a third one-way valve 9.3, a fine filter 10, a pressure gauge 11, an overflow valve 12, a first two-position two-way electromagnetic directional valve 13.1, a second two-position two-way electromagnetic directional valve 13.2, a proportional valve 14, a stop valve 15, a pressure compensator 16, a manual three-position four-way directional valve 17, a shuttle valve 18 and a constant difference pressure reducing valve 19.

[0050] The first end of the first one-way valve 9.1 is connected to the driving device, the second end is connected to the first end of the fine filter 10 and the first end of the overflow valve 12; the second end of the fine filter 10 is connected to the first end of the first two-position two-way electromagnetic directional valve 13.1 and the first end of the manual three-position four-way directional valve 17, and the pressure gauge 11 is arranged on the pipeline connected to the second end of the fine filter 10 and the first end of the manual three-position four-way directional valve 17; the second end of the first two-position two-way electromagnetic directional valve 13.1 is connected to the first end of the proportional valve 14; the second end of the proportional valve 14 is connected to the first end of the constant difference pressure reducing valve 19; the second end of the constant difference pressure reducing valve 19 is connected to the first end of the second two-position two-way electromagnetic directional valve 13.2; the second end of the second two-position two-way electromagnetic directional valve 13.2 is connected to the first end of the main jack actuator cylinder 20 and the third end of the manual three-position four-way directional valve 17.

[0051] The first end of the second one-way valve 9.2 is connected with the manual pump unit, the second end of the second one-way valve 9.2 is connected with the first end of the first one-way valve 9.1, the first end of the overflow valve 12, the second end of the overflow valve 12 is connected with the first end of the third one-way valve 9.3, the first end of the manual three-position four-way directional valve 17, the fourth end of the proportional valve 14;

[0052] The second end of the third one-way valve 9.3 is connected with the third end of the proportional valve 14, the second end of the main jack operating cylinder 20, the second end of the manual three-position four-way directional valve 17;

[0053] The fourth end of the proportional valve 14 is connected with the fourth end of the manual three-position four-way directional valve 17, the hydraulic accumulator;

[0054] A pressure compensator 16 is further arranged on the pipeline connected with the fourth end of the proportional valve 14 and the fourth end of the manual three-position four-way directional valve 17;

[0055] A shuttle valve 18 is further arranged between the second end and the third end of the proportional valve 14.

[0056] The system is a two-power driving system, which realizes its functions through two operation methods:

[0057] (1) When the electric pump is used as a power element, the specific operation steps are as follows: first, the stop valve 15 is in a locked state, and the manual three-position four-way directional valve 17 is in a middle position. When the system detects the signal of the main jack operating cylinder 21 rising or falling, the electromagnetic directional valves 13.1 and 13.2 are immediately opened.

[0058] a) Main jack operating cylinder 21 rising process. The motor 6 drives the internal gear pump 7 to act, so that the hydraulic oil passes through the oil suction filter 2, the one-way valve 9.1, the fine filter 10, the electromagnetic directional valve 13.1, the proportional valve 14 (located in the rising position), the constant differential pressure reducing valve 19, the electromagnetic directional valve 13.2, and then enters the lower cavity of the main jack operating cylinder 21, so that the main jack operating cylinder 21 realizes rising under the action of the pressure oil. The oil in the upper cavity of the main jack operating cylinder 21 flows back to the oil tank through the proportional valve 14;

[0059] b) Main jack operating cylinder 21 falling process. First, the system detects whether the lower cavity pressure is greater than 1.5 MPa (slightly greater than the critical pressure at which the main jack operating cylinder 21 can automatically fall);

[0060] c) When the lower chamber pressure is greater than 1.5 MPa, the proportional valve 14 is in the descending position, and the main jack cylinder 21 is driven by the weight of the aircraft, so that the oil in the lower chamber flows back to the oil tank 1 through the proportional valve 12. Because the upper chamber of the main jack cylinder 21 tends to form a negative pressure, part of the oil in the low-pressure oil circuit flows to the upper chamber of the main jack cylinder 21 through the one-way valve 9.3, so as to realize the oil supplement of the upper chamber and avoid the formation of cavitation and pitting phenomenon;

[0061] d) When the lower chamber pressure is less than 1.5 MPa, the motor 6 drives the internal gear pump 7 to operate, so that the pressure oil enters the upper chamber of the main jack cylinder 21 through the oil suction filter 2, the one-way valve 9.1, the fine filter 10, the electromagnetic reversing valve 13.1, the proportional valve 14 (in the ascending position), the constant-difference pressure reducing valve 19 and the electromagnetic reversing valve 13.2, and under the action of the pressure oil, the main jack cylinder 21 is forced to descend. The pressure oil in the lower chamber flows back to the oil tank 1 through the electromagnetic reversing valve 13.2, the constant-difference pressure reducing valve 19 and the proportional valve 12.

[0062] 2) When the hand pump is used as a power element, the operation process is as follows:

[0063] a) The ascending process of the main jack cylinder 21. Before ascending, the shut-off valve 15 should be completely opened, and the hand-operated three-position four-way reversing valve 17 is pulled to the ascending position. The hand pumps 8.1 and 8.2 are operated, so that the hydraulic oil enters the lower chamber of the main jack cylinder 21 through the oil suction filter 2, the one-way valve 9.2, the fine filter 10 and the hand-operated three-position four-way reversing valve 17, and under the action of the pressure oil, the main jack cylinder 21 is realized to ascend. The oil in the upper chamber of the main jack cylinder 21 flows back to the oil tank 1 through the hand-operated three-position four-way reversing valve 17;

[0064] b) The descending process of the main jack cylinder 21. The main jack cylinder 21 is forced to form a positive pressure in the lower chamber under the action of the gravity of the aircraft, and the upper chamber tends to form a negative pressure. Before descending, the shut-off valve 15 should be completely locked, and then the hand-operated three-position four-way reversing valve 17 is located in the descending position, and then the shut-off valve 15 is slowly opened. The oil in the lower chamber flows back to the oil tank 1 through the shut-off valve 15 and the hand-operated three-position four-way reversing valve 17. Because the upper chamber of the main jack cylinder 21 tends to form a negative pressure, part of the oil in the low-pressure oil circuit flows to the upper chamber of the main jack cylinder 21 through the one-way valve 9.3, so as to realize the oil supplement of the upper chamber and avoid the formation of cavitation and pitting phenomenon.

[0065] The method adopts the form of motor driving internal gear pump to provide power source for the hydraulic system, can adjust the motor rotating speed to adjust the hydraulic system flow according to the requirement, avoids the heat generated by the overflow of redundant oil through the overflow valve; the load sensitive valve makes the unloading pressure be adjusted in real time according to the required pressure of the actuator, avoids the heat generated by the overflow of the safety overflow valve at higher pressure, the load sensitive valve also effectively ensures that the pressure difference between the P port and the A port of the servo valve is stable at 1.2 MPa, makes the flow through the servo valve be adjusted in direct proportion to the opening, improves the system stability, eliminates the hunting phenomenon.

[0066] Although the present application has been described with reference to some embodiments above, various modifications can be made thereto and equivalents thereof employed without departing from the scope of the application, and in particular, features of the various embodiments of the application described herein can be combined with each other unless technically incompatible, and the description of the combinations of these features is not exhaustively described herein only for the consideration of omitting the length and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes the claims.

Claims

1. A hydraulic system for synchronizing lifting of an aircraft, characterized in that, The hydraulic system is formed by the combination of the electric control system and the manual control system, wherein the manual control system is an auxiliary control system assisting the electric control system to operate; The hydraulic system is composed of two main flow connection lines, namely a hydraulic accumulator, a driving device, a manual pump unit, a regulating control unit and a jack control unit; The first main flow connection line is connected from the hydraulic accumulator to the driving device, the output of the driving device is connected to the input of the regulating control unit, the regulating control unit is connected in parallel with the jack control unit, and the output of the regulating control unit is connected to the hydraulic accumulator to form the first main flow connection line; The second main flow connection line is connected from the hydraulic accumulator to the manual pump unit, the manual pump unit is connected to the input of the regulating control unit, the regulating control unit is connected in parallel with the jack control unit, and the output of the regulating control unit is connected to the hydraulic accumulator to form the second main flow connection line; The hydraulic accumulator is composed of an oil tank (1), an oil suction filter (2), a drain nozzle and a plug (3), an air filter (4) and a hydraulic gauge (5), wherein the air filter (4), the hydraulic gauge (5) and the drain nozzle and the plug (3) are respectively connected and arranged outside the oil tank (1), and the oil suction filter (2) is arranged inside the oil tank (1); The driving device is composed of a motor (6) and an internal gear pump (7) connected for driving; The manual pump unit is composed of a fourth one-way valve and a first hand pump (8.1), a fifth one-way valve and a second hand pump (8.2) connected in parallel; The regulating control unit is composed of a first one-way valve (9.1), a second one-way valve (9.2), a third one-way valve (9.3), a fine filter (10), a pressure gauge (11), an overflow valve (12), a first two-position two-way electromagnetic reversing valve (13.1), a second two-position two-way electromagnetic reversing valve (13.2), a proportional valve (14), a stop valve (15), a pressure compensator (16), a manual three-position four-way reversing valve (17), a shuttle valve (18) and a constant difference pressure reducing valve (19) connected together; The jack control unit is composed of a pressure sensor (20) and a main jack operating cylinder (21) connected together.

2. Hydraulic system for the simultaneous lifting of an aircraft according to claim 1, characterized in that The regulating control unit is composed of a first one-way valve (9.1), a second one-way valve (9.2), a third one-way valve (9.3), a fine filter (10), a pressure gauge (11), an overflow valve (12), a first two-position two-way electromagnetic reversing valve (13.1), a second two-position two-way electromagnetic reversing valve (13.2), a proportional valve (14), a stop valve (15), a pressure compensator (16), a manual three-position four-way reversing valve (17), a shuttle valve (18) and a constant difference pressure reducing valve (19) connected together; The first one-way valve (9.1) is connected with the driving device at the first end, and is connected with the fine filter (10) at the second end, and is connected with the overflow valve (12) at the first end; the second end of the fine filter (10) is connected with the first end of the first two-position two-way electromagnetic reversing valve (13.1) and the first end of the manual three-position four-way reversing valve (17), and a pressure gauge (11) is further arranged on the pipeline connected with the second end of the fine filter (10) and the first end of the manual three-position four-way reversing valve (17); the second end of the first two-position two-way electromagnetic reversing valve (13.1) is connected with the first end of the proportional valve (14); the second end of the proportional valve (14) is connected with the first end of the constant-difference pressure reducing valve (19); the second end of the constant-difference pressure reducing valve (19) is connected with the first end of the second two-position two-way electromagnetic reversing valve (13.2); the second end of the second two-position two-way electromagnetic reversing valve (13.2) is connected with the first end of the main jack operating cylinder (21) and the third end of the manual three-position four-way reversing valve (17); The first end of the second one-way valve (9.2) is connected with the manual pump unit, and the second end thereof is connected with the second end of the first one-way valve (9.1) and the first end of the overflow valve (12); the second end of the overflow valve (12) is connected with the first end of the third one-way valve (9.3), the first end of the manual three-position four-way reversing valve (17) and the fourth end of the proportional valve (14); The second end of the third one-way valve (9.3) is connected with the third end of the proportional valve (14), the second end of the main jack operating cylinder (21) and the second end of the manual three-position four-way reversing valve (17); The fourth end of the proportional valve (14) is connected with the fourth end of the manual three-position four-way reversing valve (17) and the hydraulic accumulator; The pipeline connected with the fourth end of the proportional valve (14) and the fourth end of the manual three-position four-way reversing valve (17) is further provided with a pressure compensator (16); The shuttle valve (18) is further arranged between the second end and the third end of the proportional valve (14).

3. A method for synchronously lifting an airplane by using the hydraulic system for synchronously lifting an airplane according to any one of claims 1-2, characterized in that the method comprises the following steps: A. When the electric pump in the electric control system is used as the power element, first make the cut-off valve (15) in the locked state and the manual three-position four-way reversing valve (17) in the middle position, and then open the first two-position two-way electromagnetic reversing valve (13.1) and the second two-position two-way electromagnetic reversing valve (13.2) after the system detects the signal of the main jack operating cylinder (21) rising or falling; B. When the hand pump in the manual control system is used as the power element, during the rising process of the main jack operating cylinder (21), before rising, the cut-off valve (15) should be completely opened, the manual three-position four-way reversing valve (17) should be pulled to the rising position, and the first hand pump (8.1) and the second hand pump (8.2) should be operated; during the falling process of the main jack operating cylinder (21), before falling, the cut-off valve (15) should be completely locked, then the manual three-position four-way reversing valve (17) should be located in the falling position, and then the cut-off valve (15) should be slowly opened.

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