Complete vehicle action delay troubleshooting method and system

Abstract

The invention relates to the technical field of hydraulic excavators, in particular to a whole vehicle action delay troubleshooting method and system.The pilot pressure is collected through a pressure sensor, a handle is pressed to the maximum limit, and the pressure rise time is recorded to evaluate responsiveness; a pressure difference method and a reverse troubleshooting method are adopted, and a pilot pressure system fault is detected and positioned gradually from a shuttle valve group to a handle by externally connecting a pressure gauge; and the establishing sequence and time difference of the pilot pressure and the main pump pressure are analyzed, system cooperation is evaluated, and finally the main pump is further checked. According to the method, faults are efficiently positioned through a systematic process, the troubleshooting efficiency is remarkably improved, and it is ensured that the action delay problem of new machine mining is accurately solved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic excavators, and in particular to a method and system for troubleshooting whole vehicle action delay faults. Background Art

[0002] In the field of modern engineering machinery manufacturing, hydraulic excavators are a key equipment widely used in various types of engineering construction, and the reliability and stability of their performance are crucial. There are two operating handles in the cab of the hydraulic excavator, which control a total of 8 actions, including boom up, boom down, digging with arm, unloading with arm, digging with bucket, unloading with bucket, left rotation, and right rotation.

[0003] However, in the process of implementing the application, the inventor found that the prior art has the following technical problems: when the newly launched hydraulic excavator is tested, the hydraulic excavator frequently experiences action delays during the execution of the above actions. When the operator controls the hydraulic excavator to perform various actions, such as digging, rotating, lifting, etc., there is an obvious time lag between issuing the operation command and the actual execution of the action by the corresponding parts of the hydraulic excavator, which not only seriously affects the working efficiency of the hydraulic excavator in actual operation, but also has an adverse impact on the progress of the project.

[0004] At present, there is no clear troubleshooting method and effective measures in the industry for this series of action delay problems. Once a problem occurs, it is often necessary for multiple departments within the manufacturing company, including the R&D department, production department, and quality inspection department, to rush to the scene for joint troubleshooting.

[0005] On-site personnel from various departments need to check and analyze each system of the hydraulic excavator, such as the hydraulic system, electrical control system, and mechanical transmission system, one by one, trying to find the root cause of the action delay. This troubleshooting method not only consumes a lot of manpower costs, but also requires a lot of human and material resources to deal with this problem, and the troubleshooting efficiency is extremely low.

[0006] At the same time, due to the lack of a systematic troubleshooting method, there are certain obstacles in the collaboration and information communication between departments, which further prolongs the time for problem solving and forces the delivery cycle of new hydraulic excavators to be extended, causing great economic losses and market competition pressure to the company. Summary of the invention

[0007] In order to solve the deficiencies of the prior art, the present invention proposes a method and system for troubleshooting vehicle action delay faults, so as to at least solve the problem that the prior art solutions cannot quickly troubleshoot the action delay faults of newly-offline hydraulic excavators.

[0008] To achieve the above purpose, the technical solution of the present invention is:

[0009] A method for troubleshooting the delay of the whole vehicle's actions, including:

[0010] Step1: When the whole vehicle shows action delay during the test run of the hydraulic excavator, start troubleshooting. First, collect the pilot pressure value through the pressure sensor installed on the shuttle valve group, and determine whether the pilot pressure value meets the preset threshold range. If it meets, enter Step3; if it does not meet, enter Step2;

[0011] Step2: Check whether the pipeline connections of the hydraulic excavator and the spool connections in the valve blocks are correct. If they are correct, further troubleshoot each connection point on the pilot pipeline of the hydraulic excavator, confirm the cause of the pilot pressure failure one by one, find the failure point, and end the troubleshooting; if they are not correct, it means there is a problem with the pipeline connection, and the troubleshooting ends;

[0012] Step3: Judge whether the time sequence and time difference between the pilot pressure and the main pump pressure meet the preset requirements. If they do not meet, it means there is a cooperation failure between the main pump and the pilot pressure, resulting in the delay of the whole vehicle's actions, and the troubleshooting ends. If they meet, further troubleshoot the main pump.

[0013] A system for troubleshooting the delay of the whole vehicle's actions, including:

[0014] The first troubleshooting module is configured to: when the whole vehicle shows action delay during the test run of the hydraulic excavator, start troubleshooting. First, collect the pilot pressure value through the pressure sensor on the shuttle valve group, and determine whether the pilot pressure value meets the preset threshold range. If it meets, enter the third troubleshooting module; if it does not meet, enter the second troubleshooting module;

[0015] The second troubleshooting module is configured to: check whether the pipeline connections of the hydraulic excavator and the spool connections in each valve block are correct. If they are correct, further troubleshoot each connection point on the pilot pipeline of the hydraulic excavator, confirm the cause of the pilot pressure failure one by one, find the failure point, and end the troubleshooting; if they are not correct, it means there is a problem with the pipeline connection, and the troubleshooting ends;

[0016] The third troubleshooting module is configured to: judge whether the time sequence and time difference between the pilot pressure and the main pump pressure meet the preset requirements. If they do not meet, it means there is a cooperation failure between the main pump and the pilot pressure, resulting in the delay of the whole vehicle's actions, and the troubleshooting ends. If they meet, further troubleshoot the main pump.

[0017] The beneficial effects of the present invention are as follows:

[0018] When a new hydraulic excavator has a situation of action delay during the test run, the present invention takes the pilot pressure as the key entry point, constructs a closed-loop troubleshooting process from the shuttle valve group to the handle in reverse segmentation and then to the main pump pressure. The logic is clear and the levels are distinct, avoiding the blindness of traditional empirical troubleshooting and significantly shortening the fault location time.

[0019] The present invention provides a troubleshooting sequence that progresses step by step and is interlocked. The logic is clear, effectively avoiding blind troubleshooting, greatly improving the fault diagnosis efficiency, and reducing the troubleshooting time and labor costs in workshop production and market services.

[0020] At the same time, this solution comprehensively covers various fault types that cause action delay, including abnormal pilot pressure, pressure coordination imbalance, handle faults, and hydraulic hardware problems, etc., and can accurately identify and solve complex and diverse fault phenomena.

[0021] Particularly importantly, after the new machine is off the production line, strictly following this troubleshooting method for comprehensive detection can discover and eliminate potential fault hazards in advance, provide solid technical support for the quality control of the new machine, ensure that the new machine can operate normally when put into use, avoid work delays and economic losses caused by early faults, help improve the market competitiveness of the product, and deliver more high-quality and reliable hydraulic excavator products to users. Brief Description of the Drawings

[0022] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0023] Figure 1 It is a flowchart of the troubleshooting method for the action delay fault of the new hydraulic excavator whole vehicle described in Embodiment 1.

[0024] Figure 2 It is a connection relationship diagram of the basic structure of the hydraulic excavator described in Embodiment 1.

[0025] In the figure, 1. Handle; 2. Shuttle valve group; 3. Vehicle controller; 4. Throttle valve; 5. Main valve; 6. Pilot hydraulic oil pipe; 7. Main pump solenoid valve; 8. Main pump. Detailed Description of the Embodiments

[0026] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention. The terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0028] As Figure 2 shown, the basic structure of a hydraulic excavator includes: There is an operating handle 1 in the cab of the hydraulic excavator. The operating handle is connected to the pilot hydraulic oil pipe 6 through a mechanical structure. A throttle hole 4 is provided in the oil circuit of each pilot hydraulic oil pipe to control the flow rate of the pilot oil. Each handle 1 corresponds to multiple actions. The actions of the handle 1 will be transmitted to the pilot hydraulic oil pipe 6 mechanically, causing corresponding pressure changes. The pilot hydraulic oil pipe 6 of each action is connected to the shuttle valve group 2. A pressure sensor is installed on the shuttle valve group 2 to detect the pilot pressure signal in the channel of the pilot hydraulic oil pipe 6.

[0029] When there is no action, the spool in the shuttle valve group 2 is in the initial position, waiting to receive the pilot pressure signal. The shuttle valve group 2 is connected in the pilot hydraulic oil pipe 6, used to select the highest pressure signal among multiple pilot signals and ensure the accuracy of the displacement control signal of the main pump. The shuttle valve group 2 can select and switch between different pilot hydraulic oil pipes 6 and transmit the pilot pressure to the corresponding shuttle valve block.

[0030] The vehicle controller 3 is connected to the main pump solenoid valve 7 through a cable and controls the output displacement of the main pump according to the pilot pressure signal. The main pump 8 is connected to the main valve 5 through the main pipeline. The main pump 8 is the power source of the hydraulic system, converting mechanical energy into hydraulic energy and outputting high-pressure hydraulic oil.

[0031] Embodiment 1

[0032] As Figure 1 shown, a method for troubleshooting the vehicle action delay fault includes:

[0033] Step1: When the vehicle action delay occurs during the test run of the hydraulic excavator, start the fault troubleshooting. First, collect the pilot pressure value through the pressure sensor installed on the shuttle valve group, and judge whether the pilot pressure value meets the preset threshold range. If it meets, enter Step3; if it does not meet, enter Step2;

[0034] Further, the pilot pressure value includes: the pilot pressure value collected when the whole vehicle is not operating, or when any handle in the cab is pressed backward to the maximum extent, the computer device is connected to the vehicle controller through the CAN line, and the output current of the vehicle controller is read and the pilot pressure is collected.

[0035] Further, during the process of pressing any handle in the cab backward to the maximum extent, the pilot pressure changes from 0 to the maximum value. Record the moment T1 when the pilot pressure is 0; record the moment T2 when the pilot pressure is the maximum value, and calculate the change time period T2 - T1 of the pilot pressure.

[0036] Judge the responsiveness of the pilot pressure through T2 - T1.

[0037] If the change time period T2 - T1 of the pilot pressure ≤ 300 ms, it means the pilot pressure is normal.

[0038] If the change time period T2 - T1 of the pilot pressure > 300 ms, it means the pilot pressure is abnormal.

[0039] Further, judging whether the pilot pressure value conforms to the preset threshold range includes:

[0040] Case 1: If the pilot pressure is 0 bar ± 0.5 bar when the whole vehicle is not operating, it is determined that the pilot pressure is correct, and further judge the maximum value of the pilot pressure and the change time period T2 - T1 of the pilot pressure during the process of pressing the handle backward to the maximum extent.

[0041] Case 2: If the maximum value of the pilot pressure exceeds 30 bar after pressing any handle in the cab backward to the maximum extent, and the time period T2 - T1 ≤ 300 ms, it is determined that the pilot pressure of the hydraulic excavator is normal and enter Step3.

[0042] Case 3: If any handle in the cab is pressed backward to the maximum extent and the pilot pressure value is greater than 0 bar and less than or equal to 30 bar, it is determined that the pilot pressure of the whole vehicle is abnormal and enter Step2.

[0043] Case 4: If the time period T2 - T1 > 500 ms after pressing any handle in the cab backward to the maximum extent, further check the throttle orifice. If it is confirmed that the throttle orifice is blocked, it is determined that the throttle orifice causes the delay of the whole vehicle's action.

[0044] If the throttle orifice is not blocked, the throttle orifice can be temporarily removed. Then, when any handle in the cab is pressed backward to the maximum extent, if the time period T2 - T1 ≤ 300 ms, it is determined that the too small aperture of the throttle orifice causes the delay of the whole vehicle's action.

[0045] Further, when any handle in the cab is pressed backward to the maximum extent, it means that when the hydraulic excavator has no action, the angle between the handle in the cab and the horizontal plane is 90 degrees. When any handle in the cab is pressed backward to the maximum extent, the angle between the handle in the cab and the horizontal plane is at least greater than 17 degrees.

[0046] It should be understood that the pilot pressure is the pre-signal pressure that controls the flow direction and flow rate of the hydraulic oil in the main oil circuit, and its value and responsiveness can intuitively reflect potential problems in the hydraulic system.

[0047] The advantages of the above technical solution are: by checking the pilot pressure value, it is possible to quickly determine whether there is a problem of insufficient pressure or abnormal fluctuation in the hydraulic system, resulting in the delay of the vehicle's actions.

[0048] Step2: Check whether the pipeline connections of the hydraulic excavator and the connections of the spool valves in each valve block are correct. If correct, further troubleshoot each connection point on the pilot pipeline of the hydraulic excavator, confirm the cause of the pilot pressure failure one by one, find the fault point, and end the troubleshooting; if incorrect, it means that there is a problem with the pipeline connection, and the troubleshooting ends.

[0049] It should be understood that the connection sequence of each component of the pilot pipeline of the hydraulic excavator is: handle, pilot hydraulic oil pipeline, and shuttle valve group, and a pressure sensor is installed on the shuttle valve group.

[0050] Further, the troubleshooting of the pipeline connections of the pilot pipeline of the hydraulic excavator and the connections of the spool valves in each valve block includes obtaining the design drawings of the pipeline connections of the pilot pipeline of the hydraulic excavator and the connections of the spool valves in each valve block, and confirming whether the pipeline connection direction, connection position, and connection sequence of the pilot pipeline of the hydraulic excavator and the connections of the spool valves in each valve block are consistent with the design.

[0051] Further, the differential pressure reverse troubleshooting method is used to troubleshoot each connection point on the pilot pipeline of the hydraulic excavator. The differential pressure reverse troubleshooting method includes:

[0052] (1-1) Connect an external pressure gauge to the shuttle valve group, and press any handle in the cab backward to the maximum extent;

[0053] If the value shown on the external pressure gauge is normal, it is determined that the pressure sensor fails and causes incorrect readings, and enter Step3;

[0054] If the value shown on the external pressure gauge is incorrect, it is determined that the pressure sensor works normally, and enter (1-2);

[0055] (1-2) Connect an external pressure gauge to the pilot hydraulic oil pipeline, and press any handle in the cab backward to the maximum extent;

[0056] If the value shown on the external pressure gauge is normal, it is determined that the shuttle valve group fails and causes the delay of the vehicle's actions;

[0057] If the external pressure gauge shows an incorrect value, it is determined that the shuttle valve group is working properly and proceed to (1-3).

[0058] (1-3) Connect the external pressure gauge to any one of the handles in the cab and press any one of the handles in the cab backward to the maximum extent.

[0059] If the external pressure gauge shows a normal value, it is determined that the pilot hydraulic oil pipe causes the vehicle to move slowly.

[0060] If the external pressure gauge shows an abnormal value, it is determined that the handle causes the vehicle to move slowly.

[0061] The advantages of the above technical solution are as follows: By gradually narrowing down the fault range through reverse sectional troubleshooting from the shuttle valve group to the handle, it avoids blind disassembly and disorderly detection, ensures that each component can be inspected targeted, and forms a closed-loop diagnostic process.

[0062] Step3: Determine whether the time sequence and time difference of the pilot pressure and the main pump pressure appear meet the preset requirements. If not, it indicates a fault in the coordination between the main pump and the pilot pressure, resulting in the vehicle moving slowly, and the fault troubleshooting ends. If so, further troubleshoot the main pump.

[0063] It should be understood that in the hydraulic system, the pilot pressure controls the opening or closing of the main valve through the pilot valve, thereby regulating the flow and pressure of the hydraulic system, while the main pump pressure is the power source for the actual operation of the hydraulic system. If the establishment sequence of the pilot pressure and the main pump pressure is incorrect, it will lead to system response delay, unstable operation, and even equipment failure.

[0064] The computer device connects to the vehicle controller through the CAN line to obtain the sequence of the establishment of the pilot pressure and the main pump pressure, and determines whether the working sequence of the hydraulic system is normal. If the pilot pressure appears before the main pump pressure, it indicates that the working sequence of the hydraulic system is normal, excluding the delay in the vehicle movement caused by the incorrect coordination of the pilot pressure and the main pump pressure.

[0065] If the main pump pressure appears before the pilot pressure, it indicates that the working sequence of the hydraulic system is abnormal. In the above Step1, the delay in the vehicle movement caused by the pilot pressure system has been excluded. The computer device connects to the vehicle controller through the CAN line to read the time when the pilot pressure and the main pump pressure are established. The time when the pilot pressure is established is recorded as T4, the time when the main pump pressure is established is T5, the time when the actual current is established is T6, and the time difference between the establishment of the pilot pressure and the main pump pressure is recorded as T5-T4.

[0066] If the time difference |T5 - T4| between the pilot pressure and the main pump pressure is approximately 50 ms, it indicates that the cooperation between the pilot circuit of the hydraulic system and the main pump is normal, ruling out the problem of action delay of the whole vehicle caused by the cooperation between the pilot pipeline and the main pump of the hydraulic excavator.

[0067] If the time difference T5 - T4 between the pilot pressure and the main pump pressure is 50 ms, then according to the specification of the proportional valve on the main pump, the current of the proportional solenoid valve on the main pump needs to be increased to the maximum value allowed by this proportional valve. If during the process that the pilot pressure reaches the value of 30 bar, the change time period T2 - T1 of the pilot pressure > 300 ms, then consider the leakage of the pilot oil, resulting in the action delay of the whole vehicle.

[0068] If the change time period T2 - T1 of the pilot pressure ≤ 300 ms, but the actual current establishment time T6 obtained by the computer device connected to the vehicle controller through the CAN line > 200 ms, and at the same time the main pump pressure establishment time T5 > 200 ms, then it is determined that there is a problem with the responsiveness of the solenoid valve on the main pump, resulting in the action delay of the whole vehicle.

[0069] Embodiment 2

[0070] A system for troubleshooting the action delay of the whole vehicle, comprising:

[0071] The first troubleshooting module is configured to: when the whole vehicle has an action delay during the test run of the hydraulic excavator, start troubleshooting. First, collect the pilot pressure value through the pressure sensor installed on the shuttle valve group, and judge whether the pilot pressure value meets the preset threshold range. If it meets, enter the third troubleshooting module; if it does not meet, enter the second troubleshooting module;

[0072] The second troubleshooting module is configured to: check whether the pipeline connection of the hydraulic excavator and the connection of the spool in the valve block are correct. If they are correct, further troubleshoot each connection point on the pilot pipeline of the hydraulic excavator, confirm the cause of the pilot pressure fault one by one, find the fault point, and end the troubleshooting; if they are not correct, it means that there is a problem with the pipeline connection, and the troubleshooting ends;

[0073] The third troubleshooting module is configured to: judge whether the time sequence and time difference between the pilot pressure and the main pump pressure meet the preset requirements. If they do not meet, it means that there is a cooperation fault between the main pump and the pilot pressure, resulting in the action delay of the whole vehicle, and the troubleshooting ends. If they meet, further troubleshoot the main pump.

[0074] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for troubleshooting the vehicle's overall motion delay, characterized in that, Including: Step 1: When the whole vehicle of the hydraulic excavator shows a delay in operation during the test drive, start troubleshooting. First, collect the pilot pressure value through the pressure sensor installed on the shuttle valve group, and determine whether the pilot pressure value meets the preset threshold range. If it meets, go to Step 3; if it does not meet, go to Step 2. Step 2: Check whether the pipeline connection of the hydraulic excavator and the spool connection in the valve block are correct. If they are correct, further troubleshoot each connection point on the pilot pipeline of the hydraulic excavator, confirm the cause of the pilot pressure failure one by one, find the fault point, and the troubleshooting ends; if they are not correct, it means that there is a problem with the pipeline connection, and the troubleshooting ends. Step 3: Judge whether the time sequence and time difference between the pilot pressure and the main pump pressure meet the preset requirements. If they do not meet, it means that there is a problem with the cooperation between the main pump and the pilot pressure, resulting in a delay in the operation of the whole vehicle, and the troubleshooting ends. If they meet, further troubleshoot the main pump.

2. The method for troubleshooting vehicle operation delay faults according to claim 1, characterized in that, The pilot pressure value includes: the pilot pressure value collected when the whole vehicle has no operation, or when any handle in the cab is pressed backward to the maximum extent, the computer device is connected to the vehicle controller through the CAN line, and the output current of the vehicle controller is read and the pilot pressure is collected.

3. The method for troubleshooting the vehicle operation delay fault according to claim 2, wherein, Pressing any handle in the cab backward to the maximum extent means: the pilot pressure changes from 0 to the maximum value, record the moment T1 when the pilot pressure is 0; record the moment T2 when the pilot pressure is the maximum value, and calculate the change time period T2 - T1 of the pilot pressure.

4. The troubleshooting method for the vehicle operation delay fault according to claim 1, characterized in that, Judging whether the pilot pressure value meets the preset threshold range includes: if the pilot pressure is 0 bar ± 0.5 bar when the whole vehicle has no operation, it is determined that the pilot pressure is correct, and further judge the maximum value of the pilot pressure and the change time period T2 - T1 of the pilot pressure during the process of pressing any handle in the cab backward to the maximum extent.

5. The troubleshooting method for the vehicle motion delay fault according to claim 1, wherein Judging whether the pilot pressure value meets the preset threshold range also includes: if the time period T2 - T1 is greater than 500 ms after pressing any handle in the cab backward to the maximum extent, further troubleshoot the throttle orifice. If it is confirmed that the throttle orifice is blocked, it is determined that the throttle orifice causes the delay in the operation of the whole vehicle.

6. The troubleshooting method for the vehicle action delay fault according to claim 1, wherein Troubleshooting each connection point on the pilot pipeline of the hydraulic excavator includes: using the differential pressure reverse troubleshooting method to troubleshoot each connection point on the pilot pipeline connection of the hydraulic excavator.

7. The troubleshooting method for vehicle movement delay faults according to claim 1, wherein Judging whether the time sequence and time difference between the pilot pressure and the main pump pressure meet the preset requirements includes: the computer device connects to the vehicle controller through the CAN line to obtain the sequence established by the pilot pressure and the main pump pressure, and judge whether the working sequence of the hydraulic system is normal. If there is pilot pressure first and then main pump pressure, it means that the working sequence of the hydraulic system is normal, and the error in the cooperation between the pilot pressure and the main pump pressure causing the delay in the operation of the whole vehicle is excluded.

8. The troubleshooting method for vehicle movement delay faults according to claim 1, characterized in that, Judging the time sequence and time difference between the pilot pressure and the main pump pressure to see if they meet the preset requirements further includes: The computer device is connected to the vehicle controller through the CAN line to read the establishment times of the pilot pressure and the main pump pressure. The establishment time of the pilot pressure is denoted as T4, the establishment time of the main pump pressure is T5, and the time difference between the establishment times of the pilot pressure and the main pump pressure is denoted as T5 - T4.

9. The troubleshooting method for the vehicle operation delay fault according to claim 1, wherein Judging the time sequence and time difference between the pilot pressure and the main pump pressure to see if they meet the preset requirements further includes: If the change time period of the pilot pressure T2 - T1 ≤ 300 ms, but the actual current establishment time T6 obtained by the computer device connecting to the vehicle controller through the CAN line > 200 ms, and at the same time the main pump pressure establishment time T5 > 200 ms, it is determined that there is a problem with the solenoid valve responsiveness on the main pump, resulting in a vehicle operation delay.

10. A vehicle operation delay fault troubleshooting system, characterized in that, Including: A first troubleshooting module, which is configured to: When the whole vehicle of the hydraulic excavator has an operation delay during the test drive, start troubleshooting. First, collect the pilot pressure value through the pressure sensor on the shuttle valve group, and judge whether the pilot pressure value meets the preset threshold range. If it meets, enter the third troubleshooting module; if it does not meet, enter the second troubleshooting module; A second troubleshooting module, which is configured to: Check whether the pipeline connection of the hydraulic excavator and the spool connection in the valve block are correct. If they are correct, further troubleshoot each connection point on the pilot pipeline of the hydraulic excavator, confirm the cause of the pilot pressure fault one by one, find the fault point, and end the troubleshooting; if they are not correct, it means that there is a problem with the pipeline connection, and the troubleshooting ends. A third troubleshooting module, which is configured to: Judge whether the time sequence and time difference between the pilot pressure and the main pump pressure meet the preset requirements. If they do not meet, it means that there is a problem with the cooperation between the main pump and the pilot pressure, resulting in a vehicle operation delay, and the troubleshooting ends. If they meet, further troubleshoot the main pump.

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