In the high pressure condition, the increase of internal clearance of gear pump will aggravate the leakage inside the pump and seriously affect its volumetric efficiency. Axial clearance and radial clearance are the two main ways of internal leakage of the pump, and the mathematical model of liquid leakage and clearance value in the two kinds of clearance is analyzed. The main influencing factors of axial clearance include: gear shaft deflection deformation, gear shaft eccentricity and pump body wear and structural deformation; while radial clearance is mainly affected by gear pump end cover deformation and multi-physical field coupling, and the research conducted at home and abroad for these five aspects is reviewed. In order to control the amount of internal clearance leakage in the pump, the research content of optimizing and controlling the internal clearance is reviewed. Finally, it is pointed out that understanding the local size variation of the gear pump clearance is an important reference for studying the flow characteristics and internal structure design of the pump.

In order to solve the problem that the hydraulic cylinder retracting speed is too fast when the fork of electric forklift truck is carrying the weight, which is prone to damage the cylinder block and pipeline and the fork holding weight is different, the hydraulic cylinder extending speed is not controllable, the hydraulic lifting system of electric forklift truck is optimized, and simulation verification is carried out. The hydraulic lifting system is designed according to the design manual. The working pressure of the primary system is 16MPa. The accumulator is parallel to absorb the flow pulsation on the outlet circuit of the hydraulic pump. The speed regulating valve is configured on the rodless chamber inlet circuit of the hydraulic cylinder to realize the pressure compensation for different weights and make the lifting speed controllable. The hydraulic cylinder piston rod provides back pressure when the load is retracted to avoid the piston rod free fall damage to the hydraulic cylinder; The hydraulic components are designed and selected. Choose CBG2100-BF100 hydraulic pump and HSGL-100/70E-231-3000×3280 hydraulic cylinder, 3WE10E31B/CG24N9Z4 electromagnetic reversing valve and RVP30-10B check valve, DBDS30P10B sequence valve, THF-G10 speed regulating valve ; The hydraulic system is studied by the principle of power key and graph, and the dynamic characteristics of the hydraulic system are studied by digital simulation. The mathematical model of the hydraulic system is built by the simulation software AMESim, and the parameters of key components are simulated. The simulation results show that it takes 8 s for the cylinder piston rod of the optimized hydraulic system to fully retract without oscillation, and the operation is stable. The oil port flow rate of the cylinder piston rod is 87 L/min when the cylinder piston rod is retracted, and the flow pulsation generated by the hydraulic pump is absorbed by the accumulator. The system runs stably and meets the design requirements, and the hydraulic lifting system is theoretically feasible and reliable.

ABS braking system is an important part to ensure the safety performance of the car, and a comparative study of automotives ABS control strategies is conducted for the problems of nonlinearity and time-variability of the braking system in the braking process. The linear braking process is studied and analyzed, and an anti-lock hydraulic system with a single wheel is established based on AMESim, and the single-wheel dynamics model is established used Simulink, and a fuzzy PID control strategy with slip rate error and change rate as input and a self-seeking optimal control strategy with brake torque change rate as input are used. The two control strategies are simulated for ABS braking on a single dry road, wet road and 1.5 s after braking when the wet road changes abruptly to dry road for multiple road conditions at a vehicle speed of 90 km/h, and the braking results are compared. The results show that the fuzzy PID and self-seeking control methods can prevent wheel locking in the braking process, and the self-seeking control method not only has shorter braking time, but also can better cope with the sudden change of road conditions, which verifies that the self-seeking control has stronger robustness and better braking effect.

The corrosion resistance of rubber seals for DME/LPG composite gas is crucial for ensuring the reliability and safety of equipment. A pressured immersion test vessel for DME/LPG composite gas has been designed and fabricated, with a focus on investigating the corrosion resistance of RDME6660 rubber. It has been demonstrated that the use of EPDM rubber in DME storage equipment has significant safety risks. RDME6660 rubber has been exhibited superior resistance to DME corrosion compared to the perfluoroether rubber, surpassing industry standard technical indicators by a factor of 50. It has been shown that RDME6660 rubber can be safely applied under conditions of pure liquefied DME, pure LPG, and any ratio of DME to LPG composite gas.

The TSG D7002—2006 Type Test Rules for Pressure Pipeline Components require revision and updating of the original content due to the long service life of the rules and the requirements of the new system. The new version of the rules was released on July 7, 2023 and implemented on October 1. This article compares the similarities and differences between the new and old versions of the rules, interprets the new provisions, and refers to the data provided by the National Seal Product Quality Inspection and Testing Center to analyze the current qualified rate of type tests in the domestic special equipment pressure pipeline component industry. It summarizes the shortcomings and proposes corresponding suggestions.

With the rapid development of Chinese industry, as an important component of control valves, the market demand for regulating valves is constantly increasing, but new challenges are also being faced, and the flow capacity of regulating valves is also constantly improving. Based on this, the study of the flow capacity of the regulating valve is very important. Starting from the flow channel structure of the regulating valve, simulation and experimental analysis are used to analyze the internal flow characteristics of two mainstream regulating valves on the market ^[1]. The flow coefficient Cv of the two regulating valves is obtained. The flow capacity of the G1 series regulating valve has been significantly improved compared to the G2 series regulating valve, which is approximately 21.4% higher, Through the study of the flow capacity of the regulating valve, key factors affecting its flow performance have been discovered, which has important guiding significance for the optimization and improvement of the regulating valve.

High precision CNC machine tools are a highly integrated and complex electromechanical hydraulic automation control system. Faults between components can easily lead to the instability of CNC machine tools. In response to the problem of fault diagnosis and response of high-precision CNC machine tools, based on the entire structure of the machine tool control system, fault diagnosis function systems are divided for each subsystem, and a high-precision CNC machine tool hydraulic control system fault monitoring status machine is constructed, Using a differential threshold fault monitoring strategy for fault diagnosis of related components, graded fault response was performed for different fault severity events. Finally, the availability of the fault diagnosis method was verified in a high-precision CNC machine tool hydraulic control system fault diagnosis simulation experimental environment. After analyzing the experimental results, it can be seen that the fault diagnosis method can quickly and effectively monitor the fault status of the entire machine tool hydraulic control system.

Hydraulic piston pumps commonly used in aircraft, are normally designed with straight-shaft, constant-pressure and variable-displacement. In order to reduce pulsation and improve stability during high-frequency movements, swash plates of this kind of pump are also designed with eccentricity and cross angles. For the hydraulic piston pump with swash plate eccentricity and cross angle, a motion characteristics analysis method of piston and sliding shoe, which can comprehensively consider the effects of swash plate eccentricity, cross angle, swash plate inclination angle and rotation speed, is proposed. For a certain type of aviation hydraulic piston pump, the displacement and velocity characteristics of the plunger under different eccentricity and cross angles, as well as the motion trajectory of the sliding shoe in the plane of the swash plate, were compared and analyzed. The motion characteristics of the piston in the dead zone profoundly affect the output flow and pressure pulsation of the hydraulic piston pump. According to the general criteria for the design of the dead zone of the distribution plate of the hydraulic pump, the dead zone of the distribution plate was determined, and the motion characteristics of the piston in the dead zone were analyzed. The motion characteristics of the piston in the dead zone profoundly affect the output flow and pressure pulsation of the hydraulic piston pump. The analysis method proposed in this paper can describe the motion characteristics of swash plate rotation (flow switching), and has the characteristics of high calculation efficiency and high accuracy of results, which can be used for the design optimization of hydraulic piston pump with the goal of reducing pulsation.

During the use of a certain pneumatic absolute pressure regulator, the product failed to open and the outlet pressure was low. Based on MATLAB, this article modeled and analyzed the two position four way valve inside the product, simulated the movement of the valve body spring and damping under flight vibration conditions, and established an animation simulation. The results showed that the double spring and double damping valve bodies could not reliably press the valve seat under this vibration condition, and the opening increased by 0.13~0.20 mm, resulting in a loss of closing function, Causing an increase in feedback chamber pressure and a low outlet pressure of the valve; Simulink simulates the electromagnetic valve model and obtains the difference between the electromagnetic attraction and the interference dynamic friction force under different voltages. The results show that the difference is less than 3 N, and the electromagnetic iron is energized without action, and the product air circuit cannot be opened; By changing the double spring and double damping structure to a single spring and single damping structure, improving the electromagnetic core and matching size, and improving the graphite ring dynamic seal, the fault situation is reproduced through experiments to verify the improvement measures, providing reference for the design of pneumatic pressure regulators.

For hydraulic system packers, a study was conducted to use polyether polyurethane elastomers to make sealing components such as rubber barrels, sealing rings, and gaskets for underground hydraulic packers, and to add anti protrusion parts to further improve the sealing performance of the packers. Finally, introducing inlet pressurization further improves the performance of the hydraulic system. The results showed that the tensile strength, elongation at break, and compression set rate of the packer rubber cylinder prepared with polyether polyurethane elastic system were 37 MPa, 490%, and 52%, respectively, after half a month of immersion, which showed better performance than natural rubber. Compared to packers without anti protrusion structures, packers with anti protrusion structures have higher contact surface stress, which has a significant positive impact on the performance of hydraulic system packers. After introducing inlet pressurization, the high-pressure chamber pressure and piston displacement of the hydraulic system increased by 4.6% and 8.9%, respectively. The results indicate that measures such as optimizing sealing structure, improving sealing materials, and improving sealing technology can effectively improve the pressure stability, system response stability, and sealing performance of hydraulic systems, providing new ideas and methods for improving hydraulic system performance.

A detailed model for a rotationally balanced constant-pressure dual-row axial piston pump was meticulously developed, followed by an extensive AMESim simulation. This simulation investigated how outlet pressure impacts flow, the correlation between outlet pressure and the distribution plate's rotation angle, and the pump's dynamic behavior with sudden changes in the variable orifice signal. The analysis considered the nuanced effects of reset spring stiffness in the variable mechanism and valve stiffness in the pressure control valve. The findings highlighted a decrease in outlet flow with rising outlet pressure and an increased rotation angle of the distribution plate. A stiffer reset spring led to quicker dynamic response and reduced overshoot in the pump. Conversely, a larger valve core diameter slowed down the pump's dynamic response, prolonged steady-state attainment, and intensified flow and pressure oscillations by amplifying the distribution plate's rotation during that phase.

Roadheader is often used in tunnel construction, and it is developing towards the direction of large-scale. The power demand is increasing, which puts forward the demand of high pressure and large displacement for the core component pump of the drive system. The service life and reliability of the pump are directly related to the technical level of the roadheader. Based on this, this paper proposes a life prediction method for a domestic axial piston pump, establishes an accelerated life model, extracts key characteristic parameters through accelerated test, obtains the accelerated life of the pump, and calculates the life of the pump under rated working conditions. Through the actual loading application of the pump in the roadheader, the accuracy of the life prediction is verified, and complete the reliability evaluation of the confidence interval based on the predicted lifespan of the pump.

Jet pipe electro-hydraulic servo valve is the core control component of electro-hydraulic servo control system, which is widely used in aerospace, ship and other national defense and military fields. Torque motor is the core component of jet pipe electro-hydraulic servo valve, its performance directly affects the whole performance of the servo valve. Focusing on the performance of the gantry torque motor, the AMESim simulation model of the torque motor is built. The static and dynamic characteristics of the gantry torque motor are simulated, and the correctness of the simulation results is verified by experiments. The results show that the static linearity and symmetry of the gantry torque motor are 6.825% and 2.449%. The rise time of dynamic step response is 2.84 ms. The amplitude frequency width is 122 Hz, and the phase frequency width is 245 Hz.

For a certain double end mechanical seal, the temperature field of carbon graphite and hard alloy with silicon carbide in different temperatures of clean water and hydraulic oil was analyzed. The results showed that when the flushing fluid was water, the flushing amount increased, but the temperature rise of the sealing ring did not decrease significantly. When the flushing fluid was oil, the flushing amount increased, and the temperature rise of the sealing ring decreased significantly; The maximum temperature of the sealing end face when hydraulic oil is used as flushing fluid is 25~42 ℃ higher than that when water is used as flushing fluid; When water is used as the flushing solution, the highest temperature rise of the sealing ring is about 11 ℃ at different temperatures. Reasonable control of the flushing solution temperature can effectively solve the problem of temperature rise on the sealing ring end face; When hydraulic oil is used as the flushing fluid, the temperature rise of the sealing ring end face is between 33 ℃ and 54 ℃. Simply controlling the flushing fluid temperature and flow rate cannot effectively reduce the temperature rise of the sealing ring. Under this working condition, hard alloy has better performance on silicon carbide pairs.

Aiming at the crucial issues of serious friction and wear and large leakage in the key friction pair on the axial piston pump, the influence factors of pressure and shear flow are introduced, the oil film thickness equation considering the viscous-temperature effect was established, and the lubrication and leakage characteristics of the piston pair are analyzed using finite element method, and the following conclusions are obtained: When considering the viscous-temperature characteristics of the lubricant, the maximum oil film pressure is obviously greater than the film pressure without considering the viscous-temperature characteristics, and the minimum oil film thickness is much smaller than the minimum film thickness; with the increase of temperature, the oil film pressure gradually increases, and the film thickness gradually decreases. The leakage amount considering the viscous-temperature characteristics is obviously greater than the leakage amount without considering the viscous-temperature characteristics. When the temperature is greater than 60 ℃, the leakage rate increases significantly. With the increase of temperature, the leakage amount at different contact lengths increases nonlinearly. When the contact length is 17 mm, the leakage amount is the largest and the slope of the vary curve is the steepest, when the unilateral clearance increases above 3 μm, the leakage ratio increases significantly. The research can provide a reference for the accurate theoretical design of the piston pair and safe and stable operation of piston pumps.

Analyze the control principle for the vibration problem of leveling micro operation of a certain type of positive flow hydraulic excavator, and establish a mathematical model for the performance of two composite micro operations: boom lifting and bucket rod retraction. Build a test platform to evaluate the combined impact and vibration performance of boom lifting and stick retraction from the perspectives of hydraulic, vibration, and noise. When pressure jitter occurs, the pilot pressure for boom lifting stabilizes between 1.721 and 1.751 MPa; However, the variation range of the pilot pressure in the stick retraction is relatively large, ranging from 1.423 to 1.675 MPa. The pressure jitter during the boom lifting and micro operation of the stick retraction is closely related to the variation of the pilot pressure in the stick retraction. However, the driver's position did not exhibit strong impact shaking, and the Z-direction isolation rates of each suspension were between 21 and 25 dB, indicating good isolation performance; The sound pressure level in the cab is between 74~78 dB, with good noise insulation performance. In addition, the lifting time of the P7 gear boom of the experimental prototype is 4.5 s, the retraction time of the stick is 2.5 s, and the composite time of the boom lifting and stick retraction is 3.2 s. When the speed is 1650 r/min and the torque load rate is 72%, the leveling efficiency test value is 520 times/h, and the leveling fuel consumption test value is 28.30 L/h, indicating better leveling economy.

For a typical fault of a type of aircraft landing gear, based on its working principle, the fault tree analysis method was used to analyze and diagnose the fault. A fault tree and fault structure function with the fault phenomenon as the top event were established, and all basic events corresponding to the fault were obtained.Combined with the prior probability of the basic event of such faults calculated by a certain company, the failure probability of the fault phenomenon was calculated through importance, and a fault diagnosis process was developed to provide a basis and reference for the efficient diagnosis, analysis, and maintenance of such faults in this type of aircraft.

This paper based on hydraulic landing gear test bed, combined hydraulic system, landing gear system, landing gear structure to carry out comprehensive test. Study on the working characteristics of an aircraft landing gear retraction system. Obtain the influence of hydraulic system output flow rate and switch control logic on the landing gear retraction and retraction characteristics. Meanwhile, the typical fault of landing gear down and hard unlocked during system test is analyzed. It is determined that the landing gear is hard unlocked due to back pressure on the lowering pipeline during the lift action when lowering the landing gear. Through the comparative analysis of theoretical research and experimental results, accurately locate the position where fault occurred, further deepen the understanding of the system.

With the increasing emphasis on oxygen health care, the demand for oxygen machines for health care purposes has been growing year by year in the market, and the oxygen machine solenoid valve is a key component of medical health oxygen machines. The working principle of the oxygen machine and several main types of oxygen machine solenoid valves currently on the market are introduced, along with the performance characteristics of each oxygen machine solenoid valve.

The seawater environment is harsh and complex, and the metal parts of conventional mechanical seals will be severely corroded in the seawater environment. The friction pairs are prone to failure and leakage under the wear of hard impurities in seawater, greatly reducing the service life of mechanical seals. To ensure the safety and stable operation of underwater equipment, a mechanical seal is designed for underwater use. The metal components are made of duplex stainless steel material, which has good corrosion resistance. The friction pair adopts a “hard and hard” structural form, which can resist the wear of seawater impurities. In addition, the non compensating ring end face is treated with a hard coating, which improves surface hardness and reduces surface friction coefficient. The seal was subjected to a continuous 5 h running simulation test, using oil as the process medium, and the leakage amount reached 0.33 mL/h under the working condition of pressure of 0.1 MPa.

The traditional direct relief valve is limited by the structural dimension of adjustment part and adjusting torque caused by the spring stiffness. resulting in a maximum nominal diameter of DN30 and a flow rate of only 330 L/min, which is powerless for the hydraulic system exceeding this flow rate. The editor created a new two-way cartridge valve structure with mature application, and broke through the traditional design of valve core spring chamber without pressure oil. The pressure oil at the bottom of the valve core is introduced into the spring chamber through the middle channel of the valve core or the X channel of the external oil circuit block and the cover plate body, changing the balance between the traditional spring pre pressure and the hydraulic force of the valve core bottom diameter D₁, so as to balance the force of the annular area composed of the diameters D₁ and D₂. In this way, the spring stiffness is reduced, and even reduced the structural dimension of adjustment part and adjusting torque. By using this principle, the actual diameter of the new direct relief valve can reach DN50 and the flow can reach 2500 L/min. The additional function option of the valve is designed: the pressure oil in the spring chamber of the valve element is returned to the oil tank by adding a control valve to realize the secondary pressure. A two-way relief valve is derived to enable A and B ports to overflow each other.

Focus on hydraulic pressure fluctuations in traditional accumulators during energy storage and release, a spring-based constant pressure accumulator is proposed. The operational principle of the accumulator is analyzed, with the profile curve equation for the critical component derived and solved. Key parameters for an accumulator in a specific hydraulic system are designed. A simulation model is constructed in ADAMS software to test the performance of the accumulator under varying flow conditions. It achieved a force deviation below 1% during stable operation, serving as a reference for the design of hydraulic energy storage systems.

In order to improve the fault diagnosis rate of the landing gear of a certain type of aircraft, FTA and RBF neural network were used to diagnose the common faults of the landing gear. Firstly, according to the schematic diagram of the landing gear, the fault tree and the structure function of the fault were established by FTA, and all the minimal cut sets were obtained, and the failure probability was calculated. Then, the training samples of RBF neural network were screened according to the importance of the minimal cut sets.Finally, based on the fault statistics of a domestic maintenance unit, the fault diagnosis model was established by using the RBF neural network, and the model was trained and tested. The results show that the failure rate of the common fault is 71.60% by FTA. The average prediction error of the fault diagnosis method using “FTA+RBF” is 1.0%.

Basing on four axis single hydraulic technology which has a simple structure to design a hydraulic press system. To control the feed andreturn speed by component and travel switch cooperation. To produce the stainless steel ball knob by pressure changed mold inside. After mass production, we can get qualify products.

Nozzle plays an important role in high pressure water jet cleaning technology. In order to give full play to the turbulent effect of gas-liquid two-phase jet, a oscillating exchange high-pressure water jet device is designed. High pressure water with small diameter flows out with high speed jet, and negative pressure is generated in the chamber due to its fast velocity, and water and gas are uniformly mixed. High pressure water flows through the upper nozzle to the mixing chamber, and gas and high speed jet are uniformly mixed with the same speed, and then shot out together after the throat completes the shock exchange. The real results of cleaning parameters show that the impact force of jet increases with the increase of target distance, and the cleaning effect weakens with the decrease of the impact force. The optimal target distance is similar at different installation angles, and the pressure and diameter of the nozzle will affect the optimal target distance. In the core area of high pressure water jet, the water flow from a small range continues to increase, and the decontamination cost and energy consumption will increase due to the increase of decontamination pressure.

In order to improve the efficiency of automatic fruit picking, deeply implement the concept of technology strengthening agriculture and smart agriculture, taking tomato picking as an example, a two axis harvesting robotic arm is designed according to the functional requirements of tomato fruit picking process and the structural characteristics of human arms, using ANSYS Workbench software to optimize its structure. The end effector is designed as a flexible pneumatic driven robotic arm, building a robotic arm and simulating its motion posture in the RobotStudio, finally, the camera, a key component of the visual system of the tomato picking robot, is set up and programmed for control. The construction of an automatic recognition tomato picking robotic arm control system has been completed.

In order to reduce the noise of the bent-axis piston motor and improve the stability of the hydraulic system, this paper analyzes the vibration and noise characteristics of the plunger motor shell. Firstly, the internal excitation source and vibration transmission path of the motor were analyzed. Then, to determine the modal frequency that has the greatest impact on the dynamic performance of the shell structure and the area where the structural vibration is severe during operation, modal analysis and harmonic response analysis are sequentially performed on the shell in ANSYS. Finally, noise experiments were conducted on the plunger motor in a semi-anechoic chamber to verify the accuracy of the simulation results. The research conclusion provides a new idea for the vibration and noise reduction technology of the plunger motor.

Taking the high temperature and pressure ball valve as the research object, the finite element model of the contact between the valve seat and the ball is established by theoretical calculation of the necessary specific pressure and spring pre-tightening force. The sealing characteristics and contact fatigue life of the valve seat sealing surface under different medium pressures are analyzed. The analysis results show that with the increase of internal medium pressure, the equivalent stress and sealing specific pressure on the ball valve and the valve seat show an upward trend, and the maximum sealing specific pressure appears at the edge of the outer ring where the sealing surface contacts the ball. The results of contact fatigue life analysis show that the contact fatigue damage at the edge of the outer ring where the sealing surface contacts with the sphere reaches the maximum and the contact fatigue life is the minimum, which is the same as the distribution position of the maximum sealing specific pressure. This also shows that this position belongs to the weak area under long-term working conditions and should be paid attention to in the process of design, processing and maintenance.

In hydraulic fluid transmission systems, ISO 6149 inner cone sealing structure is widely used because of its good sealing effect, but this sealing structure has some shortcomings, such as cone hole is difficult to process, easy to cut the seal ring during installation, so a new sealing structure design method is proposed in this paper, through the comparison of ISO 6149 inner cone sealing structure, the sealing principle, characteristics and advantages of this type of sealing structure and method to determine the sealing parameters is given, the application is verified by practical application and simulation.

Based on the analysis of different working conditions of the Lower Marine Riser Package (LMRP), building the models and analysis for coiled tubing cutting gate, wireline cutting valve and time-delay drive device on the AMESim platform, then study the Hydraulic System on different working conditions. Using the AMESim platform to carry out joint simulation of machinery, electrical and hydraulic equipment, analysis and matching parameters, then verifying that the hydraulic system configuration can complete the task of “first disengagement-tieback-second disengagement”, providing the oretical guidance for the engineering development of the hydraulic system of the Lower Marine Riser Package.

In order to detect the composite anti-interference ability of multi-way valves, this paper uses AMESim software to simulate the multi-way valve produced by a domestic manufacturer, and compares the simulation results with the test results to measure the flow rate at the load end of the multi-way valve under different loads, and the comparative results show that with the increase of load pressure, the leakage of multi-way valves increases; When the load force reaches 35 MPa, the safety valve of the LS circuit overflows, and the flow rate detected at the load end drops significantly; Under the underflow condition, the traffic distribution ratio of the high load side is lower than that of the low load side.

Ball screw is a key transmission component in electro-hydraulic servo equipment, and its structural design will have a direct impact on the mechanical properties and further affect the stability and life of its transmission. The system was analyzed by ABAQUS solver to study the ball load carrying situation and the influence of nut structure on its load. The results show that the secondary development of ABAQUS based on Python can realize the whole process of finite element parametric modeling and static analysis of ballscrew sub-systems, which provides data and methods for the subsequent study of the optimization of the structural design of the nut returner and the selection of materials.

As a safety valve for axial piston variable displacement pumps or axial piston variable displacement motors, the performance of the pilot operated high-pressure relief valve will directly affect the safety and reliability of the axial piston variable displacement pump, axial piston variable displacement motor, and system. This paper introduces the working principle and mathematical calculations of a certain type of high-pressure relief valve in our company, and establishes a simulation model using AMESim to explore the effects of the pre tightening force of the pilot spring and the main valve spring on the opening pressure, pressure overshoot, pressure overshoot stabilization time, and unloading time of the high-relief valve. This has guiding significance for the design of high-pressure relief valve.

This article briefly introduces the development trend of dedicated hybrid transmission (DHT), elaborates on the working principle and lubrication performance requirements of dedicated hybrid transmission, conducts systematic research on different lubrication performance compared to transmission transmission transmission, and finally provides lubrication solutions. It also briefly describes the development and validation of oil products for dedicated hybrid transmission.

Aiming at the counterbalance force required to overcome the stall under gravity and the waste of gravitational potential energy of large hydraulic press using servo motor, an energy recovery device is proposed to compensate the driving torque of servo motor. This device, combined with corresponding circuits and accumulators, significantly reduces motor energy consumption. The energy-saving effect of this device and its structural design and operational characteristics are initially estimated under specific application environments and operating parameters. This provides valuable reference for selecting appropriate power startup and energy recovery schemes in large hydraulic presses.

The pump turbine of a pumped storage power station in China was used as a model for research, and according to its “S” characteristics, the movable guide vane airfoil was changed and assembled in the original water guide mechanism with different arrangement methods, and the influence of the change of the movable guide vane airfoil on the “S” characteristics of the pump turbine and the influence of the guide vane force characteristics were analyzed through numerical simulation based on the SST k-ω model. The results show that changing the airfoil of the guide vanes can effectively destroy the high-speed water ring between the active guide vanes and the impeller, reduce the obstruction of fluid flow into the impeller, and improve the flow state in the impeller area, and at the same time, the change of the movable guide vane airfoil also improves the radial force of the guide vane, and the peak-to-valley difference of the radial force becomes smaller after adding the modified movable guide vane, which has a good impact on the operation stability of the unit.

Jacking operation is a commonly used rescue method for high-speed trains in general derailment accidents. The hydraulic lifting equipment for the top lifting operation is the key technology, and the hydraulic cylinder is the main supporting equipment. To solve the problems of heavy weight and inconvenient carrying of hydraulic cylinders in railway rescue equipment, a double acting multi-stage titanium/aluminum composite oil cylinder has been designed. On the premise of ensuring the safety of the oil cylinder, a comparison was made on the weight of the original oil cylinder. It was found that the weight of the titanium/aluminum composite oil cylinder body decreased from 29.5 kg to 21.9 kg, with a weight reduction of up to 25.7%. Moreover, the stress distribution, material utilization, corrosion resistance, and wear resistance of the oil cylinder were all better than those of pure titanium alloy oil cylinders. The lightweight development of hydraulic cylinders not only improves the convenience and efficiency of railway rescue, but also opens up new perspectives for the design and manufacturing level of hydraulic cylinders, which is more in line with market demand.

Pneumatic shift system is used to reduce the driver's shifting force and improve the vehicle's shifting smoothness, which is an important link to improve vehicle safety. The existing pneumatic shift system has many problems, such as multiple pneumatic failures, poor man-machine coupling and low gear shift control precision. In the process of shifting, it is easy to have the shift stick and dislocation caused by man-machine confrontation, which leads to the shift failure and even leads to serious driving accidents. This paper analyzes the research status of pneumatic shift system fault diagnosis and pneumatic shift control system at home and abroad, and points out the existing problems and future development trends in the fault diagnosis ability of pneumatic shift system, compliance and flexible control of pneumatic shift system, which provides reference for the development of efficient pneumatic shift control system and real-time fault diagnosis technology.

The transient flow characteristics of an aviation micro plug-in relief valve are studied using CFD simulation technology. The research focuses on analyzing the fluid flow characteristics and spool motion characteristics during the valve opening process, including spool displacement, hydrodynamic forces, and transient pressure changes in the flow field. Dynamic grid technology is employed to divide the computational domain around the valve orifice with complex structure, considering grid migration and deformation caused by spool movement. Additionally, experimental studies are conducted to validate the accuracy of the simulation results at a product level. The experimental results show that the established CFD model exhibited good agreement with the start-up pressure-flow characteristic curves obtained from the tests, with a maximum error within 4.72%. Thus, the simulation model demonstrates a certain level of accuracy. The simulation results indicate that during the valve opening process, the researched relief valve has an opening pressure of approximately 26.1 MPa and a maximum flow rate of 22 L/min, displaying favorable flow and pressure characteristics. Furthermore, the valve exhibites rapid opening, minimal pressure fluctuations, and excellent opening performance. The stiffness of the spring has a certain influence on the opening performance, and the increase of stiffness will lead to the increase of the required opening pressure. Thus, it is necessary to strictly control this parameter in the machining process to ensure that the product meets the requirements of the opening performance.

Pneumatic valves are common pneumatic components that play a role in changing the direction of the airflow within the pneumatic system and are widely used in automated equipment, commercial vehicles, and medical devices. One important performance index of the pneumatic valve is flow rate. This paper takes a two position four-way solenoid valve as an example to carry out the design calculations for flow rate, structural calculations, flow simulation, and experimental verification, summarizing a general design process for the flow rate of pneumatic valves.