We have established a simulation platform for the machine–electro-hydraulic coupling system of the transmission system and the control system to study the root causes of the problems of large shifting impact and slow change of the machine tool transmission system. The dynamic analysis of the gear shift work of the gearbox was carried out, and the main factors affecting its shift instability were studied. With the impact and sliding power as the optimization goals, the shift quality is optimized based on the multi-objective genetic algorithm. Through the shift experiment, it was found that the power interruption phenomenon during the shift process was eliminated after optimization, and the quality of the shift was improved. Simulated planetary row wheel gear meshing force was found in the same gear, and the second planetary row gear meshing force was the largest among the planetary rows. The stress of the node near the top of the tooth is greater than the stress of the node near the node circle and the root of the tooth, and the two sides of the tooth top are relatively larger than the intermediate stress. The dynamic simulation model of the planetary gearbox system with rigid–soft hybrid can obtain the stress distribution of the solar wheel at the maximum impact moment and the stationary stage, as well as the dynamic stress of the key nodes of the solar wheel, which lays the foundation for the fatigue strength and life prediction of the gear system.

In this study, a nanofiber catalyst layer with high performance at low platinum loading was successfully prepared by electrospinning, and its structure and function were characterized by physical and electrochemical methods. The operating characteristics of the nanofiber catalyst layer under different temperature and humidity were determined. Under the same platinum loading conditions, the specific surface area of the nanofiber catalyst layer is 1.4 times that of the traditional catalyst layer, and the performance is also better. On the one hand, the nanofiber has a larger specific surface area, which provides more reactive sites for the catalyst layer; on the other hand, because the nanofiber catalyst layer has more pore structures, which is beneficial to the timely removal of water produced by the cathode And gas diffusion, thereby reducing the material transmission loss of the fuel cell at high current density. After adding hydrophilic SiO₂, the contact angle of the electrospinning catalyst layer is smaller than that of the electrosprayed catalyst layer, so it has certain self-humidification ability.

After the machine tool works continuously, the temperature of the hydraulic system continues to rise, which affects the work efficiency of the machine tool. Therefore, it is very important to control the temperature within a reasonable range. This paper proposes an improved scheme to replace a single fan with dual fans to improve the heat dissipation capacity of the radiator. Starting from the principle of heat exchange between oil and air, the relationship between the oil temperature and the wind speed on the face of the heat exchanger is derived, and the theoretical basis of the cooling system is given. Combined with logic control, the fan has the advantages of fast action, high efficiency and low energy consumption, which ensures the efficient and reliable operation of the machine tool. A one-dimensional simulation model of the thermal hydraulic system is established, and the heat generation and heat dissipation power of each element are calculated. Among them, the heat dissipation of the radiator is the largest, accounting for about 55% of the total heat dissipation. The experimental results show that the optimal fan speed is 3200 r/min and the flow rate is 0.2 m³/s at 26 °C. The thermal balance temperature of the hydraulic system is reduced from the original 65 °C to 58 °C, and its cooling capacity meets the requirements of a high-altitude and high-temperature environment.

The prominent problem of articulated steering structure of engineering vehicle is that there is pressure oscillation in the hydraulic system during steering, which seriously affects the performance of steering system. To solve this problem, the maximum stroke difference of left and right cylinders and the minimum maximum cylinder pressure are the optimization objectives, and the position of cylinder hinge point is the design variable. The multi-objective optimization design of articulated steering system is carried out by using the particle swarm optimization algorithm. After optimization, the maximum pressure of the steering system is reduced by 13.5%, and the oscillation amplitude is reduced by 16%, so the optimization effect is obvious. The dynamic characteristics of the hydraulic steering system under different loads, such as pressure and flow rate, are obtained through field steering tests of wheel loaders. The results show that the load has an important effect on the pressure response of the system, and the causes and influencing factors of pressure and flow fluctuation are determined. The relationship between mileage and hydrogen consumption is obtained, which provides data support for vehicle control strategy. The high-pressure overflow power consumption accounts for 60% of the total work, and the work lost on the steering gear reaches 36 kJ. The test results verify the rationality and correctness of the optimization method of steering mechanism and provide data support for the improvement in steering hydraulic system.