Gear Box as a high-speed train to transmit torque, driving the vehicle moving the key components, the safety and stability of the direct impact of EMU vehicle operation reliability. However, due to the complexity of its structure and its operating conditions are relatively poor, Gear Box system in recent years, many failures, such as oil leakage (oil), oil temperature is too high, bearing pitting, box cracks and so on. These problems have seriously affected the operation of high-speed train safety.

The main function of the gear box box is to support and contain the normal operation of the transmission parts, vibration, noise reduction, as shown in Figure 2-3. High-speed gear box box is characterized by dynamic load, the impact of large, high degree of integration, to withstand the outside world, the structure of complex and compact, light weight, heavy heat, heavy temperature, high temperature, seriously affecting the gear and bearing life , How to effectively handle the above problems is to improve the performance of Gear Box and the life of the key.

Gear Box as the main transmission components of wind turbines, in the event of failure and the need for maintenance, the wind farm will have a certain impact on economic efficiency. The wind turbine gear box lubricating oil for the operation of the gear box plays a vital role.

The Gear Box is the role of matching speed and transmission torque between the prime mover and the working machine. Therefore, the normal operation of the gear box affects the normal operation of the whole system, and its various aspects of the characteristics are also important. At present, the domestic production of mechanical products with foreign machinery products, there are still gaps, these gaps are mainly reflected in the basic components, such as hydraulic components, large capacity and low performance, serious leakage of oil. While the introduction of foreign mechanical products, the quality of the hydraulic system is more stable, after a long period of use of small oil leakage. Because of the importance of mechanical products and production process of cleanliness caused by poor quality, low product delivery rate, short life and other issues. Domestic introduction of foreign advanced technology at the same time, not on the product processing and assembly process cleanliness caused enough attention, resulting in the same technology, but the performance of the product produced with a lot of difference from abroad. The cleanliness of the gear box is mainly reflected in the parts in the process of assembly and assembly of iron and other impurities, lubricating oil cleanliness and other issues. The cleanliness problem is simple, but the problems or failures are multifaceted. The following is a description of the reasons for the cleanliness, the impact and improvement.

Gear Box of the various types of failures in the time domain waveforms have typical characteristics, from the time domain waveform analysis, you can generally get three aspects of fault information, that is, the type of time domain function (deterministic or random), the frequency component Whether the complex; vibration amplitude changes, changes in the law; whether the obvious impact of the waveform and modulation components. And the time domain eigenvalue analysis provides a quantitative reference for fault diagnosis. Therefore, by means of time domain analysis can be carried out on whether the failure of intuitive preliminary judgment. But to accurately determine the nature of the gear box failure, degree, location and reasons, need to use spectrum analysis, demodulation analysis, refinement spectrum analysis and other methods.

In fact, due to the frequency of vibration generated by the frequency of the modulation of the meshing frequency, so by the side band of the center frequency, edge band presented in the form and interval analysis of the line, the fault can exist and its parts to make judgments.

Many mechanical equipment in the fault with the operation, must be accompanied by the occurrence of vibration and shock, on the contrary, the occurrence of vibration and shock often reflect the mechanical failure. So the current fault diagnosis methods are mostly based on vibration theory. Resonance demodulation technology is the new development of vibration analysis method.