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In herringbone gears transmission, the pinion generally adopts the axial floating installation through the axial movement to realize the balance of axial force at both ends, which is called the load-sharing phenomenon. Load-sharing is an important characteristic of herringbone gears transmission, the essence of load-sharing analysis is the calculation of axial displacement at low rotation speed. The axial displacement at low rotation speed periodically changes with the tooth meshing (tooth frequency) and shaft rotation (shaft frequency), which is one of the excitation of the system vibration at high speed. However, it is not considered in the current dynamic characteristics study of herringbone gears. Therefore, the axial displacement under low rotation speed is calculated and is treaded as a kind of error excitation to put in the dynamic model of herringbone gears in this paper. Further, the impact of load-sharing on dynamic characteristics of herringbone gears is studied and the results show that the displacement, velocity, and acceleration in direction of bending, torsion, and axial all have changed, the maximum variation is up to 81,651% while considering the axial displacement. Therefore, the impact of load-sharing should not be ignored in the dynamic characteristics analysis, especially for the accurate analysis of dynamic characteristics for herringbone gears. The study enriches the theory of dynamic characteristic analysis of herringbone gears. [ABSTRACT FROM AUTHOR]

Taking a herringbone gear transmission system with star gear train as the research object and based on the finite node method，a system-level dynamics model considering shaft-bearing-rigid rotor and the meshing of gears is established. The dynamic characteristics of the system are analyzed based on the RMS of vibration velocity at the bearings with the rotation speeds. Then the theoretical analysis results are compared with the experimental data to verify the reliability of the proposed model. After that，based on the analysis of vibration characteristics and modal characteristics of the gear system，resonance localization and resonance cause analysis are carried out. The results show that the theoretical analysis is in good agreement with experimental results. This study provides a valuable reference method for resonance prediction and resonance cause analysis of herringbone gear transmission system of star gear train.

The Eulerian-Eulerian method is used to numerically simulate herringbone teeth using the precision machining technique of abrasive flow. The effects of inlet velocity and abrasive concentration factors on abrasive flow machining are investigated separately for numerical analysis to reveal the effects of dynamic pressure and wall shear on abrasive flow machining under different machining parameters. The simulation results show that increasing the inlet velocity can improve the processing efficiency and the processing effect of abrasive flow processing. Increasing the abrasive concentration increases the processing cost and predicts a weakening of the abrasive flow, allowing for the use of lower concentrations of abrasive flow for actual processing. [ABSTRACT FROM AUTHOR]

Due to the symmetrical flank configuration, herringbone gears have no resulting axial forces and a smaller tooth width than helical gears. Because of existing manufacturing limitations, currently only double helical gears with wide center space or assembled herringbone gears are applied. In the present work, a novel machining method for herringbone gears by power skiving is presented. For this purpose, tool and technology are designed using a mathematical process model and tested subsequently. It is shown that the process can produce the required geometry with significant improvements on productivity and accuracy. Additionally, the unused center area can be eliminated. [ABSTRACT FROM AUTHOR]

To study the load distribution mechanism of the power-split transmission, and improve the carrying capacity of the herringbone star gear transmission system, the dynamic model of the planetary gear system for a geared turbofan engine with the flexible pin was established based on the node finite element method. The model considered the comprehensive influence of meshing error, time-varying meshing stiffness, bearing supporting stiffness and meshing phase. The dynamic load sharing performance of the system were studied in the equivalent meshing error, and the influence of the error incentives and structure of pins on the load sharing characteristics was analyzed. The results indicate that the vibration track of the center gears deviates from the origin because of the eccentricity error. The load sharing performance of the system can be improved by improving gears' manufacturing precision. Moreover, the influence of manufacturing errors is larger than that of assembling errors. The flexible pin improved by Montestruc has the best load sharing performance among the four types of pin models designed in the study. The load sharing performance declines with an increase of in input speed and a decrease in input power. [ABSTRACT FROM AUTHOR]

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• Crack initiation life model of herringbone gear is proposed by critical plane method. • Centring error and angular misalignment sharply reduce the crack initiation life. • Moderate tip relief can eliminate stress concentration and extend the gear life. • Angular adjustment balances the load in centring error gears, improving gear life. The effects of centring error and angular misalignment on crack initiation life in herringbone gears are investigated in this work. Herringbone gears with centring error or angular misalignment are modelled for contact analysis. A crack initiation life model of standard and error gears is proposed in accordance with tooth stress history and a critical plane method for nonproportional loading. Then, the effects of centring error and angular misalignment on crack initiation life in herringbone gears are investigated. Results show that centring error and angular misalignment sharply reduce crack initiation life, but a moderate tip relief can eliminate stress concentration and extend crack initiation life. Furthermore, angular adjustment balances the load distribution of the left and right teeth in herringbone gears with centring error, improving tooth crack initiation life. [ABSTRACT FROM AUTHOR]