The initial defects have greatly affected the gear transmission under harsh working conditions in the fields of wind power and ships. The influence of linear initial defects on the evolution of wear characteristics of helical gears was studied. The laser marking device was used to process the linear initial defect along the tooth width direction, and the gear without initial defect was used for comparison. It can be concluded that the linear initial defect changed the meshing state of the gear tooth, and greatly shortened the normal wear life of the gear, the normal wear life of the gear is shortened by about 45%, and the wear rate in the stable wear stage is increased by about 56%, a great deal of pitting corrosion and plastic flow on the tooth surface occurred in the pitch circle position of the defective gear. In addition, the lubrication condition deteriorated in the later period caused by lubricating oil pollution and the hard particles falling off the gearbox bearings entered the meshing surface and the emerged crack, which further accelerated the wear process of gear.

For sliding friction pairs formed by differential gears and gaskets, it is necessary to study the friction performance under the coupling of multiple working conditions (impact, vibration and alternating load). For example, it is of great significance to study the performance of sliding friction pair in the rear axle differential of truck and the friction and wear performance of the internal parts of aircraft and ships under the coupling condition of multiple working conditions, so as to obtain longer service life and excellent performance by improving the friction performance. The ball-disc pairs were experimentally built to simulate the friction and wear mechanism of materials under different types of dynamic loads. Under the condition of non-polluting white oil lubrication, increased the contact ratio of the pair, and made the pair reach the experimental state of no dynamic pressure lubrication, selected different types of dynamic loads (step load, damped harmonic excitation load (DHE), Short-term high load) loading method. During the experiment, force sensors and online visual ferromagnetic sensors were used to monitor friction and wear rate signals in real time, and TR200 profilometer and scanning electron microscope were used to observe and study friction characteristics. The results show that a reasonable step load can improve the friction and wear state of the ball-disk pair during the running-in period and reduce the peak wear of the surface contact portion of the pair of materials. The main wear form of the experimental pair under constant load and step load for plastic flow and squeezing deformation, the fatigue of the surface material is caused by the high frequency fluctuating load of DHE. Therefore, it is concluded that the step load has an effect on improving the friction and wear performance of the mating pair, and the DHE load has a damage effect on the mating pair.