Abstract: Based on a custom-built experimental apparatus, the transmission synchronizer experiment is performed to analyze the failure process and failure mechanism of transmission synchronizer. During the experiment, the rotate speed of cone, the shift of sleeve, the moment of friction with shift time, and the friction coefficient as a function of shift number are obtained. After experiment, the surfaces of friction material are analyzed by scanning electronic microscope (SEM) and the non-contact surface profiler MicroXAMTM respectively, and the Fe content contained in lubricating oil is measured by atomic emission spectrometry. The results indicated that the friction coefficient goes down with the number of shifts, which led to the reduction of the acceleration and the increment of the synchronization time. The synchronizer becomes invalid because of low friction coefficient. During the shift process, the asperities of surface are worn, which makes the oil film rupture difficultly. The proportion of solid friction coefficient continues to reduce and the oil film friction coefficient occupies the dominance gradually, which is the main cause to induce the reduction of friction coefficient.

Key words: transmission synchronizer;failure process;failure mechanism