Abstract: The changes of physical and chemical tribological properties of two kinds of manual transmission oils before and after SSP180 synchronous durability test were evaluated by MRS-1J four-ball tester, SRV testing machine and EHD2 oil film thickness tester. The results indicated that the physcochemical properties of the sampes were basically unchanged before and after the test. The four-ball friction coefficient of the oils that can pass SSP180 synchronous durability bench test (100000 cycles)was kept at about 0.10, the SRV friction coefficient was kept at about 0.14, the maximum non seizing load, the four-ball mill spot diameter, the SRV horizontal, vertical, and average wear spot diameter had no obvious changes. The oil film thickness after durability test kept well with the increase of test speed. The four-ball friction coefficient and SRV friction coefficient of the oils that could not pass the SSP180 synchronous durability bench test decreased after the synchronous durability test and before the test. With the extension of the test time, the SRV friction coefficient of the two samples before and after the test decreased from 0.16 to 0.09 and 0.15 to 0.07, respectively. The stability of oil film, the size and stability of friction coefficient were the important factors that affect whether the oil could pass the ssp180 transmission synchronous durability test.

Key words: manual transmission fluid, synchronous durability, friction coefficient, wearscar diameter