The technology of applying fuzzy liability design to the harmonic gear drive was introduced, membership functions were determined, fuzzy reliability expressions were deduced, and performance function and standard deviation of various strength calculations were given. An example explains calculation process. The result shows that as a result of considering simultaneously the randomicity and fuzziness of variables, the fuzzy reliability is better than the general reliability under the same conditions.

Aiming at the lack of the studies of valve train system of diesel engine, an accurate four-mass dynamics model was established based on traditional single mass dynamics model. The gearing chain was separated from dynamics model and simplified to four independent centralized masses. The dynamics characteristics of the valve train system were calculated directly by numerical simulation. And it is indicated that the four-mass dynamics model has its own correctness and superiorities compared with single mass dynamics model.