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Gear transmission is widely used in mechanical transmission system and acts an important role in automotive industry. Manufacturing errors, assembly looseness, gear wear issues may result in gear backlash, noise and fatigue damage seriously affecting efficiency and service life of gear transmission. For gear transmission assembled, it is important to monitor the conditions of gear meshing and prevent the occurrence of dangerous situations. How to define the issues of gear tooth wear, misaligned bearing, gear eccentricity, backlash, and how to find faulty planetary gear sets and specific issues existing in gear transmission are meaningful and significant to ensure the quality of product. This paper starts from the analysis on gearing mechanism. Based on the behaviors represented by the issues, gear tooth wear, misaligned bearing, gear eccentricity and backlash are demonstrated and explained in detail.

Intake volumetric efficiency (VE) of a spark-ignition engine varies with valve timings, engine speeds, and manifold air loads. The existing approaches to reveal the underlying effects of these VE factors on instant valve flows remain complicated and expensive. In an effort to develop an applicable approach to analyze the detail valve flows, a naturally aspirated production engine with dual independent VVT was dynamometer-tested with fast in-cylinder pressure measurements and slow manifold pressure measurements. Both intake and exhaust valve flow was then reproduced using a new model, DQS model, in crank-angle resolution (CAR). One new flow mechanism, the flow wave subsidence, has been revealed to be one of the major drives of VE changes. We propose a dynamic quasi-steady (DQS) flow model to reproduce the valve flow profile from the measured pressure data. The DQS model features two manifold dynamics and a delay in the use of in-cylinder pressure measurements.