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In the development of a magnetic-coupling water pump, the pulling-out (disengagement) of a coupling that led to the stopping of an impeller was a concern. Upon analysis of the behavior of the magnetic coupling, presence of two types of the pulling-out was found, that is, the pulling-out resulting from a lack of transfer torque in the high-speed revolutions and the pulling-out due to the resonance of an inner magnet and an outer magnet. Main factors that affect the pulling-out are the angular velocity input to the drive side, the moment of inertia of the driven side, characteristics of the magnetic coupling, and a damping from coolant. Using a measurement and simulation of the behavior of the water pump, factors were analyzed and the process of pulling-out was clarified. As a result, design specifications that prevented the pulling-out were established.

In engines having an inline four cylinder DOHC configuration, the rotational vibrations of camshaft increase at high engine speeds above 10000 rpm, causing an increase of tension in the cam chain. It is therefore difficult to realize an optimum designing of a cam chain system when the durability has to be taken into considerations. Using the simulation we analyzed in this research how the rotational vibrations and tension increase at high engine speeds in an inline four cylinder DOHC engine. As its consequent, it is understood that the increases of rotational vibrations and tension caused by the resonance of the spring mass vibration system in which the cam chain serves as springs and the camshafts as the equivalent masses. Also it is found out that the vibration system is of a unique non-linear type in which the resonance of the fourth order frequency is also excited by the crankshaft torque fluctuations of the second order frequency.

A numerical calculation method, which enables the analysis of gear train behavior including non-linear elements in a motorcycle engine, was established. During the modeling process, it was confirmed that factors such as bearing distortion, radial bearing clearance and elastic deformation of a tooth flank could not be neglected because they effect the rotation behavior. To keep a high accuracy, those factors were included in the simulation model, after they were converted into the rigidity elements along the rotational direction of each gear model. In addition, the model was combined with a crankshaft behavior calculation model for a driving and excitation source. A time domain numerical integration method was used to perform the transient response simulation across a wide range of engine speeds. A jump phenomenon of response behavior of the driven gear was predicted that is a characteristic of non-linear response. The phenomenon was also observed in a physical test.