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For better performance of outboard motors for high speed craft, improvement in the performance of the propeller strut located ahead of the propeller is indispensable in addition to ameliorating the performance of the screw propeller itself. Thus, it is extremely important to reduce the drag of the propeller strut, which accounts for the predominant portion of the submerged parts of the motor and hull when the craft is running at high speed and to improve the propeller efficiency in the wake of the propeller strut. This paper, taking up two different shapes of the propeller strut, compares the performances of the propeller placed in the wake of the propeller strut in tank tests, and discusses the drag of the propeller strut. The two propeller strut shapes are that of a 70% scaled down model of the propeller strut SUZUKI's 200 PS outboard motor and its improved version.

The idle gear rattle of automobile manual transmissions in neutral position has been analyzed, and the mechanism of the excitation force synchronized with engine rotation has been clarified. Namely, the idle gear rattle occurs when the clutch disc spline backlash fluctuates by the off-center between the engine rotation and the transmission rotation, which results in a sudden change in the input shaft angular velocity. It is thus found that the larger become the off-center between the engine rotation and the transmission rotation, the maximum value of the clutch disc spline backlash, the angular velocity and angular acceleration of engine rotation, the greater becomes the excitation force of idle gear rattle.

The Joetsu Shinkansen line (super express railway), which runs through a heavy snowfall district, is installed with snow-melting systems whose function is to melt snow deposit on the track by sprinkling heated water over a total distance of 74km. Because of its long water path in these systems, delivery and return of the water takes a very long time, resulting in a time lag of the feedback control. In order to lessen this time lag, a control system using a feed forward algorithm has been developed and a system operation test has been carried out. It is found to be very promising as a snow-melting device from a view point of energy saving.