Marine propulsion engine with reduction gear has such merits that the engine becomes smaller in size and cheaper in price by increasing engine revolution, and as for the propeller, the revolution having the highest propulsive efficiency can be easily and voluntarily obtained by selecting a certain reduction ratio.
In spite of the fact that great benefits as above mentioned are given in case this engine is adopted in cargo or dredging ship, it has been rare to adopt geared diesel engine for such ship's except high speed diesel engine, for the reason that the diesel engine gives bad effects to the reduction gear by its large torque fluctuation. While, from several years on ward, our Yokohama Shipyard noticed of the utilization of the geared diesel engine having the aforesaid benefits and made the following design of it.
The feature of our design is that the reduction gear is coupled with diesel engine directly with allowable large fly wheel, which is the simplest and most effective system, and there is no slip of revolution between engine and reduction gear, compared with the case of using hydraulic or electric slip coupling.
One of the case is of the cargo sihp, “Matsuura Maru”, 3728 D. W. T, for the Mitsubishi Shipping Co., Ltd. The engine of this Ship is of 4 cycle single acting trunk piston with exhaust turbo charger (G 8 V 30/42, 513 rpm at 1200 PS) and is coupled with reduction gear with elastic sleeve spring “Hülsen” damper. The reduction ratio is 513/125 =4.1.
Each ship is now in service in satisfactory condition.
The utility of geared diesel engine was testified by its satisfactory operation and the analyzed value of measured torque fluctuation, which show the rightness and appropriateness of our design.
The photograph shows the pinion gear running in good condition. As a result of this test, it was proved that the measured torque fluctuation, was only 3%.