Steam turbine driven generating power plants have been of the main strength in electric power nets on land in these 30 years. However, the situation or condition is now changing, owing to circumstances of“Oil”.
In this paper, an establishment or a development of large electric generating power plants, founded on a new idea, which can be used not only in electric power nets on land but also in electric power plant barges and so on is proposed, in order to solve an electric power energy problem which is most important at present in the world economical problems.
The above electric power plants are based on the idea in which a plurality of diesel engines is combined with each other by a speed-up gearing in order to drive a large output power generator.
The feasibility of the above new power plants is largely dependent upon techniques which have been developed in fields of ship propulsion systems.
The special features of the above plants of the idea compared with steam turbine electric power plants having the same capacities are as follows:
(1) Costs of construction or building of the new plants are cheaper.
(2) Heat efficiencies of the new plants are higher.
(3) Practical differences of efficiencies between the said two plants become further larger, owing to features that the above new plants can easily be stopped through the night, and there are differences of efficiencies in partial load operation of the said two plants.

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The drastic increase in oil prices which began in 1973 resulted in the fuel oil consumption again becoming a major parameter for the operational economy of a ship. One of the best ways to achieve low fuel oil consumption is to reduce the required propulsive horse power by adopting a larger diameter propeller at lower revolutions having increased propeller efficiency.
The newly developed twin-bank engine gives the best solution to this purpose, utilizing a most reliable two-stroke, low-speed crosshead type diesel engine together with a conventional reduction gear so as to select suitable propeller revolutions in wide range keeping capability of burning lowgrade fuel oil. The twin-bank engine also enables to reduce engine room space requirements, and thus providing for increased space for cargo.
The specific fuel consumption of engine itself has attained to be cut down about 7% by introducing the constant pressure turbocharging to the uniflow scavenging system.

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From an energy saving viewpoint, an effective method to generate electricity for diesel ships is to recover the energy available from the exhaust gas of the main diesel engine.
So for turbo-generating plants driven by steam (7-8 kg/cm²g) which have been converted with an exhaust gas economizer have been used for this purpose.
However, when the rated-output of the main engine is less than 20, 000 BHP, this conventional system is not practical, i.e. the electric power obtainable cannot sufficiently meet the demands of the ship's plants due to the relatively small amount of exhaust gas energy available.
While, the need for saving energy has become more important following the energy crisis of 1973. In response to such social needs, Hitachi Zosen has developed a new turbo-generating plant which makes it possible to obtain the electric power needed on board even when only a relatively small amount of exhaust gas energy is available from the main diesel engine.
The main features of the new plant include a reduction in steam pressure, the addition of new heat recovery techniques and the application of newly developed compact steam turbine. Namely in each, the reduction in steam pressure allows increased heat recovery in the exhaust gas economizer by decreasing the saturated steam temperature and the heat recovery techniques aid in providing better steam evaporation and the compact steam turbine efficiently convert steam energy to electric power.
This new plant can be practically adopted for ships which have a main engine with roughly over 10, 000 BHP.

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For marine motors a lot of“F”class motors lately have been used instead of“E”class. This is a report of the results of our study on the recent problems on the protection against the general and special use motors and the specifications of starting transformers with reference of actual data.

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Among investigations made mainly by Mitsui to improve reliability and performance of Mitsui-B&W type engines, reports are made on the following items.
• crack on cylinder cover
• improved performance of cylinder liner
• improvement on exhaust valve
• crack on piston rod

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In 1976, Kawasaki Heavy Industries, Ltd. manufactured an Epicyclic Gears for Medium-speed Diesel Engine developing 18, 000 ps and made the first step for practical use.
In order to confirm the performance of the Epicyclic Gears, Shop Load Test and Sea Trial were carried out successfully, and stress at the roots of Annulus teeth and load sharing between the planet gears were measured during these testings in addition to general measurements, such as vibration, noise, torque and dynamical displacement of shafts and others.
In this thesis we report the results of above mentioned measurements and also estimate the Fatigue Life of Annulus teeth under expected operating condition of the ship.
The following results were obtained from these testings;
(1) Measured tooth stress in close to the value calculated by Lewis' equation considering stress concentration factor.
(2) Equalizing the load on each planet gear is considered good, because the obtained Load sharing factors are almost less than 1.05 and maximum value is around 1.10.
(3) Gear teeth are considered enough safe from the viewpoint of the Fatigue Life under expected operating condition of the ship.

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