On the stern tube sealing, it has been required the longer durability as one of the sealing performance in order to sail without any trouble for the long time. It is understood the temperature at the contact of sealing ring and liner is mostly affected to the durability of this type of sealing system. Then, keeping an eye on the above temperatures, the authors have theoretically analysed and estimated the temperature at the contact as accurately as possible based on the measured data.
As a result, the influences of circumferential velocity of the liner and differential pressure to the temperature at the contact of sealing ring and liner were made clear quantitatively.
Furthermore the charts of permissible endurance limit on sealing ring were made based on the above results, and this has become valuable when the service condition of the stern tube sealing (Compact Seal) has been determined.

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Stork-Werkspoor Diesel B.V., Amsterdam completed a 6 cylinder in-line prototype of new medium speed diesel engine TM-620 and started its test-run in November 1975. The initial engine performance has already reached 1, 700 BHP/cylinder rating level at speed 428 r.p.m., BMEP 18 Kg/cm²on the prototype engine against 2, 000 BHP/cylinder of potential future ratings.
The new TM-620 engine design was based on their experience gained from existing TM-410 engine in principle, 380 sets of which have been sold and 250 sets of which are in service.
The TM-620 engine is virtually a scale-up of TM-410, in order to obtain the optimal engine range and the maximum sales volume.
In order to obtain good reliability and low maintenance cost including oil consumption for the use of heavy fuel as well as reasonable manufacturing cost, a frame design of both engine types is consisting of two heavy iron castings with sufficient rigidity, a U-shape bedplate and cylinder block, connected by means of two rows of tie-rods and careful cooling system and double wall construction or“Strong back”design are adopted to avoid increase of thermal stresses in combustion system.
The manufacturer is expecting that the new large medium speed engine TM-620 can offer more economical propulsion installation by well meshing link with TM-410 for all ship types.

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Referred to the equivalent turbine-propeller shafting with a mass at the thrust block joined to the supposedly rigid double bottom through a spring and also to another mass at the propeller through another spring, (1) the equation of the fundamental axial natural frequency is confirmed in order to correct a false equation written in two Japanese books, and (2) the frequency is calculated and compared with the measured one for a shafting shown in the paper by Rigby and also for five shaftings shown in the paper by Couchman so as to justify a more reliable description of the equivalent system than those given in three Japanese books.

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As a burner for boiler equipped on the L.N.G. carrier, the gas/oil combined burners having some special performances are needed in respect of the operating conditions.
The firing test was carried out by use of Chugai Ro-Hamworthy HXG burner which has been developed for a long period of time in order to be furnished with the above-mentioned special performances.
Burner performances investigated in the test are as follows:
1) Minimum excess air ratio.
2) Variations of flame length against gas-oil firing ratio.
3) Stability of oil flame under such burner operating conditions as ignition and shutting-off of fuel gas.
4) Relation between the blowing volume of N₂gas and stability of flame.
5) Temperature of gas nozzle tip under each operating condition.
6) Variations of register draught loss against gas-oil firing ratio.
The results of the test are shown concretely on the tables and figures for the convenience of designing the combustion equipment for L.N.G. carrier.

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In this paper two basic ideas of M.A.N. are shown. The first theme is“Definition of Power”. If it is said that an engine has 10000 PS, what does it mean? In addition to ISO-3046-Definition we need some special rulings for marine diesel engines. M.A.N. proposes two points.
a) Standard ambient conditions should be
air temperature 318°K (45°C)
sea water temperature 305°K (32°C)
air pressure 1 bar
b) Engine performance should be shown with performance field and not only with some particular points such as MCR or SR.
The second theme is“criteria in further development of marine propulsion systems”. The problems of heavy duty oils and two-stage turbo-charging are also discussed.

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This is a short description of recent development results and their effect on the sales programme. It includes also explanations of some basic ideas, aims, methods and results which apply to M.A.N. engines in particular and are the basis at all major development activities.
Within M.A.N.'s extensive engine programme efficient low-cost development is only possible if development is concentrated on essential part-assemblies and functions. Application to the engine, particularly application to the cylinder dimensions necessitates further matching but is only of secondary significance.
This principle permits systematic work by use of the latest calculation processes and measuring methods.
It is also ensured that the engine programme is standardized where the design and configuration of components and systems are concerned.
With this system it is even expedient and advisable to apply the experience gained with two-stroke engines to four-stroke engines and vice versa.

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