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34 THE SULZER-DIESEL REVERSI- BLE COMBUSTION MARINE ENGINE. We here give an illustration of the reversible Sulzer-Diesel marine engine of 100 H. P. exhibited in the section for marine and river transports of the Milan Exhibition, 1906. . The excellent results which have been obtained with station- ary internal combustion engines have made it desirable to introduce same for ship propuls'on purposes. Typical ma- TAE Marine REVIEW ers and gas producers. The engine room may thus be one-third smaller than for steam plants. Again, when the engine does not work, no stand-by losses need be taken into account. 'Among the oil engines it is claimed that the Diesel engine excels by using heavy and cheap mineral oils or res- idues'which cannot be utilized in other engines. The liquid fuel is supplied di- rectly by the combustion cylinder, where it is ignited by means of highly com- SULZER-DIESEL REVERSIBLE COMBUSTION MARINE' ENGINE. rine engines with the propeller direct- coupled to the engine and which can be reversed and controlled like a marine steam engine have, however, so far not been heard of. engines are far ahead of the steam en- gines with regard to fuel consumption. For the same output the weight of fuel is, in the case of gas and oil engines, _ one-third to one-half, and in the case of the Diesel engines one-fourth to one- sixth of what it would be for steam en- gines; The combustion of the fuel in the cylinders. of internal combustion en- gines can be made so complete that the exhaust gases are practically invisible, a great point, especially for the navy, where the smoke when running the steam engine under heavy overloads must be considered as a great disadvantage. A further advantage is the easy and speedy way in which the liquid fuel can be taken on board by means of centrifugal pumps or compressed air, likewise the transport from the tanks to the engines by the same means is as simple and clean as possible. The liquid fuel can be stored: in ballast tanks or between double bottoms. Besides the reduction in weight and space required for the liquid fuel as against coal, the weight taken up by the machinery is consider- ably less, owing to the absence of boil- Further, the combustion © _ engines, pressed air of high temperature. The ' quantity of fuel required to give a cer- tain output can be exactly regulated, which is not the case with suction gas plants. If the fuel supply to, the cyl- inder has once been adjusted, it is quite independent of the engine driver, and in no way affected by the temperature of a gas producer or a carburetter, The reliability of the ignition., as en- sured through the compression "taking place regularly in the working cylinder itself, whereas in the internal combus- tion engines" it? 'is "effected by means of electrical 'of 'tube ignition. Further, there is no sudden ificrease of pressure during the ignition" period the com- bustion takes place nlf constant pressure, and as the compressed air and liquid fuel are taken to the cylinders sepa- rately premature ignition is avoided and the reliability of the engine considera- bly increased. The flashing point of the Diesel engine fuel is so high that danger from explosion or fire need not be taken into consideration, nor are there any poisonous gases, as, for in- stance, in the case of gas producers. Again, the combustion in the Diesel en- gine is so complete that it is not neces- sary to examine the cylinders, pistons and valves. There are said to be Diesel which under varying loads have been working for weeks without stopping, and w:th the even loads under which marine engines work no difficulty is expected from this quarter. One great advantage of the Diesel én- gine is its constant readiness. It. can easily be started up in two or three min- utes without any preliminary manipula- tions being required. So far the Diesel engine has mostly been built as a four-stroke engine, con- sequently its cylinder dimensions are considerably larger than those of a double acting steam engine of the same output. The comparison does, however, not come out quite as unfavorable for the Diesel engine as at first sight one might be led to believe. The average indicated pressure in the Diesel engine is about twice as high as in a- modern steam engine, and even taking into con- sideration the ten or twelve per cent higher efficiency of the double acting steam engine (against the four-stroke engine) the average effective pressures are still higher for the latter (1.8 against 1). For the same speeds the respective cylinder volumes work out at 1: jj; = about 1:24. The Diesel engine can be built on the two-stroke principle and does not in any way imply reduced thermal or mechan- ical efficiency. Its cylinder volume is only about ten or fifteen per cent larger than for steam engines 'of the same out- put. Of course, the weight of the fly- wheel of the internal combustion engine must be added, but this, again, is con- siderably smaller for the two than for the four-stroke engine. The dimensions of the connecting rod, the shaft and frames are greater for' Diesel engines than for steam engines, the combustion pressure being higher than the corresponding initial steam pressure. But even allowing for this, as well as for the weights of the injection and starting vessels, the total weight of the Diesel engine equipment is considerably smaller, owing to the absence of the condensing and boiler plant, feed pumps, forced draft, and ash hoisting devices. In ships of the same dimensions and speed when driven by Diesel engines the advantages are: (1) reduction in the weight of machinery; (2) reduction in the weight of fuel; (3) reduction in the size of the engine room and tank rooms. : The result is that ships can he built with finer lines, which, again, re- duces the output required of the en- gines, or gives the ship a higher speed with lesser weight of the tanks, and with higher speed the radius of action can be considerably increased. To fully utilize all the above advan- tages, it is necessary to build the Diesel engines on similar lines as marine steam engines, that is to say, it must be made