Chapter III, we will give a brief description of the two 850 horse-power

Diesel engines installed in the cargo vessel “M. S. Monte Penedo,” which were built by Sulzer Brothers of Winterthur, Switzerland. We are indebted to the _Motor Ship_, London, for the details.

The engines are of the two stroke cycle, single acting type, with four working cylinders, a double acting scavenging pump cylinder, and a three stage ignition compressor cylinder. The bore of the working cylinders is 18.8 inches, and the stroke 27 inches. While the crank case is of the enclosed type, there are two sets of covers which can be easily removed for inspection while the engine is running, for as the scavenging pump performs the work of the crank case of the ordinary two stroke cycle engine there is no need of a tight case to retain the compression.

The scavenging pump is mounted on one end of the engine and is driven from the crank-shaft, the cross-head of the pump forming one piece with the piston of the low pressure cylinder of the injection air cylinder. All of the compressor stages are water cooled and fitted with automatic valves. The double acting scavenging pump has a piston valve driven by a link motion for reversing it when the engine is reversed. The air enters the pump through the top valve chamber from a pipe leading into the engine room. The air discharges a pressure of about 3 pounds per square inch in a header that passes in front of all four working cylinders. By means of a valve the air entering the low pressure stage of the compressor can be taken either from the atmosphere or from the discharge of the scavenging pump; taking the air from the latter allows of a greater weight of air taken by the compressor and consequently a higher compression for use in emergencies.

As in the ordinary type of two stroke cycle engine, two independent sets of exhaust ports are used, one set being for the scavenging air and the other for the exhaust gases, both sets being at the end of the stroke as usual. The air inlet ports are divided into two groups, however, one group being controlled by the piston of the working cylinder, and the other group by an independent piston valve driven from the cam-shaft. Both sets of ports connect with the main scavenging air header. By means of the valve controlled ports it is possible to admit scavenging air even after the other ports are closed by the piston, which greatly increases the scavenging effect. With the air at 3 pounds pressure the air from the valve controlled ports throw the scavenging air to the top of the cylinder even after the exhaust ports are closed. This valve is provided with a reverse mechanism. A single cam is used for operating the fuel inlet valve and the air starting valve, and the reversal of the engine is obtained by turning the cam shaft through a small angle relative to the crank-shaft, which of course also reverses the lead of the fuel valve. Starting is accomplished by compressed air, with the air valve lever on the cam, and the fuel valve lever off. After turning through a few revolutions, the air valve levers are raised, and the fuel levers dropped back on the cams which results in the engine taking up its regular cycle.

By moving the tappet rod of the fuel valve out of or into a vertical position, the time of the fuel valve opening is regulated and the amount of air is controlled. This movement is normally performed by a compressed air motor, but in an emergency hand wheels may be used.

One of these serves to rotate the camshaft through the required angle in order to set the cams in the positions for astern or ahead running and also reverses the link motion of the scavenging pump valve by the rotation of shaft, as mentioned above. The other auxiliary motor operates the fuel and starting air valves by moving the small spindle longitudinally to bring the tappet lever of the air valve about the required cam for ahead or reverse and also lifts this or the fuel valve tappet rod off its cam, according as it is desired to run on fuel or air.

The spindle on which the valve levers are pivoted is in two parts, divided at the center. This is to allow two of the cylinders to run on air whilst the other two are running on fuel, and, as can be seen from the dial where the pointer indicates the position, in starting up, whether astern or ahead, first two cylinders are put on air, then four on air, next two on air and two on fuel, and finally all four on fuel. This allows very rapid attainment of full speed.

The amount of fuel entering each cylinder can be regulated separately by small hand wheels.

Below the fuel pumps are arranged three auxiliary pumps, two of these being oil pumps for the oil circulation, whilst the other is of the piston cooling water. On the left of the engine and driven in a similar manner from the cross-head by links are three other pumps, one for the circulating water and the other for the general water supply of the ship.

Lubrication for the cylinders is furnished by 8 small pumps, just above the water pumps, two oil pumps being provided for each cylinder. As the supply pipe is divided into two parts, the oil reaches the cylinder at four points in its circumference. Four oil pumps are provided for the air compressor.

Four steel columns are provided for the support of each cylinder in addition to the cast iron frame of the base, and by this means the explosion stresses are transmitted directly to the bed plate. The cast iron columns provide guide surfaces for the cross-head shoes. The guides are all water cooled.

(64) The M.A.N. Diesel Engine.

The Maschinenfabrik Augsburg-Nürnberg, A. G., a German firm have built some remarkably large Diesel engines both of the vertical and horizontal types. The peculiar merits of the horizontal type of Diesel engine of which the M.A.N. company are pioneers are still open to discussion at present, but there is no doubt but what this type will be the ultimate form of very large engines when certain alterations are made in the design.

In Fig. 69 is shown a 2,000 brake-horse-power horizontal M.A.N. Diesel engine of the four stroke cycle type which is installed at the Halle Municipal Electricity Works, Halle, Germany. It is of the double acting type with twin-tandem cylinders giving four working impulses per revolution. This engine was installed in addition to the six producer gas engines already in place to take the peak load of the station at different times during the day, the gas engines meeting the normal steady demand.

This firm has built many thousands of the vertical type of Diesel engine of all sizes, and has recently installed 13 engines of 4,500 brake horse-power for operating the Kreff tramways. The company is now building cylinders giving outputs of from 1,200 to 1,500 brake horse-power per cylinder, giving outputs of from 5,000 to 6,000 horse-power in tandem twin type engines. As will be seen from the cut, the horizontal Diesel engine is remarkably free from complicated valve gear.

(65) Mirlees-Diesel Engines.

The Mirlees-Diesel engine is built by the English firm, Mirlees, Bickerton and Day both for stationary and marine service. A generating plant consisting of two, 200 horse-power Mirlees engines direct connected to Siemens generators has been installed in the municipal plant at Dundalk as shown by Fig. 71. On test these units consumed 0.647 pounds of oil per horse-power at full load and 0.704 pounds per horse-power at half load with a regulation of 3.24 per cent from full load to no load. All of the engines built by this firm are of the four stroke cycle type.

(66) Willans-Diesel Engines.

The Willans-Diesel engines built by the Willans and Robinson Company of Rugby, England, are in sizes up to 400 brake horsepower, and run at speeds up to 250 revolutions per minute. They are all of the four stroke cycle type and are applied principally to the driving of electric generators. The cut shows one of the four, 280 horse-power units supplied to the Alranza Company and the Rosario Nitrate Works in South America.

Unlike the Mirlees engine, the Willans has an individual frame for each cylinder as in steam engine practice. Like the steam engine frame, the bottom is left open for the inspection of the connecting rod ends and the main bearings which is a most desirable feature. The air compressor and pumps are arranged in a most compact form at the left end of the crank-shaft from which the pipes may be seen issuing to the four cylinders. The valves and over head gear are of the conventional type, which, with the exception of a few minor details are the same as those on the recently developed Sulzer-Diesel. The individual grouping of the cylinder units has many desirable features and should, we believe, be more extensively copied.

(67) Installation and Consumption of Diesel Plant.

An English gas-electric station was completed at Egham, England, that is a good example of the changes that have been made recently in the electricity supply abroad, with Diesel power.

The generating plant comprises two 94 K. W. Diesel engines built by Mirrlees, Bickerton and Day, direct connected to single phase alternators generating at 2,000 volts. The exciters are direct connected to the main shaft, and the plant is capable of generating an overload of 10 per cent for two hours. Space has been left for the installation of two more units of a larger size.

The following fuel consumption was guaranteed for a load of unity power factor, and the official tests show slightly better figures than the guarantee.

Full load 0.68 lb. oil per K. W. H. Three-quarter load 0.72 lb. oil per K. W. H. Half load 0.79 lb. oil per K. W. H. Quarter load 1.15 lb. oil per K. W. H.

Particular attention has been given to the water supply for the jackets of the engines; the circulation being by two electrically driven, direct connected centrifugal pumps, one of which is a spare. A Little Company’s cooler has been installed, which consists of a horizontal cylindrical chamber, the lower part of which contains water. In the tank are arranged a number of concentric metal cylinders spaced about ¼-inch apart, and in several sections, that are carried on a slowly revolving shaft, driven from the fan shaft. The cylinders are all of the same length, and are open at both ends.

The lower half of the cylinders dips into the water in the casing, and as they revolve, a thin film of water on each side of the plate is carried into the upper portion of the casing where it meets a blast of cold air from the fan. The fan is driven from the circulating pumps, and passes the air through the chamber in a direction opposite to that of the water, baffles being placed so that correct circulation is maintained.

The small loss is made up by connecting the ball cock in the tanks with another tank charged from the works well by means of a self-starting rotary pump, electrically driven. Very little power is required for the pumps and cooler. Fuel oil is stored in a tank outside the building, the oil being supplied to the tanks from an oil wagon by means of a small hand pump.

Oil is taken from the tanks and forced into the engine room by a rotary pump, from which it enters two graduated tanks located in the roof of the station. The graduations on the tanks allow the consumption of oil to be carefully recorded by alternately filling and emptying the two auxiliary fuel tanks.

The entire building is electrically heated, and the kitchen of the flat above the station is equipped with an electric cooking-stove for the use of one of the engineers who make it his residence.

DIESEL HORSE-POWER FORMULA

P. A. Holliday, in the _Engineer_, derives a new formula for computing the horse-power of the four stroke cycle, single-acting engine. For each horse-power developed by these engines about 21,000 cubic inches of displacement is necessary, per minute.

D = Cylinder bore in inches. S = Stroke in inches. M.P.S. = Mean piston speed in feet per minute. R = Ratio of stroke to bore. N = Revolutions per minute, then √(B.H.P. × 2220) D = ———————————————— M.P.S.

6 M.P.S. Knowing the value of D, N = ———————— S

For high speed, low ratio (R), four stroke cycle engines, approximately 22,000 cubic inches displacement per minute is required.

√(2,330 B.H.P.) D = ——————————————— M.P.S.

In both formulae, the air compressor for fuel injection is included.

(32) Semi-Diesel Type Engine.

In the “Semi-Diesel” Type Engine the oil is injected into the cylinder at the point of greatest compression in the same manner as in the Diesel engine, and like the Diesel it compresses only pure air. In regard to the compression pressure, however, it stands midway between the pressure of the Diesel engine and that of the ordinary “aspirating” type oil engine, as the compression averages about 150 pounds per square inch. While this is a much higher pressure than that carried by the ordinary kerosene engine which compresses a mixture of kerosene vapor and air, it is not sufficiently high to ignite the oil spray by the increase in temperature due to the compression, but ignites the charge by means of a red hot bulb or plate placed in the combustion chamber.

This type of engine is built both in the two stroke and four stroke cycle types, the events occurring in the same order as in the two stroke and four stroke Diesel types, that is, pure air is drawn into the cylinder on the suction stroke (four stroke cycle) or is forced in at the beginning of the compression stroke (two stroke cycle), and is compressed in the combustion chamber. At the end of the compression stroke, the fuel is injected against the red hot bulb or plate by which the charge is ignited. Expansion follows on the working stroke after the fuel is cut off, and release occurs at the end of the stroke.

Fuel oil is supplied to the spray nozzles by a governor controlled pump having a variable stroke or by compressed air as in the Diesel engine, making the supply of fire proportional to the load. A separate pump is generally supplied for each cylinder, which is capable of developing a pressure of about 400 pounds per square inch. Several of the Semi-Diesel type engines have water sprayed into the cylinder for the purpose of cooling the cylinder and piston, and as an aid in the combustion. This water spray increases the output of a given size cylinder by the amount of the steam formed by the heat of the cylinder and piston walls, and by the increased rate of combustion. The amount of water supplied to the cylinder is equal, approximately to the amount of fuel oil. The water connection is made in the air intake pipe so that the water spray and the intake air are drawn into the cylinder at the same time.

There is very little difference in the efficiency of the Diesel and Semi-Diesel in favor of the true Diesel type for both have accomplished records of a brake horse-power hour on .45 pound of crude oil in units of the same capacity. Neglecting the question of efficiency the Semi-Diesel has many advantages which are due principally to the differences in compression pressures. Valve and piston perfection in regard to leakage is not as essential with the semi-type as with the Diesel, as the former is not dependent on compression for its ignition. This means that the Semi-Diesel has a lower first cost and a lower maintenance expense. Its low compression pressure makes starting possible without the use of compressed air with engines of a considerable horse-power. As the explosion pressure is much lower than with the Diesel type there is less strain on the working parts and lubrication is much more easily performed.

Compared with the ordinary type of kerosene engine the Semi-Diesel is much more positive in its action as the oil is sure to ignite when sprayed on the hot surface of the bulb or plate when under the comparatively high compression. In the engine where the air is mixed with the vaporized fuel before it is drawn into the cylinder, it is difficult to obtain perfect combustion because of the uncertain mixtures obtained on varying loads by the throttling method of governing. At light loads the only difficulty encountered with the Semi-Diesel type is that of keeping the igniting surface hot enough to fire all of the charges.

In the majority of cases the two stroke cycle type of Semi-Diesel engines compress the scavenging air in the crank chamber in the same way that a two stroke cycle gasoline motor performs the initial compression, although there are several makes that compress the air in an enlarged portion of the cylinder bore by what is known as a “trunk” piston. This initial compression determines the speed of the engine, the pressure limiting the time in which the air traverses the cylinder bore and sweeps out the burnt gases of the previous explosion.

(68) De La Vergne Oil Engines.

Two types of four stroke cycle oil engines are built by the De La Vergne Machine Company, which differ principally in the method and period of injecting the fuel into the cylinder. While both types compress only pure air in the working cylinder, the oil is injected in a heated vaporizer during the suction stroke in the smaller engine (type HA), and is injected directly into the combustion chamber of the larger engine (type FH) at the point of greatest compression. This fuel timing classifies the type FH as a semi-Diesel, while type HA comes under the head of that class of engines known as aspirators.

Semi-Diesel (Type FH)

During the suction stroke, air is drawn into the cylinder through the inlet valve located on the top of the cylinder head, and on the return, or compression stroke, the air is compressed to about 300 pounds per square inch in the combustion chamber. The compression heats the air to a high temperature which is still further increased by contact with the hot walls of a cast iron vaporizer D, shown by Fig. 76-b. At the completion of the compression, the fuel is injected in a highly atomized state by compressed air through the spray nozzle F, the spray being thrown into the vaporizer.

The vapor formed by the contact of the spray with the walls of the vaporizer mixes with the compressed air in the combustion chamber and is ignited at the instant of fuel admission by the combined temperatures of the vaporizer and compression pressure.

As the fuel is not injected until the proper instant for ignition, it is possible to obtain a relatively high compression without danger of the charge preigniting. The oil is supplied to the nozzle by a fuel pump under pressure. The atomizing air takes the oil at pump pressure and performs the actual injection. Details of the spray valve are shown by Fig. 76, in which the oil and air are entered at a pressure of about 600 pounds per square inch.

The air and oil enter the nozzle at opposite sides of the cylinder B which fits snugly into the valve body A. As the air and oil proceed side by side along the outside of B, they are forced to pass through a series of chambers connected by a system of fine diagonal channels on the surface of B which results in a very fine subdivision and intimate mixture. The charge is admitted to the cylinder by a sort of needle valve about one-half inch in diameter which is provided with a spring that holds it closed on its seat as shown by C, in Fig. 76. The needle is so constructed that it may be readily removed at any time for inspection. The spray valve is located on the right hand side of the valve chamber directly opposite the vaporizer and is operated by an independent cam on the camshaft.

The vaporizer consists of an iron thimble having ribs on the inside to increase the radiating surface. In starting, the vaporizer is heated for a few moments until it reaches the temperature necessary for vaporizing the fuel, but after the engine is running, the blast lamp is removed and the temperature is maintained by the heat generated by the combustion of the successive charges. Since the fuel is ignited at the instant that it makes contact with the vaporizer, it is possible to accurately adjust the point of ignition by adjusting the position of the fuel cam on the camshaft.

Air for spraying the fuel is supplied by a two stage air compressor that is driven from the crankshaft by an eccentric. The air compressed by the first stage is stored in tanks at about 150 pounds pressure for starting the engine. The second stage compresses the air to about 600 pounds pressure, but is correspondingly small in volumetric capacity since it handles only enough air to spray the oil which amounts to about 2 per cent of the cylinder volume. A governor controlled butterfly valve in the air intake pipe regulates the amount of air taken in on the second stage to suit the varying charges of oil injected at each load.

In starting by compressed air, a quick opening lever operated valve on the cylinder head is used to admit air from the tanks to turn the engine over until the first explosion takes place. If the vaporizer is sufficiently heated by the torch, the explosion occurs during the first revolution of the crank shaft. At a point about 85 per cent of the expansion stroke, the exhaust valve is opened, and the products of combustion are expelled into the atmosphere. When starting, the compression may be relieved by shifting the starting lever from the exhaust cam to the auxiliary starting cam provided for that purpose.

Speed regulation is affected by a Hartung governor, driven from the camshaft, which actuates the oil supply pump through levers by shifting the point of contact between the pump levers and its actuating cam. This lengthens or shortens the stroke of the pump in accordance with the requirements of the load. The type FH engines are built in both single and twin cylinders ranging from 90 to 180 horse-power in the single cylinder type to 360 horse-power in the twin.

Since the fuel injection of the smaller engine type HA differs from that just described, it will be described separately in the following section.

The De La Vergne Oil Engine (Type HA)

In the small four stroke cycle De La Vergne Oil Engine, the fuel is injected into a heated vaporizer during the suction stroke in such a way that the vapor and intake air do not form a mixture in the cylinder proper. On the return stroke of the piston, the compression of the pure air takes place which forces the air into the vaporizer and into intimate contact with the oil vapor. This forms an explosive mixture which ignites and forces the piston outwardly on the working stroke. The release and scavenging are performed in a similar manner to that of a four stroke cycle gas engine. Both the inlet and exhaust valves are of the mechanically operated poppet type, and as both the inlet and exhaust gases pass through the same passage, the entering air is heated to a comparatively high temperature.

The injection pump receives the fuel from a constant level stand pipe or tank, located near the engine and injects the fuel into the vaporizer through a spray nozzle. The vaporizer is a bulb shaped vessel that is connected with the cylinder through a short post and really forms a part of the combustion chamber. Since no water jacket surrounds the vaporizer, it remains at a high temperature and vaporizes the oil at the instant of its injection. Because of the residual gases remaining in the chamber, ignition does not occur until air is forced through the passage by the compression. The air inlet valve and the fuel injection valve are opened at the same instant by a cam lever that also operates the pump.

On the compression stroke, the air which is at a pressure of approximately 75 pounds per square inch enters the vaporizer, and ignition occurs, partly because of the increased heat due to the compression and partly because of the supply of additional oxygen. Internal ribs provided in the vaporizer greatly increase the heat radiating surface and add to the thoroughness with which the atomized oil is vaporized. Since no mixture of air and fuel takes place in the cylinder proper, sudden changes in the load do not affect the ignition of the charge as the heated surfaces are surrounded with comparatively rich gas under all conditions.

Before the engine is started, the vaporizing chamber is heated to a dull red heat by means of a blast torch in order to vaporize the oil for the first stroke. As soon as the engine is running, the lamp is cut out and the temperature is maintained by the heat of the successive explosions. The combustion attained by this method is very complete even with the heaviest fuels, and whatever carbon deposit is formed occurs in the vaporizer from which it is easily removed. The contracted opening of the vaporizer passage effectually prevents the solid matter from working in the bore or valves.

A Porter-type fly ball governor maintains a constant speed at varying loads by regulating the quantity of fuel supply to the vaporizer, the air intake remaining constant. A by-pass valve, controlled by the governor divides the oil supplied by the pump, into two branches, one of which leads to the spray nozzle and the other to the supply tank. In the case where all of the oil is not supplied to the vaporizer because of a light load, the by-pass valve will return the surplus to the tank, thus maintaining a constant pressure at the spray nozzle.

When operating under ordinary loads, the governor opens only the small inside valve which regulates the amount of oil injected into the vaporizer. But should the engine speed up, due to a sudden change in the load, the governor will not only open the small valve but also the large concentric valve, in which case all of the oil will return to the tank. The makers guarantee the following speed variation limits under the different loads.

Ordinary Variation 2½ per cent. Full load to one-quarter load 4 per cent. Full load to no load 5 per cent.

(69) Operating Costs of the Semi-Diesel Type.

As the semi-Diesel type engine will operate successfully on the lowest grades of crude oils, with an efficiency that compares favorably with the true Diesel type, the operating expenses are very much lower than with the gas or gasoline engine. With the same fuels, the semi-Diesel will show greater net saving than the Diesel with a low load factor, as the fuel saving is not eaten up by the high first cost, and overhead charges of the true Diesel. Western crude oils with a specific gravity of .960 (16° Beaumé) are being used daily with this type of engine while nearly every builder of the semi-Diesel type will guarantee results with oils up to 18° Beaumé (.948 Specific Gravity). Fuel of this grade will cost anywhere from 1½ cents to 3½ cents per gallon in tank car lots, depending on the distance of the engine from the wells or refinery.

With fuel oil weighing 7½ pounds per gallon, an engine consuming .65 pounds per horse-power hour (a usual guarantee) at full load, the cost of a horse-power hour delivered at the shaft will be .26 cent with fuel at 3 cents per gallon. This the lowest fuel expense of any prime mover even with steam or gas units of great power. In a twenty-four hour test of a De La Vergne oil engine running on 19° Beaumé oil, the consumption was considerably below the figure assumed above, being .508 pounds per horse-power hour. Even the engine was exceeded in a test made on a 175 horse-power engine by Dr. Waldo, which gave a consumption of .347 pounds of oil per horse-power hour with oil of .86 Specific Gravity.

The following is a tabulation of reports received by the De La Vergne Machine Company from the Snead Iron Works, giving the cost of power at their plant under actual working conditions extending over a period of twenty-four months. The plant consisted of a 17 × 27½ inch De La Vergne semi-Diesel type engine of 180 horse-power rated capacity, the load factor being 54.2 per cent. The total power produced during the record was 552,217 horse-power hours, with a working period of 588 days. Fuel = 28.8° Beaumé = 7.35 pounds per gallon.

TABULATION

Items Total Cost Cost per Cost per K.W. Hour H.P. Hour Fuel Oil, 38,211 gallons $859.75 $.00232 $.00155 Lubricating Oil 228.72 .00061 .00041 Miscellaneous Stores and Repairs 123.20 .00032 .00022 Labor and Attendance 1361.42 .00368 .00246 ——————— ——————— ——————— Total $.00693 $.00464

Fuel oil used = .761 pounds per K. W. hour = .508 pounds per horse-power hour. Computing from the load factor of 54.2 per cent, the cost of power produced under the above conditions would be $9.30 per horse-power year, or $13.98 per kilowatt year. This result is obtained by assuming that the horse-power hours would be increased from 552,217 to 1,077,354, or in proportion to the actual load factor, the period, of course being the same in both cases.

(70) Elyria Semi-Diesel Type.

A type of semi-Diesel type oil engine has been recently developed by the Elyria Gas Power Co., Elyria, O., that presents many features of interest. It operates on the two stroke cycle principle, and with the exception of the spray nozzle has no valves in the working cylinder. The principle of the semi-Diesel type cycle as distinguished from the true Diesel engine, was described in Chapter III, as having the following characteristics. (1) Fuel injection. (2) Medium compression pressure. (3) Hot plate ignition. (4) An efficiency approximating that of the true Diesel type.

It is claimed that the change from the ordinary four stroke cycle Diesel cycle has been accomplished with practically no loss of thermal efficiency, and that the elimination of the many moving parts of that type has done away with many of the operating difficulties. By the introduction of a false piston end and an unjacketed cylinder head, the loss of efficiency due to the lower compression is compensated by the reduction of heat loss to the jacket water. Because of the high temperature it is possible to burn the heaviest fuels with a maximum pressure not exceeding 400 pounds per square inch, and without trouble due to missed ignition at light loads. With a given cylinder capacity this heating effect has increased the output about 75 per cent. The loss due to the friction of the scavenging apparatus causes a fuel consumption of approximately 10 percent more than a standard four stroke Diesel.

Unlike the Diesel, this engine automatically controls the quantity of injection air admitted to the cylinder at different loads, the air corresponding with the amount of fuel injected. This is in marked contrast with the Diesel engine which admits a constant volume of air at all loads. In place of the usual crank-case compression of the scavenging air met with in the ordinary two stroke cycle engine, the initial compression in the Elyria engine is performed by a “differential piston” which acts in an enlarged portion of the cylinder bore. This construction increases the volumetric efficiency from 70 percent, in the case of the marine type, to well over 90 percent, and it also does away with the bad effect of the compression on the lubrication of the main crank shaft bearings.

The working piston and differential piston as shown by Fig. 77 is separate castings fastened together by four studs, and the piston pin is carried by the differential piston which acts as a cross-head, taking all of the side thrust from the main piston. The working piston is easily taken from the cylinder by removing the cylinder head and the four nuts that fasten it to the differential piston casting. The displacement of the differential piston is approximately 1.9 times the displacement of the working piston which is more than enough for thoroughly scavenging the cylinder and supplying air for combustion. The air suction is controlled by a piston valve which eliminates much of the loss encountered in the marine type of two stroke cycle.

In the figure may be seen the separate or auxiliary piston head which is bolted to the piston proper, a construction that greatly increases the working temperature, and allows a symmetrical form of piston. By removing the cap over the inlet port, it is possible to inspect the condition of the six piston rings with removing the piston from the cylinder. Because of the clean burning of the fuel lubrication is easily effected by the force pump which supplies oil at three points around the cylinder wall.

Three stages of compression are employed for providing the air for fuel injection, the first stage being accomplished by the differential piston, and the remaining two stages by a separate air pump driven by an eccentric from the crankshaft. This cylinder also supplies the air for starting the engine, the air being taken from the second stage and piped to the storage tank. The suction of the second stage pump which receives its air from the differential pump (first stage) is controlled automatically so that it is possible to keep the supply tank at any desired pressure regardless of the pressure or amount of air used for the fuel injection. Air from the tank (at approximately 200 pounds pressure) is piped to the suction side of the third stage air pump. In this suction line is a valve, controlled by the governor, which regulates the amount of air admitted to the injection nozzle, and also the amount. This pressure at the nozzle will vary from 500 pounds per square inch to 1000 pounds depending on the load and the nature of the fuel. The high pressure air travels directly from the pump to the fuel valve casing, and is equipped with a safety valve and pressure gauge.

The fuel pump is driven by a Rites Inertia Governor located in the fly-wheel which varies the stroke of the pump plunger and gives a correct proportion of fuel to the load. This type of governor has been extensively used on high speed engines and is exceeding accurate. The fuel pump may be disconnected from the governor drive, and operated by hand when it is necessary to provide fuel for starting. The spray or injection valve is operated by a cam, which lifts the valve at the proper moment in a very simple manner. The valve proper is made of a single piece of steel with openings of ample size, so that there is no danger of clogging with the heaviest fuels. As the valve only lifts 1/16 of an inch, the amount of work required to operate the valve is very small.

Starting is accomplished by spraying cold gasoline into the cylinder through the fuel valve in the same manner that the heavier oil is fed during operation, and the ignition is performed by a high tension coil and batteries. No spark time device is used, so that a continuous shower of sparks is thrown into the mixture during the starting period. Within a minute after the engine is started, the ignition switch may be opened, the gasoline cut off, and the heavy oil turned on for continuous running on full load. Starting by an electric spark avoids the inconvenience and danger of torch starting with a retort.

Cooling water is admitted around the compressor cylinder from which point it goes to the working cylinder, and is there discharged. Less water is required for this type of engine than for the ordinary gasoline engine, for with the water entering at 60°F, only 3 gallons per horse-power hour is used. With fuel oil weighing 7.33 pounds per gallon the makers claim a fuel consumption of .65 pounds per horse-power at the rated load. The amount of cylinder oil used does not exceed 1 pint per 100 horse-power hours, while the loss of the bearing oil is extremely small because of the return system.

(71) Remington Oil Engine.

The Remington Oil Engine is a vertical oil engine operating on the three port, two stroke cycle, and is an oil engine in the strict meaning of the word, the oil consumed being introduced into the combustion chamber as a liquid and gasified within this chamber.

The method of gasifying and igniting the charge of oil in the Remington Oil Engine is unique. Only clean air unmixed with any charge, is taken into the crankcase. This air is afterwards passed up into the cylinder and compressed until its temperature has raised to a point high enough to vaporize the oil which is injected into it. The charge of oil is then atomized into this hot compressed air and turns immediately into a vapor, which finds itself well mixed with the charge of air, comes in contact with a firing pin recessed in the head, ignite and burns. This method of having the oil well gasified and mixed with air before ignition begins, prevents the formation of carbon which is formed when oil not well gasified and mixed with air comes suddenly in contact with very hot surfaces.

This perfect system of gasifying the oil has the effect not only of preventing the formation of carbon in the cylinder, but also of increasing the mean effective pressure and therefore decreasing the amount of fuel necessary for doing a certain amount of work. The engine passes through its cycle of operations smoothly, and does not have to be constructed with excessive weight.

The Remington Engine is of the valveless type, delivering a power impulse in each cylinder for each revolution of flywheel. The gases are moved in and out of the cylinder through ports uncovered by the movement of the piston, which itself performs also the function of a pump.

On the up stroke of the piston a partial vacuum is created in the enclosed crankcase, causing air to rush in when the bottom of the piston uncovers the inlet port seen directly under the exhaust port (23), Fig. 79. On the next down stroke this air is compressed in the crankcase to about four or five pounds pressure per square inch. Meanwhile the mixture of oil vapor and air already in the cylinder is burning and expanding. When the piston approaches the end of its down stroke, it uncovers the exhaust port (23), permitting the burnt charge to escape, until its pressure reaches that of the atmosphere. Directly afterward the transfer port on the opposite side of the cylinder is uncovered by the piston, thereby allowing a portion of the air compressed in the crankcase to rush into the cylinder, where it is deflected upwards by the shape of the top of the piston and caused to fill the cylinder, thereby expelling the remainder of the burnt charge. The piston now starts upward, compressing the fresh charge of air into the hot cylinder head. Near the end of the stroke, a small oil pump, mounted on the crankcase and controlled by the governor, injects the proper amount of oil through the nozzle (13), into the compressed and heated air.

This oil is atomized in a vertical direction through a hole near the end of the nozzle. It is therefore vaporized and gasified before there is a possibility of its reaching the cylinder walls.

The spray of oil is ignited by the nickel steel plug (12), which is kept red hot by the explosions because the iron walls surrounding it are protected from radiation by the hood (11). By the burning of the oil spray in the air the pressure is gradually increased and the piston forced downward, this being the power or impulse stroke. Near the end of the down stroke, the exhaust port is again uncovered and the burnt gases discharged.

The operations above described take place in the cylinder and crankcase with every revolution. Each upstroke of the piston draws fresh air into the crankcase and compresses the air transferred to the cylinder. Each down stroke is a power stroke, and at the same time compresses the air in the crankcase preparatory to transferring it to the cylinder by its own pressure at the end of the stroke.

The same volume of air enters the cylinder under all conditions, and the power is regulated by modifying the stroke of the oil pump, which may be done by hand or automatically by the governor in the flywheel. A separate fuel pump is provided for each cylinder when multiple cylinders are used, making it absolutely certain that each cylinder shall receive the same amount of fuel for a position of the control lever.

When starting the engine, the hollow cast iron prong rising from the cylinder head is heated by a kerosene torch, and when hot, a single charge of oil is admitted to the cylinder by working the hand pump. The flywheel is now turned backward, thereby compressing the charge which ignites the fuel before the piston reaches the highest position. After being started the engine, the torch may be extinguished.

The governor is of the centrifugal type. It has an L-shaped weight, pivoted to the piece attached to the flywheel. As the engine speed increases, the weight tends to swing outward toward the flywheel rim, and thereby moves the arm attached to it so as to shift the cam along the crankshaft toward the left.

This cam turns with the shaft, and operates the kerosene oil pump. According to the position of the cam on the shaft, it will impart to the pump plunger a long or a short stroke, thereby injecting more or less oil into the cylinder. The lever pivoted on the bracket moves with the cam and is used for controlling the engine’s speed by hand. To stop the engine the handle of the lever is pulled towards the flywheel, thereby interrupting the pump action altogether.

The handle of the control lever can be fitted with an adjustable speed regulator when required. This device is for use on marine engines to enable the operator to slow down the engine. The speed regulator does not interfere with the action of the governor but acts in conjunction with it. Whatever the speed of the engine may be, it is under the control of the governor. The engine can be controlled from the pilot house if such an arrangement is desirable.

The fuel pump is made of bronze. The valves are made of bronze and are designed with very large areas. The plunger is made of tool steel. A bronze cup strainer is attached to the lower end of the pump to prevent sediment or foreign matter from reaching the pump valves. As a result of the care used in its construction, the fuel pump is not only very sensitive in measuring the oil required by the governor, but is also very strong and durable.

The nozzle through which the fuel is atomized into the cylinder is thoroughly water jacketed to prevent the formation of carbon within the nozzle. It is so constructed that the water jacket spaces and fuel spaces can be opened for inspection.

Lubrication of all the important bearing joints is effected by a mechanical force feed oiler, pressure feed oiler or by gravity sight feed oilers, depending upon the service for which the engine is designed. Oil is fed in this manner to the piston, the main bearings and the crankpin bearings. The oil for the crankpin is dropped from a tube into an internally flanged ring attached to the crank by which it is carried by centrifugal force to a hole drilled diagonally through the crank and crankpin to the centre of the bearing. This insures that all the oil intended for the crankpin shall reach it. This feature, as well as the use of the sight feed oiler itself, is in line with the best modern high speed engine practice, and is an important factor in the reliability of the engine.