The Engines of Dixie II, USA and Den [1908]

 

Engine of Dixie II

by Harry M. Crane

The engine of Dixie II was designed and built by the Crane & Whitman Company, of Bayonne, N. J., especially to meet the general plan for the boat as outlined by Mr. Clinton H. Crane, the designer of the hull; the more important requirements being that the engine should deliver 200 h.p. or more, and that it should not weigh more than 2,200 lb. complete. Both of these requirements were satisfactorily met.

It is probable that the success of the boat as a whole was due to the very close cooperation in designing and building the hull and steering gear.

The engine itself is of the so-called V-type, which has become rather familiar in the last few years in cases where light weight is of great importance. Roughly, it consists of two four-cylinder engines set at an angle of 90 degrees from each other, and 45 degrees from the horizontal; both engines operating a single four-throw crank-shaft.

The cylinders, which are of 7½ inches bore and stroke, are separate gray iron castings with integral heads, and water-jacketed for about three-quarters of their length. Very large rectangular openings were left in the water-jacket covers on account of lightness and to permit of holding the cores in casting. These openings were afterwards closed by thin bronze plate, fastened by machine screws.

Each cylinder is provided with three valves, — a main exhaust valve or port, which is uncovered by the piston at the end of the power stroke, and which resembles the exhaust stroke of a two-stroke engine; and inlet valve and a secondary exhaust valve both located in the cylinder head. The cylinder head is hemispherical and is machined all over on the inside. The inlet and exhaust valves in the head are set in one plane at right angles with the length of the engine, and at an angle of 30 degrees on each side of the center line of the cylinder. The valves are all operated from a single cam-shaft located in the upper corner of the crank-case. The main valve in the port is operated by a rocker arm inside the crank-case, while the inlet and exhaust valve on the cylinder head are operated by a single rocker arm pivoted above the head of the cylinder and operated by a push rod. A single cam works these two valves.

The exhaust valve is opened by the upward throw of the push rod, and the inlet valve by means of a heavy spiral spring which forces the push rod down into a depression in the cam, and is strong enough to overcome the spring which tends to close the inlet valve.

The crank-case is a single manganese-bronze casting upon which all the working parts of the engine are carried. The bottom of the crank-case, which is open, is closed by an aluminum oil pan. The crank-shaft, which as above stated, is of a four-throw type such as is used in four-cylinder, four-stroke engines, is carried on five Parsons' white brass bearings.

The connecting-rods from one set of four cylinders take hold directly upon the crank-pins by means of heavy boxes of the marine type; while the connecting-rods of the other four cylinders take hold on the outside of these boxes. Both of these bearings are Parsons' white brass lined.

The pistons are very light gray iron castings with two wide snap-rings on each, the piston heads being concave. The piston pins are hollow case-hardened steel, and are keyed and pinned into the pistons. They turn in phosphor bronze bushings in the upper ends of the connecting-rods.

The fly-wheel is a very light bronze casting, on the face of which is carried a ratchet starting device, operated through a chain and shaft from the after cockpit. To aid in starting, the compression can be relieved in all the cylinders by shifting the cam-shaft endwise.

The ignition is of the make-and-break low-tension type with storage battery and two coils to supply the current. Two Bosch magnetos are also provided, one magneto for each four cylinders; a single vaporizer supplies mixture to all eight cylinders. This vaporizer is a very simple form, consisting of a single gasolene jet in a comparatively small air inlet, and a secondary air inlet of larger size provided with a hand-controlled butterfly valve. The gasolene supply is controlled by a needle valve in the jet. In practice the needle valve is adjusted with the throttle and auxiliary air valves both wide open. This adjustment is practically a permanent one, all further control being obtained by the throttle and air valve only.

The engine is cooled by eight small plunger pumps, one to each cylinder driven from a single four-throw crank-shaft. The engine is oiled by a single gear pump, which forces oil into the main bearings, and through them into the hollow crank-shaft, which forces oil into the main bearings, and through them into the hollow crank-shaft and thence into the connecting-rod bearings. The oil thrown from the crank-shaft oils the cam-shaft and other mechanism in the crank-case, and then drains down into the oil pan and is circulated continuously by the pump.

In addition to this, the cylinder walls are oiled by two eight-feed Pederson oilers, driven off the water pump shaft, two leads being carried to each one of the eight cylinders.

The propeller shaft is driven from the engine through a combined reverse gear and clutch, which is carried out a bracket bolted to the after end of the crank-case. The after end of this bracket carries the go-ahead and reverse ball thrust bearings. The go-ahead clutch is a light cone clutch simply intended to pick up the propeller and to get it into motion. The final drive is through a four-armed jaw clutch which is absolutely positive.

The reverse gear is of the bevel gear planetary type, common in marine practice. It is operated by a contracting band on the outside of the drum, worked by a small foot pedal.

Steel was used in a number of parts, which in marine practice would have ordinarily been made of bronze.

Almost all the steel parts were made of an extremely fine quality of alloy steel, and practically all the parts so made were heat-treated in a manner suitable for the works to be performed.

Forgings were used in many places where castings would ordinarily be used in commercial work, even though a very much greater amount of machine work was required by this method of construction.

For about three weeks before the engine was finally installed, it was run in the shop under varying loads, including a run of about one hour and a quarter at full load, and it was thereby possible to get the bearings in the best condition and to make all the necessary adjustments. It also made it possible for those who were to operate the engine subsequently to become thoroughly familiar with its action under varying conditions.

It was this thorough testing that permitted Dixie II's running from Bayonne to Oyster Bay, a distance of 45 miles, at an average rate of 26 miles an hour, after having been run about twenty minutes in the waters of Newark Bay, after her launching, this short test being all that was necessary to make sure that the steering gear and general control of the boat were satisfactory.

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Engines In U.S.A.

The two engines in U.S.A., formerly Irene, driving twin screws, weigh 1,700 lb. The engines have dual unit gray iron cylinders of 8 inches bore and 7 inches stroke. The water-jackets are of spun copper, with driven steel hoop retention at the lower end.

The gray iron fly-wheels are 22 inches in diameter by 5 inches face and weigh each 108 lb. The crank-shafts are connected by solid jawed clutches to the screw shafts.

The ignition is two complete and separate jump-spark systems, one supplied by battery current and the other by Remy magneto.

The crank-shafts are nickel steel, 2½ inches diameter wrists and bearings. The valve ports are 3 inches diameter, valves same general construction as the Chadwick car-motor valves. The crank-box oil basin is partitioned so as to give each cylinder its own oil pit.

The rods are nickel-steel forgings, full marine type, four screws in each cap, bronze bush, not split on piston pin, and flanged half boxes, phosphor bronze, on the crank wrist.

The water circulation is by a bronze pump, radial sliding piston. The carbureter is Chadwick's own design, new, not yet patented, and not here described. All the gears are steel, case hardened, except the magneto pinion, which is laminated brass and fibre.

The oil is by Hill precision oiler.

In the boat these engines drive twin screws of Parsons' manganese bronze of 24 inches diameter and 44 inches pitch at a maximum speed of 850 r.p.m. The shafts are of nickel-chrome steel 1 15/16 inches diameter, with the exception of the bearings and key-seats, which are of larger diameter.

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Den's Engine

The general arrangement of Den's engine and controls contains several interesting features about which the designer, Mr. Charles Herreshoff writes as follows:

"The oil tank in the bottom of the engine has a water-jacket around it, and cold water is taken in the forward end and discharged from the after-end of the crank-case outboard, thereby keeping the lubrication oil in such condition that is assists in keeping all bearings and the center of the piston cool. In such long runs as Den has participated in, and in which she broke the record from New York to Poughkeepsie in an official race, held last year, the bearings all through the engine were hardly lukewarm, and so it has been in all of her races. This 72-h.p. engine has a bore of but 6 7/8 inches and a stroke of 5 3/4 inches, and runs in the boat at approximately 1,000 r.p.m. The reverse mechanism and steering column and all control levers are mounted upon two angle bars, and the engine may be taken out of the boat and put back inside of two hours. This has been demonstrated on several occasions. You will note that the time Den made at Huntington over the 30-mile course is considerably more than the time she made while racing on the Hudson, and when I handled her in the race against Dixie, in which she went over the 30-knot course in 1 hour and 15 minutes and some few seconds. I am quite confident that I could cover the 30-mile course with everything in good condition in 1 hour and 9 minutes. But it must be remembered that this engine in design is four years old, and it was used in the old Den with very varying success. The only trouble that we have had in the old Den with the engine was cylinder trouble, which was due to the inexperience of the foundrymen in this country and inability to deliver that kind of a casting which would stand up to the highest pressures which are possible to use in gasolene-engine construction. It was because I get a maximum amount of horse-power out of a given volume of cylinder at high speed that the strains of the cylinders are very high. However, by the introduction of 20% of steel into the iron, and with the addition of some silicon, I was able to get the cylinders to hold."

(Transcribed from The Rudder, Sep. 1908, pp. 120-123. )

[Thanks to Greg Calkins for help in preparing this page. — LF]