C. E. Spaulding.

It is the object of this article to furnish the reader with a design and description of a gasoline engine for light stationary use, in as few and plain words as possible, in order that every part of the work may be thoroughly understood.

The engine here described is of the two-cycle type ; that is, the working cycle is divided into two parts, getting an impulse at each revolution of the crank. The general working of this engine is as follows : The gasoline (which to give satisfactory results should be of the 74° quality) is fed from the tank to the vaporizer, where it is mixed with the proper amount of air and then drawn into the crank case by action of the piston on the upward stroke. It is compressed by the downward stroke, and, as piston uncovers the transfer or inlet port, the compressed charge is forced into the cylinder ;and again compressed by the upward stroke, and ignited by an electric spark when piston is nearly at top of stroke. The expansion of the ignited charge forces the piston downward, the burnt gases being expelled through the exhaust, which is uncovered by the piston in advance of the inlet port.

It would be well, perhaps, to divide this description under different headings and describe each separately, as follows:

The cylinder, cylinder case, cylinder head, governor, throttle valve, ignition mechanism, piston and piston rings.

The cylinder (as well as case, head, governor, piston, etc.) is made of cast iron, is bored and reamed 3" in diameter. The top and bottom are rough-turned to allow tight fit for cylinder head and bottom half of crank case. The port faces are also planed to allow for fitting of covers. The cylinder contains a water jacket, or space of 1/2" between outer and inner walls to allow for circulation of water. The reason for this can be better understood with a few words of explanation. The explosions in the cylinder vary from 100 to 500 per minute, so it can be readily seen that the heat to which the cylinder walls are subjected is very great. Should these walls reach a temperature above boiling point, the charge of gas would explode at the wrong moment, causing premature firing; therefore it is essential to use a circulation of water to keep the cylinder cool. It would be well to mention the fact that the boring of cylinder is the most important of all the machine work, as it is essential that the cylinder should be perfectly true and smooth. The cylinder contains two oblong openings, front and rear, to allow for use of tools in cutting ports to the required sizes. The inlet port has two openings, 1/2" by 1", and a 3/16" web in center. The exhaust port has two openings, 5/8" by 1", and also a 3/16" web in center. At the top of the cylinder are two bosses; one is drilled (3/8" in diam.), to allow for spark pin, while the other is tapped out with a 5/8"-20 thd. for bushing of igniter lever.

The cylinder case, while answering the purpose of a reservoir for gas, also performs another important function. There is placed in this case a sufficient amount of oil to cover the end of the connecting rod, which becomes lubricated by splashing in the oil. This is considered the best way of ensuring perfect lubrication of this part of the engine ; furthermore, it is the safest, as it takes no thought upon the part of the operator. In the side of case is a 1/8" pipe tap, for the drawing out the oil.

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Gas Engine.

The cylinder head needs but very little description. It contains a water jacket similar to the jacket in cylinder. Two holes are drilled through the face of head, to correspond with holes drilled in top of cylinder, into the jacket to allow for the circulation of water. It is just as important that the head should be kept cool as the cylinder, as the explosion takes place at this point. The cylinder head should be given a rough cut, as was specified in regard to the corresponding surface on the end of the cylinder. This is done to make the packing hold better and save blowing out. The head is tapped for 3/8" pipe for water outlet, and is fastened to cylinder by four 5/16" by 7/8" cap-screws.

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The above is a general description of the main parts of the engine; we will proceed with the finer and more important portions, drawings of which accompany this description. Before taking up the description of the governor it would be well to explain the construction and action of the throttle valve. The valve is turned to 3/4" diameter, and a corresponding hole is drilled in the transfer port, also tapped for bushing, to which a stuffing nut is attached. This valve, termed a "butterfly valve," controls the amount of gas to be admitted to inlet port. Attached to the lever arm of valve is a connection running to governor arm.

The governor comprises two weights, weight-bearing, collar, governor arm and arm-bearing, as shown in drawing. The governor weights are attached to the weight-bearing by means of 3/8" steel pins with split pins on each side, or with cap-screws with nuts. The bearing is fastened to the hub of the balance wheel. On the collar, which is bored out to a sliding fit on crank shaft, is cut a J" groove. When the weights are in their normal position, the nose of each rests in corresponding holes, which are cored in collar when casting is made. In the yoke of the governor lever are fastened two steel pins to fit in groove of collar. Fastened to the extension on the arm is a rod running to valve handle. As the speed of the engine increases, the weights are forced out by centrifugal force. With this momentum the collar is drawn outward, thereby drawing the governor lever and closing the throttle valve. The decreasing of speed would consequently allow the valve to assume its former position.

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The piston and rings, which should be carefully turned to ensure perfect fit, are made of fairly hard gray cast iron, and will hardly need any description.

The crank shaft bushings are a very important part of the engine, and also the stuffing gland attached to same. These glands, or stuff nuts, not only ensure perfect tightness of crank case, but also add to the length of bearing of shaft.

The sketch of the eccentric can hardly be considered in this description, as it is used only when the circulation of water is forced by pumping. The eccentric is used in connection with the eccentric strap, which operates the pump.

One of the most difficult problems in designing a gasoline motor is the sparking mechanism. It is usually found to be very intricate, made up of numerous levers, cams, etc., which are easy to get out of order. The igniter of this engine has been used and found to be very satisfactory. The method of exploding the gas in the cylinder is known as the "make and break" type igniter, and is so designed that the two points (usually platinum), one on the insulated pin, and one on the arm of the lever, are held together, and then separated with a jerk, by the small pin on piston striking the igniter lever. This makes a quick break in the circuit, so that the spark may have the highest possible voltage at the moment of the break. As the drawings fully show the construction of this part, it will be only necessary to explain the operation of the igniter itself, in order that the action may be fully understood. The spark pin or electrode is set stationary, and insulated by mica tubes and washers, which form the terminus of one side of the circuit. The other electrode or igniter lever is free to rotate on its axis, and is made gas tight, by being ground pointed at the shoulder, against the end of the bushing. This is held in place and under tension by means of the piano-wire spring, which is fastened, one end on the collar, and the other end on the bushing. The collar, if so desired, may be fastened to the lever by a taper pin. The tension of the spring also holds the arm of the lever against the spark pin. The spring is made extra long, as the tendency would otherwise be to shorten when wound and cause an uneven tension, which might cause the lever to bind against the bushing. The small pin, set in the top of the piston to strike the igniter lever, should be adjusted so that it will lift the lever to make the break in the circuit just as the piston has reached the top of the stroke.

It might be well to assure the reader that the dimensions on drawings and in descriptions are correct, and the results obtained from engines which have been built from this design have been more than satisfactory.