Construction and manufacture of automobiles

The following description of a 40 H. P. automobile, built by the Stevens-Duryea Company, of Chicopee Falls, Mass., may, except for certain important details which will be specifically mentioned, be taken as typical of the design of high-grade cars in general. In Fig. 1 is shown a side view of the "Model Y," 40 horsepower, six-cylinder machine, with 36-inch wheels and 142-inch wheel-base. An automobile may be divided into two parts the body and the "chassis." The former is the product of the carriage-maker's art, the latter of the mechanic's and engineer's. The chassis of this machine is shown in Figs. 2 and 3, to which reference will now be made.

The mechanism and body of the car are supported by a frame whose side members, of chrome-nickel steel, are shown at A. These are connected by four cross pieces, and are supported on the front and rear axles by the spring connections shown. The cross pieces are also pressed from chrome-nickel steel, and are hydraulically riveted to the side frames. A platform spring suspension is used at the rear, hung on connecting shackles designed to overcome the side roll met available horsepower per hundredweight of load. It also permits the power plant to be assembled as a whole and to be bolted in place without fitting. This construction, which is the distinctive point in the design of this motor, has been successfully followed by the builders for the last five years, and it is one of the things which serve to give an attractive mechanical appearance to the whole mechanism. Only one double set of universal joints is required, that connecting the propeller shaft with the transmission gearing at one end, and the differential gearing at the other.

The cylinders are grouped in three two-cylinder castings C, bolted to the crank case N. As is common with internal combustion engines in ordinary practice, they are water jacketed, there being a continuous at the forward end of the crank-shaft, as here shown, is unusual, the common construction being to locate it between the crank-shaft and the clutch. It tends, in particular, to bring more of the weight onto the front wheels, off from the heavily loaded rear wheels of the machine, and permits the reducing of the clearance over the roadbed in the center of the chassis, where there is the greatest danger of striking on high water-bars, railroad crossings, etc. It will be readily seen that more clearance is required at the center of the machine than at the axles, when crossing a hump in the road.

Two shafts mounted in the crank casing, one on each side, above and parallel to the crank-shaft, are driven from it by enclosed gearing. The one at the side shown in Fig. 5 is the cam-shaft and is provided with twelve sets of cams for operating the six inlet and six exhaust valves, whose stems and closing springs are plainly shown in the engraving. The driving gear of this cam-shaft is also connected with a pinion on the armature shaft of the magneto, whose function will be described later. The shaft on that side of the machine shown in Fig. 4, is known as the lay-shaft. Its office is the driving of the timer Y, which controls the ignition, the driving of the forced lubrication mechanism at W, and of the water jacket circulation pump.

The lubricator gives a forced oil supply with sight feed, and is always in operation when the engine is in motion. The six-throw crank-shaft is mounted in four bearings in the crank case, with two cranks between each pair of bearings. The boxes at these points are connected with the lubricator W. The lower half of the crank case forms a reservoir for the oil escaping from the main bearings. The connecting-rod splashes into this and thus supplies the pistons, connecting-rod bearings, etc., with the necessary lubrication.

The ignition in each cylinder is effected by either of two systems, the one by storage or dry battery and induction coil, and the other by means of a magneto U connected by gearing with the crank-shaft. The battery and spark coil is used in starting, while the magneto is used for regular running. The spark coils and switches are located on the dashboard. A lever on the steering wheel, as will be described, is connected with the commutator or timer T which distributes the current to the six cylinders in such a way as to enable the operator to advance or retard the spark at will.


The Carburetor and Fuel Supply

An important and rather delicate piece of apparatus essential to the operation of the gasoline engine, is the carburetor, shown at Z in Fig. 5. This receives a supply of gasoline through a feed pipe from the tank G (see Fig. 2), a supply of air through T heated by the exhaust gas for vaporizing the gasoline, and a supply of fresh air to furnish the oxygen for the charge. The gasoline is received in a float chamber, where the level of the liquid is maintained by a suitable float and valve. An automatic valve provides for a constant proportion of oxygen and fuel at widely-varying speeds. The carburetor is provided with a throttle which controls the needle valve connection in the feed pipe, together with the butterfly valve in the suction to the cylinders, thus providing the driver with means for varying the amount of charge furnished the machine; this controls the speed without shifting the gears in the transmission case. The automatic air valve is controlled from the seat by a handle Y on the dash-board, which permits the obtaining of a proper mixture for the starting. A button at the front of the radiator, where the machine is cranked for starting, also provides means for flooding the carburetor with fuel for a send-off. The throttle is controlled from a lever on the steering wheel, concentric with the spark control lever, or from an "accelerator pedal" on the foot-board.

The gasoline supply tank O is located under the front seat. It contains a partition near the bottom which saves about three gallons out of its twenty gallons' capacity, for use in emergency. By the manipulation of cut-off valves passing through the left side frame of the chassis, it is possible to use this reserve supply after the tank has been otherwise exhausted. This provision is a great comfort to the motorist at critical times.