The two pistons were first pinned together into a single unit which was probably ringless, since it is believed the walls of the outer piston were too thin to admit rings. Because the piston no longer struck the exhaust valve, a short rod had to be screwed into the pistonhead; this pushed the valve shut at the completion of the exhaust stroke. The remaining problem, the opening of the exhaust valve, was solved by s.c.r.e.w.i.n.g a device to the side of the cylinder which operated from the sidewise motion of the connecting rod. This device shifted a small s.p.a.cer between the piston and the striker arm of the exhaust-valve rod, permitting the piston to push open the exhaust valve. On alternating strokes the s.p.a.cer shifted back out of the cylinder; therefore, no contact was made between piston and striker arm. Sometime in February 1893, the altered engine was successfully started.
At last the transmission could be tested. Will Russell had come upstairs to watch the trial, and according to a statement by him, given April 30, 1926, Frank, standing to the right of the engine and behind the rear axle, reached forward and with the combination tiller-belt-shifter, moved the belt into driving position. The carriage started forward, but as it approached the wall of the building Frank discovered that he could not get the belt back into the neutral position. In desperation, he grasped the rear axle with both hands and was dragged a short distance, attempting to stop the machine, before it struck the wall. He had, however, sufficiently r.e.t.a.r.ded it so that no damage was done.
This short trial demonstrated some of the weaknesses in the friction transmission. Since the speed of the surface of the flywheel, in feet per second, increased in proportion to the distance of the point of contact from the center, the outer edge of the belt attempted to run faster than the inner edge. This conflict of forces not only put an undue load on the motor causing a great loss of power, but it also created a tendency for the belt to work towards the outer edge of the flywheel. Conversely, when the operator desired to return the belt to neutral, it strongly resisted any efforts to slide it toward the center of the wheel, as Frank had learned from the wall-b.u.mping incident.
Furthermore, the rubber belt on the friction drum had worn so badly that it had to be replaced at least once during the brief experiments.
[Ill.u.s.tration: FIGURE 18.--IGNITION CHAMBER, switch, and breaker contacts of the present Duryea engine.]
At this point, Frank and Markham felt that the carriage was anything but satisfactory. While they were trying to decide what steps should be taken next, Frank added one last improvement to the engine. Fearing that the uncooled cylinder might suffer damage from the excessive heat, he constructed a copper water jacket in two halves, drew them together around the cylinder with clamping rings and soldered the seams. Asbestos packing sealed the end joints where the jacket contacted the cylinder.
Thinking back, Frank does not recall that he ever used a water tank with this engine, though he does remember adding water through the upper jacket opening. The engine was run only for a few brief periods following this addition.
Obviously this collection of patchwork could not fulfill their needs for an engine. First, it would be next to impossible to start if the body was placed on the running gear, as the flywheel then would be practically inaccessible. The absence of rings on the piston caused a further loss of power to the already overloaded engine. The flywheel was too light. The absence of any form of governor left the operator with no control over the engine speed. Ignition was poor, partly owing to the hot-tube arrangement, and partly to the excessive distance between the engine and the carburetor. Frank wrote his brother Charles on February 6[17] that in his opinion the mixing chamber was so far from the engine that the gasoline could not be drawn into the cylinder as liquid, and it was too cold to vaporize and go in as gas. Thus he had difficulty in getting the engine started. When it did start the explosions were unm.u.f.fled. Less important to him than these defects, however, was the awkward and unsightly wooden engine mount.
Description of the Automobile
Sometime in the early part of March, Frank convinced Markham that he could construct a new and practical engine, using only previously tried mechanical principles.[18] Drawing up new plans for this engine, he took them to Charles Marshall who began work on the patterns for the new engine castings. After the patterns had been delivered to the foundry, Frank left Springfield for a short vacation in Groton, Connecticut, where he visited with his fiancee. On May 17, 1893, several weeks after his return to Springfield, they were married.
The engine castings were undoubtedly received from the foundry prior to Frank Duryea"s marriage, and the work of machining and a.s.sembling the parts went on through the spring and summer. This engine, still on the carriage in the Museum of History and Technology, is cased with a water jacket, and has bases on top to support the front and rear bearings of the starting crankshaft, and a base with port on the upper right side where the exhaust-valve housing was to be bolted. On the underside are two f.l.a.n.g.es, forming a base for seating the engine on the axle. A separate combustion chamber is cast and bolted to the head. Inside this chamber are located the igniter parts of Frank"s electric ignition system. The fixed part, an insulated electrode, is screwed into the right side of the chamber and is connected with the ignition switch outside, to which one of the ignition wires is attached. A breaker arm inside is pinned to a small shaft extending through the top of the chamber. Around the breaker-arm shaft is a small coil spring (originally a spiral spring, according to the letter of Charles Duryea shown in fig.
17), anch.o.r.ed below to a thin bra.s.s finger extending toward the right side of the car, and above to a nut screwed tightly onto the shaft. This nut is also the terminal for the other ignition wire. The action of the spring keeps the breaker arm and the electrode in constant contact until the push rod on the end of the piston strikes the arm and separates the two parts. Breaking contact then produces the ignition spark. Since the mechanism would spark at the end of both the exhaust and compression strokes, the battery current is conserved by a contact strip, on the underside of the larger exhaust-valve gear, by means of which the flow of current is cut off during the greater part of the cycle.
On the left side of the combustion chamber is bolted the housing containing the tiny intake valve. A comparatively weak spring seats this valve in order that the suction created by the piston can easily pull it open. Clamped onto the valve housing is the intake pipe, enclosing the choke and carrying the carburetor on its forward side. The choke consists of two discs which block the pipe, each with four holes at the edges and one in the center. Turning one disc by means of a small handle outside, so that the four outer holes cannot coincide with those in the other disc, decreases the flow of air and causes all air to rush through the center hole, where the tiny carburetor tube pa.s.ses through. The present carburetor was transferred over from the first engine. When Frank later installed the engine on the carriage he noticed the close proximity of the intake pipe to the open end of the m.u.f.fler. Believing that the fumes might choke the engine, he attached a long sheet-metal tube to the intake pipe so that fresh air would be drawn in from a point farther forward on the vehicle.
Moving to the right side of the engine brings the exhaust-valve a.s.sembly into view. This valve is contained in a casting bolted over the exhaust port in the side of the cylinder, and from the casting a pipe leads to the m.u.f.fler underneath. The valve is pushed open by a rod connected to a crank which is pinned to the lower end of a shaft carrying an iron gear on top. This gear is in mesh with a fiber gear, keyed to the upper end of the crankshaft, with half the number of teeth. This ratio permits the opening of the exhaust valve on every other revolution.
The crankshaft of the first engine was retained for the new engine, thus giving the two engines the same stroke of 5-3/8 inches, but the bore was increased slightly to 4-3/8 inches. With this larger bore and with the engine speed increased to 500 rpm, Frank rated this engine at 4 hp.[19]
A heavier flywheel, with a governor resting in the upper recess, was pressed onto the crankshaft. As the operator of the vehicle had no control over the carburetor once he climbed into the seat, this governor was necessary to maintain regular engine speed. Its function was to move a slide on the exhaust-valve unit to prevent the valve from closing.
Thus the engine, with the suction broken, could not draw a charge on the next revolution. During the recent restoration of this carriage it was found that while most parts are still intact, nearly all of the governor parts are missing. A description of them must therefore be based on the recollections of Frank Duryea, along with certain evidences seen on the engine.
[Ill.u.s.tration: FIGURE 19.--UNDER SIDE of exhaust valve mechanism showing electrical contacts that give spark only on every other revolution.]
Just on top of the flywheel, and surrounding the crankshaft, rest two rings, 3-7/8 inches in diameter. Into the opposing surfaces of these rings are cut a series of small inclined planes, appertinent to each other. On the outer circ.u.mference of the upper ring two pins pa.s.s through a pair of lugs mounted in the flywheel, causing the ring to rotate with the flywheel, yet permitting vertical movement. Underneath, the other ring is allowed to turn slightly when, by means of two connecting links, the arms of the governor push against them. These two arms, each constructed like a right angle and pivoted at the apex, are arranged directly opposite each other far out in the flywheel recess. As a weight on one angle of the arm presses outward by centrifugal force against a spring, the other angle presses inward against the connecting link mentioned above. The turning of the lower set of inclined planes against the fixed set above raises the upper ring and the fork resting on it. The upward movement of this fork, which is a continuation of an arm pivoted to a bracket midway between the crankshaft and the slide carrying the exhaust valve stop, causes the other end of the arm to drop, pulling the slide down with it. In this manner the closing of the exhaust valve is blocked, preventing the intake of the next charge, and therefore the engine misses one or more explosions until it slows to its normal speed.
A starting shaft is mounted above the engine casting by a cast-iron bracket on either end. The front end of the shaft has a bevel gear which is held by a coil spring behind the front bracket, just out of contact with a bevel gear pressed onto the upper end of the crankshaft. The short rear portion of the shaft is a tube which slides over the main shaft. Fitting the removable handcrank to the squared end of the hollow shaft and turning the crank clockwise, will advance the forward section of shaft through the medium of a pair of inclined collars. With the bevel gears now engaged the engine may be cranked. When ignition begins, the inclined collars slide back down each other"s surfaces, the shaft is again shortened, and its bevel gear springs free of the one on the crankshaft.
[Ill.u.s.tration: FIGURE 20.--PISTON AND CONNECTING ROD of second engine.
Screw on rod is where oil is poured into connecting rod to lubricate wrist pin and crankshaft.]
While Frank worked on his engine, he realized that certain parts of the old running gear would need to be altered or replaced. In view of the heavier and more powerful engine, he felt the old wheels, probably having compressed band hubs, were inadequate. He procured a set of new, heavier wheels[20] with Warner-type, cast-iron reinforced hubs. The angle iron frame, apparently st.u.r.dy enough to carry the added weight, was retained, but it was decided to install a heavier rear axle.[21] The front axle a.s.sembly was at first allowed to remain unchanged, as was the steering apparatus. A short time later when the engine and friction transmission were bolted in place on the running gear, Frank saw that the rigidity of the framework had an undesirable effect. When the vehicle pa.s.sed over any unevenness in the shop floor, the framework was distorted and caused the jackshaft bearings to bind tightly enough on the shaft to prevent its being turned by hand. In order to provide the 3-point suspension necessary to eliminate this distortion, Frank attached the forward parts of the framework to an extra wooden spring bar, installing between this bar and the front axle a vertical fifth wheel of the type ordinarily used in a horizontal position in any light carriage.
Frank next calculated that with the faster running engine the speed of the vehicle would be about 15 miles an hour, too much for the heavily loaded wheels. As he intended to make use of the original transmission, he decided to decrease the speed by increasing the size of the friction drum. He accomplished this by sliding a heavy fiber tube over the original drum, bringing its diameter to approximately 14 inches. The original shipper fork carriage was improved by separating the original bearings to a greater distance, and eliminating one of the two bearings on one end. This permitted a smooth and free operation of the small sliding carriage.
In August 1893, possibly as a result of indoor experiments, Frank discovered that the chains running from the small 5-tooth[22] jackshaft sprockets to the large, bronze, wheel sprockets were tight at some times and loose at others. This caused considerable unnecessary noise. The difficulty apparently was the result of the sprockets being cast and not machined. The patternmaker had said he believed he could make the pattern accurately enough so that no machining of the castings would be necessary. Nice castings were produced, but "these sprockets were the reason why an unusual construction was put on the crankshaft [meaning jackshaft]," explained Frank Duryea during an interview at the National Museum on November 9, 1956. Elaborating further, in reply to the queries of E. A. Battison, of the Museum"s division of engineering, Duryea told of the problem and the solution when he explained that the sprockets had places where the shrinkage was not even. The hot metal, contracting as it cooled, did not seem to contract uniformly, creating slightly unequal distances between teeth. This resulted in the chain hanging quite loose in some places and in others the tightness prevented adjustment. He contacted Will Russell, foreman of the Russell shop, where the automobile was made, and Russell showed him a device, built by George Warwick, who had made the Warwick bicycle. It was an internal-cut gear, according to Duryea"s description, with sprocket teeth on its periphery.
With sprockets outside and normal teeth inside, the wheels were about 6 inches in diameter, externally.
These little internal-gear sprockets were hung on double-shrouded pinions secured to each end of the jackshaft. A solid disc or housing fitted against both ends of the pinion to prevent the internal gear from working off sideways. Duryea explained the function of these unique little parts: "as soon as tension came on that ring gear that we talked about, it not only tightened the chain hanging on this sprocket on the upper side, but it tightened it on both sides. [The sprocket]
rocks right out: both sides of the chain are tight."
This feature is one rarely encountered elsewhere, and Duryea, later in the interview said, "To tell you the truth, I think I was just a little bit ashamed about the thing, because I had to pull it off. I didn"t like the looks of it after I got it on."
Two small tanks, each with a capacity of approximately two gallons, were mounted over the engine in the positions they still occupy, the one on the left for gasoline,[23] the other for water. The small fitting under the gasoline tank has a thumbscrew shutoff and a gla.s.s-sight feed tube, leading to the carburetor. The water tank, an inch longer than the gasoline tank, communicates with the water jacket of the engine through two pieces of half-inch pipe, entering the jacket from above and below.
The overflow tank, holding just over a gallon, is suspended between the rear axle and the flywheel.
A number of m.u.f.flers were constructed for the engine.[24] The first experimental one was built of wood, being a box 6 6 15 inches with a hole for the exhaust pipe in one end and a series of small holes in the opposite end. Inside, Frank arranged metal plates which were somewhat shorter than the depth of the box. Every other one was attached to the bottom of the box; the intermediate plates were fastened to the top.
This contrivance m.u.f.fled the sound considerably, but, as might be expected, soon began to smoke. There can be little doubt that it was replaced before any of the outdoor trials began. Another type consisted of a cylindrical metal sh.e.l.l, perhaps six inches in diameter and ten or twelve inches long. Here a series of perforated baffle plates were inserted, with alternating solid plates having parts of their external edges cut away. Two bolts running the length of the m.u.f.fler held on the cast-iron heads in a manner quite similar to the Model-T Ford m.u.f.flers of later years. Though partially satisfactory, Frank, in a November 6, 1957, interview, complained that it made a metallic sound. Perhaps this was the m.u.f.fler he used from September to November 1893.
[Ill.u.s.tration: FIGURE 21.--ILl.u.s.tRATION OF THE NO. 2 SAMSON BATTERY used by the Duryeas in their vehicle. (Smithsonian photo 46858.)]
On August 28 Frank wrote to Charles saying the carriage was almost ready for the road and that he hoped to take it out for a test on the coming Sat.u.r.day, "off somewhere so no one will see us...."[25] There is no evidence showing whether the amount of remaining work permitted the proposed trial on September 2. The body was finally replaced on the running gear, at which time it was found necessary to raise the seat cushion several inches by the insertion of a framework made of old crating boards. This allowed sufficient room between the seat and the frame to suspend the batteries and coil. Six no. 2 Samson batteries were contained in this s.p.a.ce, three on each side, in rows parallel to the side of the vehicle. The Samson battery consisted of a gla.s.s jar containing a solution of ammonia salts and water, with a carbon rod in the center, housing a zinc rod. It is difficult to understand why they used Samson batteries rather than dry cells; perhaps they were concerned with the mounting cost of the machine and were making use of parts already on hand.[26] A coil, possibly from an old gaslight igniter system, accompanied the Samson batteries under the seat. This original coil is now missing.
The iron dash frame, previously recovered and provided with a rain ap.r.o.n to be pulled up over the knees in the event a heavy rain blew in under the carriage top, was bolted back in place. Frank and Mr. Markham gave the carriage a quick painting; later Frank admitted, "the machine never had a good job of painting."[27] Before the motor wagon actually got onto the road, a reporter on the _Springfield Evening Union_ got some statistics on it and an item appeared on September 16, giving the first public notice of the machine.
=NO USE FOR HORSES.
Springfield Mechanics Devise a New Mode of Travel.
Ingenious Wagon Now Being Made in This City for Which the Makers Claim Great Things.
A new motor carriage, which, if the preliminary tests prove successful as is expected, will revolutionize the mode of travel on highways, and do away with the horse as a means of transportation, is being made in this city. It is quite probable that within a short time one may be able to see an ordinary carriage in almost every respect, running along the streets or climbing country hills without visible means of propulsion.
The carriage is being built by J. F. Duryea, the designer and B. F.
Markham, who have been at work on it for over a year. The vehicle was designed by C. E. Duryea, a bicycle manufacturer of Peoria, Ill., and he communicated his scheme to his brother, who is a practical machanic in this city.
The propelling power is furnished by a two-horse power gasoline motor situated near the rear axle and which, when started, runs continuously to the end of the trip, notwithstanding the number of times the carriage may be stopped. The speed of the motor is uniform, being about 500 revolutions a minute, and is so arranged that it gives a multiplied power for climbing hills and the lower the rate of speed the greater power is furnished by the motor. The slowest that the carriage can be driven is three miles an hour and the speed can be increased to fourteen or fifteen miles an hour. The power is transferred from the driving wheel of the motor, which runs horizontally with the main shaft by an endless friction belt running on a drum wheel. The belt is controlled by a lever within easy reach of the driver and is shifted along the drum wheel to increase or decrease the speed. The driving wheel is about twenty inches in diameter, having in its center a depression to which the belt is shifted to stop the carriage.
The carriage can be reversed by shifting the belt from the end of the drum, which gives the forward motion to the opposite side beyond the depression in the driving wheel. The power which has been transferred to the driving shaft from the motor is in turn transferred to the two rear wheels of the carriage by a combination gear and sprockets. An endless chain connects the sprockets on the carriage wheels to the sprocket wheels on the driving shaft. All of the motive power is located under the body of an ordinary phaeton, the hight of which is not increased by the machinery. The motor is started by a crank which is easily applied to a shaft in the rear of the carriage and the gasoline is ignited in the cylinder by electricity. An automatic device stops the flow of gasoline into the cylinder when the motor ceases running. The gasoline is carried in tanks, which hold about two gallons, and which will run the carriage for about eight hours. The wagon is guided by a bicycle bar, and the speed is also controlled by this bar.
The method employed in this is as follows: To start the carriage press the lever down; to reverse it throw the lever up and to guide the wagon turn the lever either to the right or left. The front axle instead of turning horizontally plays up and down, in order that the machinery may be on a level with the rear wheels, while the front wheels are set on the axle by a pivotal joint and are connected with the guiding lever by bars with ball bearings. The carriage complete weighs about 220 pounds, and the essential features are already covered by patents while others are pending.
It is estimated that the carriages can be sold for about $400, and a stock company will probably be formed to manufacture them.=
[Ill.u.s.tration: FIGURE 22.--FROM THE _Springfield Evening Union_, September 16, 1893.]
Toward the latter part of the following week, Frank was ready to give the product of his labors its first road trial. On September 21 the completed carriage was rolled onto the elevator at Russell"s shop.
Seeing that the running gear was too long for the elevator, they raised the front of the machine, resting the entire weight of 750 pounds on the rear wheels. Once outside the building, they pushed it into an area between the Russell and Stacy buildings. After dark, "so no one will see," Will Bemis, Mr. Markham"s son-in-law, brought a horse and they pulled the phaeton out to his barn on Spruce Street.[28] There, on Spruce and Florence Streets the first tests were made. The next day Frank wrote his brother saying, "Have tried it (the carriage) finally and thoroughly and quit trying until some changes are made. Belt transmission very bad.[29] Engine all right." He did admit the engine seemed to be well loaded most of the time. He also had an idea in mind to replace the poor transmission, explaining the plan to Charles: "The three gears[30] on secondary shaft have friction clutches, the two bevel gears on same shaft are controlled by a clutch which frees one and clutches the other at will. This provides a reverse."