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. 15 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 assembling the parts went 

 on through the spring and summer. This engine, still 

 on the carriage in the Museum of History and Tech- 

 nology, 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 flanges, 

 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), anchored below 

 to a thin brass 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 mecha- 

 nism 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 ex- 

 haust-valve gear, by means of which the flow of cur- 

 rent 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 con- 

 sists 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 passes through. The present car- 

 buretor 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 muffler. 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 assembly 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 muffler 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% inches, but the bore was increased slightly 

 to 4% 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 crank- 

 shaft. 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 



" Duryea, op. <it. (footnote 5), p. 12. 



19 Letter from Frank Duryea to Charles Duryea, Novi mber 3, 

 1893, states that the engine could be run at 700 as well a 500 

 rpm. Copy in Museum files. 



16 



BULLETIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



