On the train I had some time to puzzle over that car. Been working
nights to make up time lost in the day so did not hav much.
I made a sketch for you but did not show the spring that holds the
circuit breaker in contact with the spark point. That thin finger was
part of it. A spring was wound spirally--not helically--around the
projecting end of the breaker pivot and the end of the spring hookt over
the thin finger. See sketch herwith.
Just how the central end of the spring wire was fastened to the square
of the pivot I do not kno. We did in some cases bore a hole thru and
simply stick the spring thru but this put most of the action right at
the bend in the wire and it broke quickly. So in other cases we fitted a
light grooved spool or pulley and wound the spring around this and so
avoided a sharp bend. If this was used it has been lost with the spring.
A couple generations of boys playing in that barn was too many.
The Haynes steering sketch also worries me. If that vertical post came
up thru that slot in the floor the crank had to be long as the sketch
shows in order to get over to the driver conveniently. Then if he tried
to make a complete circle with it he could not reach far enuf forward to
do it easily. And he had to make a turn or two be cause H shows bevel
gears of about same size so the post had to make same number of turns
the worm made. Sketch herewith to illustrate my thought.
Yrs for the historical facts
Chas. E. Duryea
FIGURE 17.--LETTER EXPLAINING the circuit breaker spring and the brass
projection on top of the ignition chamber. Mr. Mitman was, at the time,
curator of engineering in the U.S. National Museum.]
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
screwing a device to the side of the cylinder which operated from the
sidewise motion of the connecting rod. This device shifted a small
spacer 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 spacer 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 retarded 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-bumping 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.
[Illustration: 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
unmuffled. Less important to him than these defects, however, was the
awkward and unsightly wooden engine mount.