The Evolution and Manufacture of the Central Counterpoise Governor.
Introduction of Mr. Richards.
When the stone-dressing machine was started a difficulty presented
itself. The governor was in constant motion a short distance up and
down, causing the engine to oscillate, running alternately too fast and
too slow. There was nothing that should have caused this action, so
far as I could observe. The load on the engine was constant. However
the work done on the stone may have varied, the work of the engine was
to lift the hammers, and these, being lifted successively, presented a
uniform resistance. The oscillation was not very great, as nearly as
I can remember about 12 per cent. of the speed; which would give to
each hammer a variation of thirty-six blows per minute. This, however,
produced a waving surface on the stone. The more rapid the blow, the
stronger it was and the deeper the cut. These waves were slight, only
about ¹⁄₅₀ of an inch variation in depth, but yet it was not possible
for our rubbing-machine to grind them off without great loss of time.
So we had to employ three or four stone-cutters to chisel off these
ridges, which were about 4 inches apart.
It was evident that this oscillation must be stopped. I tried to remedy
it by changing the pressure of the steam, and then by changing the
pulleys so as to run the engine faster, the speed of the governor,
however, necessarily remaining the same. But these had no effect.
Having exhausted my own stock of ignorance on the subject, I applied
to professional experts for more, and I got it. Three persons, who I
supposed ought to know, and who probably did know, all that was then
known on the subject, gave me the same advice. It was that I should get
a larger engine and a great deal larger fly-wheel. This advice did
not seem to me reasonable. I knew that the engine was large enough,
because while the governor was in the lowest position, in which it did
not open the throttle entirely by any means, the machine ran too fast.
They then told me I must have a heavier fly-wheel at any rate, and they
explained to me that the fly-wheel performed two offices--one to carry
the crank over its dead centers with an approximately uniform motion,
and the other to give the governor time to act. I replied that the
engine passed its dead centers with absolute uniformity then, as nearly
as I could see, and as was shown by the surface of the stone, and
consequently for that purpose the fly-wheel I had must be sufficient.
The oscillations were regular, occupying about 30 revolutions of the
machine, or 6 seconds of time, and had no connection with the dead
centers, and I did not see why the governor should require any time to
act. They told me that all governors required time to act, of course.
I then examined the governor more critically, and made up my mind that
its action was hindered by friction in the driving-joints at the top
of the spindle. These joints were about 4 inches apart, on opposite
sides of the spindle, and were of a character in which the force
transmitted through them to drive the balls produced a pinch between
the broad faces of the joints. The governor could not act until by
change of its speed it had accumulated force enough to overcome this
pinch, and then it moved too far. Again I applied to my authorities
for some way of getting rid of this friction. They told me that was
easy enough. All I had to do was to put a yoke on the governor spindle,
through which the governor arms were threaded and by which the driving
pressure was applied close to the balls. So for the first time I took
their advice and had a yoke put on the governor. I could not discover
that this helped the matter at all. The improvement was too trifling
to be noticed. I also saw clearly enough why this was so. The pressure
applied was lighter than that applied through the joints, but it
was also applied at a correspondingly increased distance from the
axis, so that the effect in retarding the action of the governor was
substantially the same.
I saw that if I got any relief I must find a way to it myself. So I
began studying the subject of governors. My engineering library at
that time consisted of Haswell’s Engineers’ Pocket Book. What little
book-knowledge I had respecting mechanics I had learned from Haswell.
I turned to Haswell and read what he had to say about governors.
I learned that they were conical pendulums and made half as many
revolutions in a minute as the vibrations of a pendulum whose length
was equal to the height of the cone, the base of which was the plane
in which the center of oscillation of the balls and arms revolved, and
its apex the point of intersection of the axes of the arms, if produced
upward, and that their revolutions varied inversely as the square root
of the height of this cone. I did not see that this got me out of
my difficulty at all. I then referred to the subject of centrifugal
force, with which I had made some acquaintance before, and I read this
champion mind-muddler: “All bodies moving around a center or fixed
point have a tendency to fly off in a straight line. This is termed
centrifugal force.” This did not help me any more, nor interest me much
at that time.
But I read further that the centrifugal force of a body revolving in
any given circle varies as the square of the speed. “Thus a body making
10 revolutions per minute will exert four times as much centrifugal
force as will be exerted by the same body making 5 revolutions per
minute.” The governor on my engine was making 50 revolutions per
minute, and in thinking the matter over it occurred to me that if
the governor could be run as fast as my machine, namely, at 300
revolutions per minute, the centrifugal force of one pound would be
as great as that exerted by 36 pounds at 50 revolutions per minute.
I cried, “Eureka! I have found it.” One-pound balls in place of
36-pound balls would be easily driven. I told my experts of the great
find that I had made, and they laughed at me. They told me I ought
to know that the momentum of the balls increased in the same ratio
with their centrifugal force, _MV²_ being the expression common to
both, so, in the same circle, while the centrifugal force of the balls
at 300 revolutions per minute would be 36 times greater than at 50
revolutions, it would require also 36 times the force to drive them,
and that I would gain nothing by my proposed change, but instead I
would have to rotate also the weight that I would need to use to hold
the small balls down, and the last case would be worse than the first.
This staggered me, and I pondered awhile what I should do.
I had a friend living near by on Fourteenth Street, west of Seventh
Avenue--a Mr. Thompson, a mathematician and the author of a series of
mathematical books then largely used. So I called upon him and stated
my trouble and asked his advice. He illuminated the subject to me as
follows: “You seem to be a persevering young man; keep hard at it and
you will solve the difficulty by and by.”
In my despair I just had before me this one thought: The friction must
be cured at any rate. After a time I thought that if I made a long
joint at the top embracing the center of gyration of the counterpoise,
so that the pressure required to drive the balls and counterpoise would
be applied at some distance from the axis of the spindle and for that
reason would be much lighter, and also would be normal to the surface
of the joint-pin instead of being a pinch between opposite faces, the
difficulty would be cured, as the force to overcome the friction would
be exerted at the ends of levers 50 or 100 times the radius of the pin.
I felt so sure of this that I risked making a governor with a single
joint at the apex of the cone, as originally employed by Watt, thus
making the governor more sensitive, as the height of the cone would not
be changed at both ends, still fortunately holding to my little balls
and high speed, though I cannot tell why. The joint at the top I made 6
inches in length.
When this governor was started, the trouble absolutely vanished. The
engine ran with perfect uniformity while the load was constant. I
use the adjective “perfect” advisedly, for the governor slide was as
motionless on the spindle as if it were screwed tight, and the governor
proved to be the most sensitive possible index of the variations of
speed. When the belt was thrown off to the loose pulley the engine
ran idle. The counterpoise then rose promptly but gently to its fixed
highest position, and stood there motionless until the belt was thrown
on and the hammers were started, when it moved as gently but promptly
down to its lower position and stood there again motionless so long as
the hammers were running. We could not detect by the eye the variation
in speed that caused this action of the governor. The heaviest load
on the engine, however, was dragging rapidly the two tables loaded
with stone. This caused the governor to settle still further, but
always the motion of the engine seemed to be the same so far as I could
detect. The surface produced on the stone left nothing to be desired.
The machine cut true planes, free from any windage, and the surfaces
were left so smooth that the rubbing-machine had but little to do, and
kept up with the cutting-machine very easily. The governor fascinated
everybody who witnessed its operation.
[Illustration: The First Porter Governor.]
I first made the drawing for the governor with the weight hanging to
the slide. Mr. John McLaren, a machinist who had done good work for
me, when I showed it to him said, “Why don’t you turn your weight
upside down and put it between the arms?” I was not long in acting upon
this suggestion, and that made the Porter governor complete. I had it
described and illustrated in the _Scientific American_. They took a
photograph of it as photographs were taken in those days--that is, they
sent their artist up to make a sketch of it, and this sketch (shown
here) and description will be found in the _Scientific American_ of
October 9, 1858. This governor has never been changed by me except in
the shape of the counterpoise.
I believed the mathematics of my advisers to be sound, and that the
perfect action of the governor was obtained entirely by the long
driving-joint, which I supposed would have enabled the 36-lb. balls
at 50 revolutions per minute to do just as well as 1-lb. balls at 300
revolutions, but I never tried the experiment.
In that belief I remained for 50 years. Now, at the age of over 80
years, after long rest from business activities, in revising these
reminiscences for publication, the idea has first occurred to me,
and has grown into a conviction, that my advisers were wrong here as
they had been in every other respect. They overlooked the fact that
the angular velocity of the driving-joint increased equally with that
of the balls, so that the ratio between them would remain constant.
The law that the driving force required increases as the square of
the speed imparted applies only to the original source of power, as,
to the force of the steam exerted in the cylinder of an engine, the
motion of the piston remaining the same, and to the transmitting belts
or gears whose speed also remains the same. At all these points the
force exerted must increase as the square of the speed imparted; but
this does not apply to the pressure exerted in the governor joint. Its
speed does not remain the same, but increases with that of the balls.
So, while the centrifugal force of the balls, changes in which produce
the vertical movements of the counterpoise, varies as the square of
the speed, the force required to be exerted in this joint to drive the
balls, and which produces the friction to retard these movements, does
not increase at all, whatever the speed of revolution may be. This
fact, unobserved by me or any one else so far as I ever heard, has all
the time been the secret, a pretty open secret when once seen, of the
surprising combination of sensitiveness and stability in the action of
this governor which has led to its general use, and at which I myself
have never ceased to wonder because I was ignorant of its cause. This,
however, was not the only time that I builded better than I knew.
I can imagine some persons, after having read the above explanation,
to say, some of them perhaps flippantly, and some possibly sneeringly,
“To a properly educated engineer this is obvious at a glance.” I think
it will be so hereafter, but has it been so hitherto? If any one will
produce the record of its observation I will cheerfully yield to him
the priority and will congratulate him upon it.
Some things, however, make me doubt if this observation has ever been
made. At the London Exhibition of 1862 this governor attracted much
attention from its novel appearance, rapid rotation and remarkable
action. Many engineers spoke to me about it. In their conversation
I observed two things: first, no one ever asked me a question, but
every one explained its action to me; and second, while each had an
explanation of his own to make, they all agreed in a fundamental
respect. Their minds ran in the same groove. They considered the
governor only in its theoretical action. No one ever took notice of the
incident of friction, which was the controlling factor. An improved
governor was in their view one contrived in some way to free the
governor from the limitation to its action, which is imposed by the law
of the conical pendulum, and every one explained to me how my governor
was adapted to do this.
The following illustrates this universal view among English engineers:
In the Appendix to the 10th edition of Rankine’s “Manual of the
Steam-engine and other Prime Movers,” published in 1882, one reads
as follows: “ISOCHRONOUS GOVERNORS. The ordinary governor is
not isochronous; for when, in order to adapt the opening of the
regulating-valve to different loads, it rotates with its revolving
pendulums at different angles to the vertical axis, the _altitude_ of
the cone assumes different values, corresponding to different speeds.
_The following are expedients for diminishing or removing this defect._
1. _Loaded Governor_ (Porter’s).--From the balls of the common
governor, whose collective weight is (say) _A_, let there be hung by
a pair of links of lengths equal to the pendulum arms, a load, _B_,
capable of sliding up and down the spindle, and having its center
of gravity on the axis of rotation. Then the centrifugal force is
that due to _A_ alone, and the effect of gravity that due to _A_ +
2_B_; consequently the altitude for a given speed is increased in the
ratio _A_ + 2_B_ : _A_, as compared with that of a simple revolving
pendulum; and a given absolute variation of altitude in moving the
regulating-valve produces a smaller proportionate variation of speed
than in the common governor.”
That is the whole of it. Respecting this I have to say:
1st. The vertical motion of the counterpoise (variation of altitude),
if the links had also a single joint at the bottom, could not be either
more or less than twice that of the balls, which equal lengths of the
arms and links give also in the common governor, so in this respect the
governor is no improvement.
2d. No notice is taken of the small size of the balls or of the speed
of rotation.
3d. Professor Rankine is not responsible for this absurd piece of
reasoning.
4th. It only shows how far the English engineering mind has been from
considering the subject of hindrance to the governor action from
friction.
My governor works within the law of the conical pendulum. I never
dreamed of attempting in this form of governor to avoid it. In fact
it is this law which gives to the governor its action. A change of
speed is necessary to produce a motion of the counterpoise. But as
the governor was designed by me, this change of speed is very small,
probably no more than is required for stability, and is not sensible
in any way except in the motion of the counterpoise itself, which is
simultaneous with the most minute changes of speed.
Quite a variety of modifications of this governor are being made in
this country, but I think not elsewhere. The makers have been kind
enough to invent the name “the central counterpoise governor.” For
this I feel greatly obliged, as I should be mortified to find my
name attached to any of them. Their action is always more or less
unsatisfactory, sometimes very much so. But I do not think it likely
that the secret of the remarkable action of the Porter governor has
been detected by any of these people.
I am glad that this was not explained to me at first; if it had been
I might not have thought of the single long driving-joint, which is a
valuable feature.
When the stone-dressing machine proved to be valueless, as already
described, I found myself out of business; but the governor had
attracted so much attention and had been so favorably received that I
thought I could establish a business of manufacturing these governors,
and I am proud to say that the gentlemen already associated with me
and who had lost their money in the abandonment of the stone-dressing
machine were so decidedly of the same opinion, and I had won their
confidence to such an extent, that they furnished the money to enable
me to establish this manufacture.
I rented a shop on the second floor of a triangular building on
Thirteenth Street, at the junction of Hudson Street and Ninth Avenue,
owned by Mr. Herring, the safe-manufacturer, the lower part of which
was occupied by him for his own business. This was a large room and had
light on three sides.
I proceeded to equip this shop with the necessary tools, some of which
I purchased of Mr. Freeland, then considered the best toolmaker in the
United States, and who had gone to England and worked for some years
as a journeyman in the celebrated Whitworth Works, in Manchester, for
the purpose of learning everything that was known there. Those which
Mr. Freeland could not supply I obtained from Geo. S. Lincoln & Co., of
Hartford, Conn.
During the time these tools were building I was waited upon by Mr.
Chas. B. Richards, who was then removing from Hartford to New York
to establish himself as a designer of machinery, and who brought me
a letter from Geo. S. Lincoln & Co. I was at that time engaged in
scheming as well as I could a machine for drilling the arms and balls
and counterweight and spindle of my governor, and immediately employed
Mr. Richards to assist me in getting out the drawings for this machine.
This he did quite to my satisfaction, and the machine was made by
Geo. S. Lincoln & Co., Mr. Pratt, for so many years head of the firm
of Pratt & Whitney, afterwards the Pratt & Whitney Company, being then
their foreman; so that all my tools from that concern were made by Mr.
Pratt. He also cut for me superb iron patterns for the governor gears.
This machine always interested me very much. It solved every problem
which was involved in the perfect and rapid performance of these
operations. It had two parallel spindles running horizontally in the
same plane, one fixed and the other adjustable. Distance pieces laid
between the spindle heads insured the equal length of the arms of all
governors of the same size. The table was made with a back to it, so
that, a parallel block being laid on the table behind the arms, these
were always brought in position parallel with its back. The arms were
supported on blocks of proper height. These provisions insured that
the joint-holes, which were drilled simultaneously, should intersect
the axes of the arms and of the balls and spindle at right angles.
This machine fitted up all the governors that I ever made. I gradually
built up an excellent business in their manufacture, on account of the
extreme pains taken to produce perfect work, so that the governors
always gave the highest satisfaction.
I think of only one instance to the contrary. I sold a governor to
Mr. Winslow, of Troy, afterwards of the firm of Corning & Winslow,
the first manufacturers of Bessemer steel rails in this country under
the inspiration of Mr. Alexander L. Holley. Soon after this governor
had been shipped I received a letter from Mr. Winslow telling me that
the governor would not answer at all, and I should come and see about
it. I found the governor had been placed on a second-hand Burden
engine, which was a well-known type of horizontal engine at that time,
made in Brooklyn. The engine had been built to make 50 revolutions
per minute, but being a great deal too large for their use they had
reduced the speed to 25 revolutions per minute, and the complaint was
that every time the crank passed its centers the governor dropped to
its seat. I told them what I thought the difficulty was; that any one
could see that the engine very nearly stopped as the crank passed its
centers, and the governor _had_ to drop. To show them this action, I
disconnected the governor from the valve and throttled the engine by
hand, and showed them that the governor, when not connected with the
throttle-valve, rose and dropped on every stroke, in the same way as
when connected. They asked me what I was going to do about it. I told
them I should do nothing about it; that I presumed they might possibly
get a governor somewhere that would stand that alternation of speed
without winking, but they had better send mine back, because it was not
made for any such service.
[Illustration: CHARLES B. RICHARDS
A.D. 1858]
The following is an amusing illustration, doubtless an extreme one,
of the degree in which the lay mind may be incapable of mechanical
perception. My governors were usually set on the engine bed of
horizontal engines near the shaft, and were connected with the
throttle-valve over the cylinder by means of a bell-crank lever and a
long rod. One day a gentleman called to make a personal examination
of the governor and its manufacture, with a view to investing in the
business. I showed him a governor in action on the testing platform,
and a woodcut on my circular which represented the governor in its
position, as above described, with a short piece of the connecting-rod
attached to the lever. He looked at this cut intently for some time,
and then, putting his finger on the broken-off end of the little rod,
said, “Ah, I see; the steam enters there.” I made no reply, and he was
so much pleased with his own penetration that he invested at once.
I know of only one case in which this governor needed the help of a
dash-pot or controlling vessel. In the great plate-mill of the Otis
Works, in Cleveland, when the enormous mass of steel struck the rolls,
the governor dropped sharply to its seat, and jumped as sharply to the
upper limit of its action when this mass was shot out. Mr. Wellman,
their general manager, suggested to me an elegant arrangement of
air-chambers at the top and bottom of a cylinder, which permitted free
motion to the governor through its whole range of action, but cushioned
it on confined air at the ends.
For several years I made the counterpoise of the governor in the form
of a vase. The present form with hemispherical top was suggested by Mr.
Whitworth in 1866, and shown by me in the Paris Exposition of 1867.
It has three advantages. It is more readily turned with a circular
tool-rest, and it contains more metal and looks more mechanical.
I exhibited the governor in operation at a fair of the American
Institute held on Fourteenth Street between Sixth and Seventh avenues,
New York City (where the armory of the Twelfth Regiment now stands),
making an arrangement with an exhibitor of an engine for that purpose.
I remember that Mr. George H. Reynolds, then an engineer in the works
of Mr. Delamater at the foot of West Thirteenth Street, as he passed
it with a friend a day or two after it was started, remarked in my
hearing, “It will take a horse-power to drive that governor.” It
would not do to let any such nonsense get around as the opinion of an
engineer, so the next morning the governor was driven by a belt ⁵⁄₈
of an inch wide, and continued to be so through the fair. I was sorry
afterwards that I did not use a half-inch belt, which would have driven
it just as well, and indeed I think even a narrower belt would have
done, as the foot of the spindle was of hardened steel, a segment of
a sphere, running in a puddle of oil in a hardened step cupped to a
larger radius.
The funniest application of the governor I ever made was the following:
The Civil War had just broken out, and every Yankee was making some
warlike invention. The most ridiculous of all was a centrifugal gun.
A company was formed for its manufacture. The shot, about an inch in
diameter, was fed in at the center of a swiftly revolving wheel and
thrown out through a barrel at the periphery, with a velocity that, it
was estimated by the inventor, would carry it about two miles. This
velocity was to be got up in about one second. The governor would not
act quickly enough, and the engine was stopped. The parties heard of
my governor, and ordered one, offering to pay for it in a tempting
amount of their stock. I preferred the cash and got it. The governor
filled the bill, the shot was delivered, the velocity of revolution not
falling sensibly, but we judged by the sharp fall of the counterpoise
that it required not less than twenty horse-powers to do it.
The gun was tried on the bank of the Hudson, the Palisades opposite
being the target. The inventor declared that every shot hit the mark,
but some evil-minded persons insisted that they fell into the water
within a quarter of a mile of the shore from which they were fired.
About the same time the absurdity of sending into the field a tank of
water, a boiler, an engine and the gun, on separate wheels, connected
by pipes or belting, which would be ruined by the least damage to
anything, began to dawn on the enthusiasts, and the thing was abandoned.
I furnished one of my first governors to Mr. James Horner to regulate a
rolling-mill near Boonton, N. J., a sale which is worth recording. This
mill was employed in rolling steel pretty high in carbon into rods for
making gimlets, and the three-high train had not yet issued from the
brain of Mr. Fritz. The rolling was slow work. The resistance brought
down the speed of the engine before the governor could act, and they
could have only one pass in the rolls at a time. The workmen had to
carry the end of the rod around and insert it in the next groove after
it had run out of the former one. The rod would be black before it was
finished, and often it was difficult to get it finished at all. I do
not know of any change that so much impressed me at the time as did
that which followed the putting of my governor on this engine. The full
speed was kept up, the billets seemed to rush through the rolls, two
and even three passes could be in them at the same time, and the rods
were still at a dull red heat when finished.
This success induced me to make a raid on Pittsburg. I found there very
different conditions. They then rolled nothing but iron, so far as I
saw or heard. In the first mill I visited, after I had discussed the
subject with one of the proprietors, an old man came up to me and said,
“Do you see that chair? I have sat in that chair twenty-four years.”
The chair corroborated his story. “I watch the rolls; when a bar enters
them, I turn on more steam; when it goes out I shut it off. If you put
in a governor that will do as well, I shall be discharged. I don’t know
how to do anything else; I have a family dependent on me, and I don’t
know what I should do.” I did not hesitate long about what I should
do. I could not improve on the old man’s action. He regulated the
speed perfectly. The only result of my success would be to beggar him.
Superseding hand labor by machinery I did not in this particular case
care to be responsible for. I concluded that the Pittsburg way was
good enough for them, and took the next train for home.
The first governor I sold was to Mr. William Moller for his
sugar-refinery on Vandam Street. The engine to be regulated was an
old-fashioned beam-engine. The governor was to be set on a bracket
that we had to bolt to the wall, and a pulley some 3 feet or more in
diameter had to be made in halves and put on the shaft. To make sure
that no mistake would be made, I went down myself to make a gauge of
that shaft. I took a ³⁄₈-inch steel rod bent to span the shaft, and
made of this an outside gauge with great care. Now this was not what I
wanted, but I did not know it. I wanted an inside gauge, representing
the diameter of the shaft, and what I did make was useful only to
compare the two.
I returned highly satisfied with my work, leaving the real gauge to
be made in the shop, where it could not be compared with the shaft.
What might reasonably have been expected to happen did happen. In some
unaccountable way something happened to my gauge, and when we went to
install the governor we found the pulley had been bored ¹⁄₄ inch too
small. We had to work hard all night, and got through only just in time
for the engine to start at its usual hour in the morning. If I had sent
a man who knew his business to make this gauge I should have avoided a
lot of trouble, but I should not have learned anything.
In preparing for the establishment of the governor manufacture I
visited the works of Geo. S. Lincoln & Co., in Hartford, and saw
twist-drills in use, cutting chips instead of scraping. They attracted
my attention and I inquired about them, and was told that they made
them themselves. They kindly took me into the smith-shop and had one
made for me to witness the operation. The smith heated a round bar
of steel and swaged channels in it on opposite sides. They had quite
a set of top and bottom swages for different-sized channels. He then
took another heat on the bar and twisted it by hand, giving a gradually
increasing twist, which at the end was quite rapid. An increasing twist
was obtained in this way. The drill was held in a vise, so that only
the projecting end of it could receive the amount of twist then being
imparted. The drill had to be moved in the vise of course a number of
times. The channels were smoothed out with files, and when the drill
was turned in the lathe sharp cutting edges were developed, which
needed only to be backed off by grinding. I took one of these drills
home with me to serve as a pattern and equipped my shop with them. They
were of the highest use to me. The small ones drilled the holes for
the governor joints, and the large ones drilled the counterpoise and
the column for the governor spindle. I suppose the twist-drill had its
origin in these Hartford works.
I never saw any twist-drills in England except at Mr. Whitworth’s, and
these I thought were the funniest things I ever did see. They were
twisted by the blacksmith out of square bars and with a uniform quick
twist, were left rough, and did not fill the hole, and the ends were
flattened out in the form of the common drill to scrape, and not to cut.
When I returned from England in 1868 twist-drills were coming into
general use in this country. After 1876 the firm of Smith & Coventry
introduced them in England.
At that time almost everything in machine-shops was done in the
old-fashioned way, and accuracy depended entirely on the skill of
the workman. The tool work left much to be done by the fitter.
Interchangeability was unknown, even in screw-threads. For example,
when nuts were removed from a cylinder head, pains had always to be
taken that each nut was replaced on its own bolt, as no two were
exactly of a size. This condition developed a class of very skillful
all-round workmen; but my earliest observation showed me that in
manufacturing it was important that so far as possible the personal
factor should be eliminated. I adopted the rule that in mechanical work
there was only one way to insure that anything should always be done
right, and that was to make it impossible that it should be done wrong.
For example, in my governor gears their true running required that the
bore should be absolutely correct, both in position and in direction.
I had seen many gears bored. They were held in the jaws of a chuck and
trued by marking their projecting side when running with a piece of
chalk. It was evident that absolute truth could hardly ever be reached
in this way, and the approximation to it depended wholly on the skill
and pains of the workman. Besides, much time was lost in setting each
wheel. These objections were much aggravated in the case of bevel-gears.
I met these difficulties in this way. In standardizing my governors I
found it necessary to make eight sizes, but managed to use only three
different pairs of gears. I made a separate chuck for each of these six
wheels, the faces of which were turned to fit the top and inner ends
of the teeth, the same surfaces to which I had seen the chalk applied.
When the castings were received from the foundry the first operation on
them was to bed them to their chucks, which were covered with a thin
coating of red lead for this purpose. The workman was careful to remove
only projecting imperfections without touching the true surfaces of the
teeth. After this the gears, being held firmly to their chucks by means
of a yoke, were bored rapidly and always with absolute truth. Result:
their running was practically noiseless.
Mr. Freeland taught me the secret of producing true cylindrical
surfaces by grinding with a wheel. It was to let the swiftly revolving
wheel traverse the surface as it rotated, touching only the highest
points, and these very lightly. This avoided the danger of errors
from the springing of either the piece or the wheel, which under
strong pressure is sure to take place to some extent, even in the best
grinding-machines. I have found this delicacy of touch to be a most
difficult thing to teach the ordinary workmen. They often manage to
produce by grinding a surface more imperfect than it was before.
I took extreme pains to insure that the axes of the joint pins should
intersect the axis of the governor spindle and those of the governor
balls, and should be equidistant from the center of the counterpoise,
these parts of the joints having been turned to true spherical forms
by means of a circular tool-rest. For this purpose I employed a
feeling-gauge, consisting of a cylindrical stem fitting the hole as
drilled, with a curved arm projecting from this stem and terminating
in a point that would rub on the external surface of the balls. By
this means we almost always detected some slight inaccuracy, which was
remedied by the use of a round file. The joint holes were afterwards
finished with long reamers, the cutting portion of which was in the
middle of their length. The front end of the reamer fitted the drilled
hole and extended quite through the joint, so guiding the cutting
edges as they entered, and the back end of the reamer filled the hole
that had been reamed.
I finally tested their alignment by bringing the last of the five
joints together after the others had been united, when the forked link
should swing freely to the ball without the least tendency in either
direction from its exact place. This it always did.
Some time afterwards I adopted the plan of dispensing with heads and
washers on the joint pins, reaming the holes in the central portions of
the joint slightly smaller than those in the arms and making the pin a
hard fit in the former. There was never any tendency for a pin to get
loose in the running of the governor. I also at a later date cut the
counterpoise in two a short distance above the joints, so that the mass
of its weight did not need to be started and stopped when the speed of
the governor changed. I could not see, however, that this was of any
advantage, although when the governor balls were pulled around by hand
no motion was imparted to the mass of the counterpoise. The action was
apparently quite perfect before.