IMPROVEMENTS IN APPARATUS FOR DETERMINING AND INDICATING THE RATE OF SPEED OF MACHINES, CARRIAGES, AND THE SURFACES OF BODIES WHEN IN MOTION
Year: 1873

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN APPARATUS FOR DETERMINING AND INDICATING THE
RATE OF SPEED OF MACHINES, CARRIAGES, AND THE SURFACES OF BODIES
WHEN IN MOTION.”—A communication from abroad by John Walter
Osborne, of Washington, District of Columbia, in the United States
of America.
COMPLETE SPECIFICATION filed by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 29th May 1873, pursuant to the 9th Section of
the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middle-

page_text: CARRIAGES, AND THE SURFACES OF BODIES WHEN IN MOTION," and have
petitioned Her Majesty to grant unto me, my executors, administrators,
and assigns, Her Royal Letters Patent for the same, and have made
solemn Declaration that the said Invention is communicated to me
from abroad by John Walter Osborne, of Washington, District of
Columbia, in the United States of America.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention,
and in what manner the same is to be performed in and by the following
statement, reference being had to the accompanying Drawings, and to
the letters and figures marked thereon, that is to say :-
This Invention has reference to the class of machines used for the
purpose of determining the velocity or rate of speed at which shafting
or wheels are rotating; also for determining the surface speed or rate
of motion of bodies, such for example, as the surface speed of metal
work in lathes and planing machines, that is to say, the speed with
which the said surfaces pass the cutting tool. It consists in the com-
bination of an index hand or pointer, a graduated dial, a current
receiver and retarding spring, with a current generator, whereby the
force of the current produced in any fluid acted upon by the generator
can be indicated upon the dial, which may be so graduated as to express
the number of revolutions which the generator makes per second, minute,
or other unit of time, and whereby the trouble of counting and rating the
speed by time is completely avoided.
And in order that the said Invention may be fully understood, I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed two Sheets of Drawings,
the same letters of reference indicating corresponding parts in all the
Figures.
Figures 1, 2, 3 (Sheet 1) illustrate the construction of a rate guage
or speed indicator in which dense fluids, such as oil, glycerine, or water
are used. Figures 4, 5, 6 (Sheet 2) show the parts of a similar instru-
ment adapted to use air as the medium in which a current is produced.
The principle in both cases is identical, and as the construction is also
essentially the same the corresponding parts in each set of Figures are
indicated by the same letters,

page_text: Figure 1 is a front elevation of the guage, showing the index hand d
and the graduated scale on which it indicates the number of revolutions
which are being made per second, minute, or other unit or period of
time at the time of observation. e is a light spring attached at e¹ which
acts as a stop, and softens the blow struck by the pointer on arriving
at either end of its course; B is a reservoir connected with the closed
chamber A to contain any excess of liquid; G is a foot or stand shown
in part broken away by which the guage can be firmly attached to
any convenient and suitable place.
Figure 1 is a front elevation of the guage, showing the index hand d
and the graduated scale on which it indicates the number of revolutions
which are being made per second, minute, or other unit or period of
time at the time of observation. e is a light spring attached at e¹ which
acts as a stop, and softens the blow struck by the pointer on arriving
at either end of its course; B is a reservoir connected with the closed
chamber A. to contain any excess of liquid; G is a foot or stand shown
in part broken away by which the guage can be firmly attached to
any convenient and suitable place.
Figure 2 is a perpendicular cross section at right angles to the face.
of the guage.
The outer case is here shown consists of a cylindrical box or drum
A, A, A, A, one end of which is closed by a disc of glass or mica K, K,
(I prefer the latter) made water or oil tight by the pressure of the
screws acting on the ring H, H, and by suitable packing if necessary.
I, I, is a circular plate or diaphragm which serves as a support for
parts afterwards to be described; it is perforated at the top and bottom
by small holes f,f, to admit of the passage of a fluid. Two holes b, b¹,
also connect the guage box with the reservoir B. N is a short spindle
or shaft passing through the stuffing box L. To its outer end a pulley M
of suitable size is firmly attached, to which rotary motion is communi-
cated by a belt or chain working over the shaft or pulley, the speed
of which is to be rated. The inner extremity of the shaft N carries
the "current generator," which consists of a number of flat radial vanes
or fans C, C, screwed fast to the shaft, the plane of each vane being
at right angles to the face of the gauge, and to the plane in which they
rotate when set in motion by the driving mechanism outside. The
number of these vanes, shown in the Drawings, is eight, which will be
found in many cases to give satisfactory results; but for low speeds
the number may be increased, and for very high speeds fewer vancs will
answer well. Their form may be variously modified, but that shown
in the Drawings has been found very serviceable.
a is an arbor of small diameter running in very delicate bearings
pierced through the plate I, I, and the bow F; on its outer extremity
it carries the pointer d, visible through the glass or mica plate in front,
to its inner end the arm of the "current receiver " D is attached, all
three being rigidly connected. The current receiver consists of a vane

page_text: which may be dish shaped, as in the Drawing, so as to acquire stiffness,
and enable it better to receive the force of the generated current. It
should be made of very thin and light material, and should when in
situ counterpoise the pointer as nearly as possible. The size and
position of this vane must be such that it shall not touch the vanes
of the current generator. With the arbor, one end of the spiral spring E
is connected, while the other is made fast at E' in such a way that the
pointer d always lies in contact with the stop spring e with greater
or less force when the instrument is at rest.
Figure 3 is a vertical section of the gauge parallel to its face taken
along the dotted line X, X, in Figure 2, shewing the essential parts
inside the plate I, I. The position of the pointer outside the plate
is also indicated by its dotted outline, and the direction in which the
current generator should revolve by the arrows. To put this instrument
in working order it is filled through the orifice, closed by a screw plug
at the top of the reservoir B with water, oil, glycerine, petroleum, or
some other suitable liquid. I find a mixture of one part sperm oil and
two parts refined petroleum to answer very well. It will be found best
to keep the guage box at all times perfectly full, to insure which a large
excess may be kept in the reservoir B. If now the shaft N be made
to rotate in the direction shown by the arrows a current of the liquid
employed will be created, which impinging on the receiving vane D
will tend to deflect it, and cause the revolution of the arbor a. The
pointer d will indicate to what extent the resistance of the spring has
been overcome, and its position will be constant for the same number
of revolutions per minute which the pulley makes. An increase of
speed in the latter will increase the force of the current, and therefore
determine the onward progress of the pointer, while a decrease will be
followed by its retrogression. As the position of the pointer for any
particular number of revolutions per minute will be constant, a con-
tinuous scale can easily be constructed when a sufficient number of
points upon the dial indicating different speeds have been found by
actual experiment. It is also evident that the divisions on the scale
may be made to have direct reference to the revolutions which the
shaft or machine to be rated makes, irrespective of the relative size
of the driving pulley and the driven pulley upon the shaft of the current
generator; or that the readings may be made to give the number of feet
per minute or miles per hour which pass over the pulley on said shaft,

page_text: or which pass any other pulley or wheel in mechanical connection
with it.
Although it is recommended in the foregoing to have the guage box
quite full of the liquid employed, yet this condition is not theoretically
essential, the principle involved being the same when the instrument
is but partially filled, provided the receiving vane is immersed and so
placed as to receive the force of the generated current. In practice
however I believe the perfectly full condition will be found best cal-
culated to give uniform results.
Figure 4 is a front elevation of a guage similar in all respects to that
previously described, but adapted for the employment of atmospheric air
as the fluid in which to produce the vortical current.
Figure 5 shows a vertical cross section corresponding to that marked
Figure 2.
Figure 6 is a vertical section parallel to the face taken along the
dotted line y, y, in Figure 5, corresponding to that shewn in Figure 3.
A detailed description of these Drawings on Sheet 2 is unnecessary;
it will be sufficient to point out the differences in construction which
the use of a gaseous fluid renders desirable.
It will readily be seen that although the force which an air current
exerts upon the receiving vane is constant for one and the same speed,
and therefore serviceable, it is much less than that which results from
the rotation of a dense and non-elastic fluid; it follows therefore that
the manner of suspending the rotating or oscillating arbor carrying
the receiving vane and pointer must be much more delicate, and the
spring proportionably weaker. The delicacy may be accomplished by
letting the extremities of the arbor terminate in points and run in
hardened steel cavities or in jewels. The form of spring shown in the
Drawing is found desirable when very slight torsional force is required.
The reservoir is dispensed with as a matter of course, and the necessity
for the close fitting of the glass disc (which is preferable to mica in this
case as well as for the stuffing box at the back is not felt for obvious
reasons, the latter being replaced by an ordinary bearing L'. Finally,
the scale is marked upon the diaphragm I inside the glass in place of
outside, as when heavy fluids are employed.
Figures 4, 5, and 6, also illustrate the facility with which an in-
strument of this kind may be attached to a suitable handle P, and

page_text: so rendered portable, and also indicate the way in which a friction
roller Q (Figures 4 and 6) attached to a movable arm or link can be
employed to drive the current generator in place of a belt. The
handle P, shewn in part in Figures 4 and 6, may be fixed in any radial
direction by means of the movable strap 0, 0, and split taper screw R,
with its compressing nut S, shewn in the Drawings; or a stand or base,
as in Figures 1, 2, and 3, may be substituted for the handle if it is
desired to make the guage fast. The friction pulley Q is covered on its
outer edge with rubber or leather to prevent a slip between it and the
pulley M, or between it and the moving body to be rated, with which
it may be brought in contact. If desirable it can be easily removed to
give place to a belt or other means of driving the shaft N.
My Invention will be found to obviate altogether the necessity for
"timing" moving apparatus by the watch; it is applicable for determining
the speed of printing presses, spinning and grinding machinery, paper
mills, centrifugal machines, and shafting in factories, also for keeping
a check upon the regular performance of motors generally, for deter-
mining the proper cutting speed of lathes and planers, and for aiding
in the maintenance of the maximum speed of automatic tools and
engines consistent with the production of satisfactory work. It is also
applicable to the determination of the speed of steam and other land
carriages, of marine engines, and of the belting of machinery generally.
When used for rating or guaging the speed of carriages or loco-
motives, the scale should express or indicate the speed probably in
miles per hour. In this application the axle N must be driven by 2
connecting it in some suitable way with one of the carriage wheels,
and the revolutions of the said wheel must be converted into distances
traversed by its periphery along the road or track, such distance being
expressed upon the scale in place of revolutions. In like manner the
surface rate of speed of bodies in motion, say for example, metals in a 3
lathe or planing machine, can be expressed upon the scale in feet per
minute. This device will also be found useful if it is desired to obtain
an indication or alarm whenever a shaft or other mechanism has
acquired a certain maximum or minimum rate of speed, as for instance,
by effecting an electrical connection by which any necessary mechanical 3
effect can be produced whenever the pointer reaches a certain place
in its path.

page_text: Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention is, the
combination of a revolving mechanism for producing within a chamber
a vortical motion in a fluid, a resisting vane or disc actuated by the
motion of the said fluid, a spring or its equivalent giving the said vane
its resisting power, and a pointer or other moving device by which the
motion or position of the said vane is indicated, the whole constituting
a rate or speed guage, substantially as herein-before described.
In witness whereof, I, the said John Henry Johnson, have to this
my Complete Specification set my hand and seal, the Twenty-
ninth day of May, One thousand eight hundred and seventy-three.
J. HENRY JOHNSON. (L.S.)