Improvements in Speed Changing Spur Gear Trains.
Year: 1894

page_text: Date of Application, 12th Nov., 1894-Accepted, 12th Jan.. 1895
Improvements in Speed Changing Spur Gear Trains.
I. JOHN THOMSON, Mechanical Engineer, of 190 Carrolton Avenue, Brooklyn,
State of New York, United States of America, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to speed-changing spur gear trains and it has for its object
to provide a construction which shall avoid the objections due to the side thrusts
ordinarily inherent to such trains, to provide a structure in which the strains shall
be balanced as far as practicable, to provide a device in which the errors due to the
faulty development of the contour of the teeth are reduced to a minimum, and
further to provide a gear train which shall be simple, cheap and effective in mode
of operation, and shall avoid the objections to such trains as heretofore made, and
to these ends my invention consists in the various features of construction and
arrangement of parts substantially as hereinafter more particularly pointed out.
In the accompanying drawing I have shown one embodiment of my invention,
sufficient to enable those skilled in the art to make use thereof, and while the form
shown is the preferred form, it is to be understood that my invention is not limited
to the construction and arrangement of parts therein set forth, but that the same
principles of invention may be applied in various modified forms producing
substantially the same results. Furthermore I have shown my invention in a form
adapted for use in water meters, and the invention is especially useful in this
connection, but it is to be understood that it can be used in many and various
places where the object is to produce the minimum of frictional resistance, the
maximum of durability, and the lowest cost of manufacture.
In the drawings:
:-
Fig. 1 is an elevation of the train shown as applied to the casing of a water meter,
which latter is indicated in the dotted line A. The front pillar 5 is omitted in this
figure for clearness.
Fig. 2 is a top plan view of the train, the upper plate 3 being removed.
Figs. 3 and 4 are diagrams illustrating the principle and mode of operation of
the parts.
One of the principal features of my invention consists in providing three series
of superimposed gears and pinions, all disposed upon an approximately right line,
the central series comprising the primary driving and the final driven member of
the train, and the two outer series of gears and pinions which mesh with the central
series in the manner hereinafter more particularly set forth.
It
I have shown my device as employed for speed reduction in which the driving
pinion is the high speed pinion, and the driven pinion is the low speed pinion, but
it is to be understood of course that the parts may be reversed, and the low speed
pinion may be the driving pinion, and the same advantageous results obtained.
will be observed that both the driving member and the driven member of the gear
train are contained in the central series of gears. Thus in the arrangement shown
the primary driving pinion 6 is fixed to a spindle 7, mounted on the lower plate 4,
and in the present instance this spindle has an arm or other means 8 by which it
is driven, as by the spindle C of the disc meter action D. The said pinion 6
meshes right and left with gears 9 and 10, having pinions 11 and 12 respectively
fixed thereto. These gears and pinions are free to revolve, being mounted
ID 017

page_text: upon the upright axles or spindles 13, 14, confined in the upper and lower
plates 3 and 4.
The next transmission is from the pinions 11 and 12 to the single lower centre
gear wheel 15, to which gear is fixed a pinion 16, and both the gear and pinion are
free to rotate on the lower extension 17 of the spindle 18 of the driven gear, the
collar or head 19 supporting the gear and pinion in proper position on the spindle.
Of course instead of mounting this gear and pinion on an extension of the driven
spindle it may be mounted on an extension of the driving spindle, or even
independently mounted, the main feature being that it is supported between the
driven and driving gears in a line with their axes.
The next transmission is from the single central pinion 16, right and left to the
two upper gear wheels 20, 21, to which wheels are respectively fixed the pinions 22
and 23, but both the gear wheels and pinions are freely mounted upon the upright
axles 13, 14, and in the present instance their weight is borne by the collars 24, 25,
fast to the axles.
The final transmission is from the two pinions 22, 23, acting right and left upon
the single upper centre gear 26 which is fixed to the driven spindle 18 in the
present instance, and thus becomes the final driven member of the train, it being
shown as passing through the stuffing box of the water meter casing. It is evident
that this same arrangement may be extended to a greater or less extent by adding
more pinions and gears arranged in substantially the manner set forth, so that any
amount of reduction or increase of speed may be attained.
From this arrangement of the parts it will be seen that no side thrusts are borne
by either the spindles or the bearings of the central series of the train, while the
side thrusts transmitted therefrom right and left to the two outer series are not
only materially reduced in intensity, but are borne and resisted by twice the
projected area that would be afforded by a single series.
Among the practical advantages arising from this construction and arrangement
are that whatever wear may take place both upon the high speed spindle, as 7, and
also in its bearing in the plate, it will be uniformly distributed, that is it will be
cylindrical, in contradistinction to the oblong wear or bearing produced by simple
single spur trains which cause the wear to take place chiefly in the direction of the
side thrusts. So also the same advantages apply with equal, if not greater, force
to the final driven member as the spindle 18, which is required to be revolved
against the greater frictional resistance of the stuffing box, for instance, besides
having to drive the exterior gearing of a register in the case of a water meter or
other apparatus in other cases, and is shown as provided with the gear 27 for this
purpose. Furthermore by thus compounding the train and thereby balancing the
strains upon the central series of gears, as will be seen more particularly by
reference to the diagrams Figs. 3 and 4, and doubling the working contacts, it
becomes feasible to considerably reduce the diameters of the axles supporting the
gears and pinions, and to use teeth of finer pitch and less breadth of face than
would be practical with a single train system.
Furthermore it is desirable in a construction like that described that the radial
location of the leaves of each pinion with respect to the teeth of the gear to which
it is fixed and with which it rotates shall be exactly similar to that of every other
gear and pinion. In other words if a line drawn through the leaves of one pinion
should pass through spaces of its gear, whilst the leaves of another pinion should
point towards the teeth of its gear, then the driving stresses would not be in balance,
and the teeth of the train, if accurately cut and located, would jam sidewise. The
construction and disposal here contemplated are clearly indicated in Fig. 2 showing
what may be said to be the initial setting up of the train, a leaf in each pinion and
two spaces in the gear all lying in the same right line B. In this wise the stresses
and resistances, as indicated in the diagrams Figs. 3 and 4, will be fully realized in
practice.
In the foregoing specification I have pointed out the general principles of my

page_text: invention and the results and advantages of the construction as well as the preferred
form of embodying it, and―
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A spur gear train, comprising a central series of superimposed gears and
pinions, and two outer series of superimposed gears and pinions meshing with the
central series, the axes of the various series being disposed in an approximately
right line, substantially as described.
2. A spur gear train, comprising a central series of superimposed gears and
pinions containing the primary driving member and the final driven member of the
train, and two outer series of superimposed gears and pinions meshing with the
central series, the axes of the several series being disposed in an approximately
right line, substantially as described.
3. A spur gear train, comprising a central series of gears and pinions, and two
outer series of gears and pinions disposed to the right and left and meshing
with the central series, and means for mounting said series, substantially as
described.
4. The combination with the upper and lower gear plates, of the axles supported
in said plates, the two outer series of gears and pinions mounted thereon, the driven
spindle mounted in one plate, and the driving spindle mounted in the other plate,
substantially as described.
5. The combination with the upper and lower gear plates, of the axles mounted
in the plates, the two outer series of gears and pinions loosely mounted thereon, the
driven spindle mounted in one plate and carrying the intermediate gear and pinion
loosely mounted thereon, and the driving spindle mounted in the other plate,
substantially as described.
Dated the 19th day of November 1901
PHILIP M. JUSTICE,
Chartered Patent Agent, 55 & 56, Chancery Lane, London,
For the Applicant.