Improvements in Combinations of Spur Gearing for Reducing Motion.
Year: 1884

page_text: Improvements in Combinations of Spur Gearing for Reducing
Motion.
We TOM MILBURN and CHARLES WILLIAM HAYDON of the firm of William
Milburn and Sons of the Britannia Foundry Staley bridge in the County of
Lancaster Iron Founders and EDWARD MUNDY in the employment of the said firm
Mechanic do hereby declare the nature of the said invention for "IMPROVEMENTS
IN COMBINATIONS OF SPUR GEARING FOR REDUCING MOTION " to be as follows:-
Our Invention relates to the combinations of gearing used in machinery or in
mechanical movements to reduce the speed or number of revolutions in transmitting
rotatory movement, or to state it otherwise to convert speed into power and the
principal object of our invention is to obtain this reduction by a simple and
compact combination of gearing. In a combination constructed in accordance with
our Invention we use two internal spur wheels and two ordinary or external
wheels the two latter being formed in one piece or secured together and mounted
to revolve upon an axis which is excentric to the axis of the internal wheels and
which can revolve around the last named axis. The wheels vary in the numbers
of teeth one internal wheel having one two or more teeth less than the other and
the external wheels having a corresponding difference. When motion is transmitted
through the intermediate couple of external wheels from one internal wheel to the
other the speed is greatly reduced. The motion may also be transmitted by fixing
one of the internal wheels and applying the power to carry the axis of the inter-
mediate external wheels around the cominon axis of the internal wheels. The
combination forms a very compact arrangement of gearing not requiring counter-
shafts and the spur wheels are small as compared with the reduction of speed
effected or with the speed converted into power. An advantage for some uses is
that the whole of the gearing is or may readily be enclosed. The combination
may be extended for some purposes by making the driven internal wheel the
driver of another series of internal and external wheels so that the gearing requisite
for effecting any ordinarily required reduction of speed may be arranged within a
small compass.
EDWARD K. DUTTON,
41, John Dalton Street, Manchester,
Agent.

page_text: COMPLETE SPECIFICATION.
Improvements in Combinations of Spur Gearing for Reducing
Motion.
We Toм MILBURN and CHARLES WILLIAM HAYDON of the firm of William
Milburn and Sons of the Britannia Foundry Staleybridge in the County of
Lancaster Iron Founders and EDWARD MUNDY in the employment of the said
firm Mechanic do hereby declare the nature of the said Invention for " IMPROVE-
MENTS IN COMBINATIONS OF SPUR GEARING FOR REDUCING MOTION and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement and accompanying drawings :-
"
Our Invention relates to the combinations of gearing used in machinery or in
mechanical movements to reduce the speed or number of revolutions in transmitting
rotatory movement or to state it otherwise to convert speed into power and the
principal object of our invention is to obtain this reduction by a simple and
compact combination of gearing. In a combination constructed in accordance with
our Invention we use two internal spur wheels and two ordinary or external
wheels the two latter being formed in one piece or secured together and mounted
to revolve upon an axis which is excentric to the axis of the internal wheels and
which can revolve around the last named axis. The wheels vary in the numbers
of teeth one internal wheel having one two or more teeth less than the other and
the external wheels having a corresponding difference.
In the accompanying drawings Fig. 1 represents a Vertical Section of a combi-
nation of gearing for transmitting and increasing power and Fig. 2 is a Cross
Sectional View of the same the upper half of the section being taken on the line A.
in Fig. 1 and the lower half on the line B in the same Fig. In the said Figs. a. is
a strap pulley which receives motion which is to be transmitted at a reduced speed
to the shaft b. Upon the said shaft is loosely mounted an excentric c. and the
pulley a. is fixed upon a tube d. which is formed upon the said excentric. Upon
the said excentric are loosely mounted two spur-wheels e. and f. which are cast or
formed together or are separately formed and are fixed together. The smaller
wheel gears with an internal spur wheel g. which is kept from revolving by
being attached to a fixed part in any suitable manner. The larger wheel f. gears
with a second internal wheel h. which is fixed upon the shaft b. In the example
the wheels e. and g. and the wheels f. and h differ in size to the extent of two teeth
the wheels e. and f. having the same difference. The excentric c. is revolved upon
the axis of the shaft by means of the pulley a. and carries the wheels e. and f
around the said axis the pitch line e. rolling upon the pitch line of the wheel g. It
will be seen that the wheel e. will make a little more than one revolution upon the
excentric whilst making one complete revolution around the axis of the shaft b.
The wheel f. is also maintained in rolling gear with the wheel h and if the
wheels e. and f. were of the same diameter no movement would be imparted to the
wheel h. but as the circumferential speed of the wheel f. is greater than that of
the wheel e. a slow movement is imparted to the wheel h. and as a consequence to
the shaft b. This movement of the wheel h may be calculated by dividing the

page_text: pitch line circumference of the said wheel by the difference between the excess of
circumferential movement of the wheel f. and that of the wheel e. over a complete
revolution for each complete revolution of the excentric. The gearing illustrated
is designed to impart one revolution to the shaft for ninety-nine revolutions of the
pulley a. the wheels c and g. having 18 and 20 teeth and the wheels f. and h 20
and 22. For one revolution of the excentric the wheel e. will revolve one and one
ninth times. The difference between one ninth of the circumference of the wheel e.
and one ninth of the circumference of the wheel f. will be the divisor for the
circumference of the wheel h. By varying the proportions of the wheels a
reduction of speed greater or less than ninety-nine to one may be obtained.
Motion could be transmitted by attaching the pulley a to the wheel g. in which
case the said pulley would have no connection with the excentric. The combination
forms a very compact arrangement of gearing not requiring counter-shafts and the
spur wheels are small as compared with the reduction of speed effected or with the
speed converted into power. An advantage for some uses is that the whole of
the gearing is enclosed but the entire enclosure indicated in the example may be
departed from. The combination may be extended for some purposes by making
the driven internal wheel the driver of another series of internal and external
wheels so that gearing requisite for effecting any ordinary required reduction of
speed may be arranged within a small compass Fig. 2 in the drawings is furnished
as an example of one of the applications of the combination of gearing. In this
example the said gearing is used in the formation of blocks or apparatus for raising
heavy weights the chain or rope pulley a corresponding to the pulley a. in Fig. 1.
The other corresponding parts of the gearing are marked with the same letters of
reference as in Fig. 1. The wheel h. is formed with a chain pulley i. for raising
the load and the wheel g. with a chain pulley k. for holding the said wheel by
connecting with the load a chain passed over the pulley k. in a reverse way to the
chain which passes over the pulley i. but any other suitable method may be
adopted for effecting this object as we make no claim in respect of these pullies.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is
1. The combination of gearing substantially as and for the purposes set forth
and indicated with reference to Fig. 1 of the accompanying drawings.
2. In gearing for reducing speed or gaining power two external spur wheels
differing in the numbers of their teeth mounted to revolve upon an excentric or
excentrical axis in gear with two internal spur wheels having a corresponding
difference the axis of the external wheels revolving or being revolved around the
common axis of the said internal wheels so as to cause the pitch lines of the
external wheels to roll upon the pitch lines of the internal wheels substantially as
set forth and indicated.