IMPROVEMENTS IN MACHINERY OR APPARATUS FOR TRANSMITTING MOTIVE POWER.
Year: 1856

page_text: LETTERS PATENT to Robert Struthers, of Holyhead, in the County of
Anglesea, Engineer, for the Invention of "IMPROVEMENTS IN MACHINERY
OR APPARATUS FOR TRANSMITTING MOTIVE POWER.
Sealed the 16th January 1857, and dated the 24th October 1856.
PROVISIONAL SPECIFICATION left by the said Robert Struthers at tho
Office of the Commissioners of Patents, with his Petition, on the 24th
October 1856.
I, ROBERT STRUTHERS, of Holyhead, in the County of Anglesea, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
MACHINERY OR APPARATUS FOR TRANSMITTING MOTIVE POWER," to be as follows,
that is to say:-
This Invention relates to an arrangement of toothed-wheel gearing, especially
adapted for communicating the motion of the engine to the screw propeller in
screw steamers, but which arrangement is also applicable in other situations
and for other purposes where motive power is to be transmitted from one shaft
to another. As adapted for driving the screw propeller, the end of the engine
or driving shaft has keyed upon it a crank arm or a disc plate with a crank
pin in its outer face. The crank pin of this crank or disc runs loose in its
retaining bearing, and it has keyed upon it a spur pinion, which is in gear
externally with an internally-toothed spur wheel, held stationary in a vertical
position by the framing, whilst internally it gears with a corresponding toothed
pinion, which is keyed fast on the screw propeller shaft.
The screw propeller shaft is disposed with its axis in line with that of the
driving shaft, so that externally the two shafts appear to be in one length, the
end of the driving shaft being bored out to admit the corresponding junction
end of the driven or screw propeller shaft. As the driving shaft revolves, the

page_text: crank arm pinion is obviously carried round the driving shaft's centre at the
same rate of revolution upon this centre as the shaft itself; but being in gear
on one side with the fixed internally-toothed ring or wheel, and on the other
with the second pinion on the driven shaft, it follows that a differential relative
action ensues. The crank arm pinion in revolving round the centre of its
shaft is also made to revolve independantly upon its own centre at each turn of
the driving shaft as many times, less one, as its number of teeth are contained
in the number of teeth in the fixed external wheel, and as this crank arm
pinion is also in gear with another pinion upon the driven shaft, it follows
that the latter is made to revolve just as much faster than the driving shaft
as is determined by the relations between the numbers of teeth in the crank
arm pinion, and those in the fixed internal wheel: This is on the supposition
that the two pinions have equal numbers of teeth, in which case the driven
shaft makes as many revolutions during-one of the driving shaft as "are equal
to one more than the number of times the teeth of the pinion is contained in
those of the fixed internal wheel. The pinions, however, may be of different
sizes, so as to produce a further difference in the relative velocities. An
increased speed-multiplying effect may be produced by making-the wheel
carried' round by the crank a double wheel, that is, having a small ring of teeth
gearing with the teeth of the fixed internal wheel, and a larger ring of teeth
gearing with a pinion on the driven shaft. If a disc crank is used, the whole
of the details can be securely boxed up by attaching to it, a corresponding
plain disc reversed, and carried..upon the driven shaft as a centre, the space
between the two discs being sufficient to receive the width of the gearing,
whilst the stationary internally-toothed ring closes up the periphery of the
combination of discs. This second disc also answers for furnishing a bearing
for the outer end of the crank pin.of.the, crank arm pinion... The relative
proportions of the teeth in these wheels may be variously modified as, may, be
required for different proportions of speeds, and advantage may obviously.be
taken of the movement for either reducing; or increasing speed, the driving
and driven shafts always being in the same axial line.
•

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of October, in the year of our Lord
One thousand eight hundred and fifty-six, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Robert Struthers, Her special license that I, the said Robert Struthers,
my executors, administrators, and assigns, or such others as I, the said
Robert Struthers, my executors, administrators, or assigns, should at any time
agree with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
MACHINERY OR APPARATUS FOR TRANSMITTING MOTIVE POWER," upon the con-
dition (amongst others) that I, the said Robert Struthers, by an instrument
in writing under my hand and seal, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Robert Struthers, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say:-
My said Invention relates to an arrangement of toothed-wheel gearing,
especially adapted for communicating the motion of the engine to the screw
propeller in screw steamers, but which arrangement is also applicable in
other situations and for other purposes where motive power is to be trans-
mitted from one shaft to another. As adapted for driving the screw propeller,
the end of the engine or driving shaft has keyed upon it a crank arm or
disc plate with a crank pin in its outer face. The crank pin of this crank or
disc runs loose in its retaining bearing, and it has keyed upon it a spur pinion,
which is in gear externally with an internally-toothed spur wheel, held stationary
in a vertical position by the framing, whilst internally it gears with a cor-
responding toothed pinion which is keyed fast on the screw propeller shaft.
The screw propeller shaft is disposed with its axis in line with that of the
driving shaft, so that externally the two shafts appear to be in one length, the
end of the driving shaft being bored out to admit the corresponding junction
end of the driven or screw propeller shaft. As the driving shaft revolves, the
crank arm pinion is obviously carried round the driving shaft's centre at the

page_text: same rate of revolution upon this centre as the shaft itself, but being in gear
on one side with the fixed internally-toothed ring or wheel, and on the other
with the second pinion on the driven shaft, it follows that a differential
rotative action ensues. The crank arm pinion in revolving round the centre
of its shaft is also made to revolve independently upon its own centre at each
turn of the driving shaft as many times, less one, as its number of teeth are
contained in the number of teeth in the fixed internal wheel, and as this
crank arm pinion is also in gear with another pinion upon the driven shaft, it
follows that the latter is made to revolve just as much faster than the driving
shaft as is determined by the relations between the numbers of teeth in the
crank arm pinion and those in the fixed internal wheel. This is on the
supposition that the two pinions have equal numbers of teeth, in which case
the driven shaft makes as many revolutions during one of the driving shaft as
are equal to one more than the number of times the teeth of the pinion is
contained in those of the fixed internal wheel; the pinions, however, may
be of different sizes, so as to produce a further difference in the relative
velocities. An increased speed-multiplying effect may be produced by making
the wheel carried round by the crank a double wheel, that is, having a small
ring of teeth gearing with the teeth of the fixed internal wheel, and a larger
ring of teeth gearing with a pinion on the driven shaft. If a disc crank is
used, the whole of the details can be securely boxed up by attaching to it a
corresponding plain disc reverved, and carried upon the driven shaft as a
centre, the space between the two discs being sufficient to receive the width
of the gearing, whilst the stationary internally-toothed ring closes up the
periphery of the combination of discs. This second disc also answers for
furnishing a bearing for the outer end of the crank pin of the crank arm
pinion. The relative proportions of the teeth in these wheels may be variously
modified as may be required for different proportions of speeds, and advantage
may obviously be taken of the movement for either reducing or increasing
speed, the driving and driven shafts always being in the same axial line.
And in order that my said Invention may be properly understood, I shall
now proceed to describe the several illustrative Figures on the explanatory
Sheet of Drawings which I have hereunto appended, for the purpose of show.
ing certain modifications under which my improvements may be judiciously
carried out in practice.
Figure 1 on my Sheet of Drawings is a partially sectional longitudinal
elevation of the after part of a ship as fitted with a screw propeller, having
my improvements applied thereto. Figure 2 is a transverse section of a vessel,
the sectional line being taken forward of the engines, or towards the vessel's

page_text: bow. Figure 3 is an elevation of one modification of my improved gearing
for increasing the speed or number of revolutions of screw propeller shafts.
In this Figure one of the disc plates is removed to show the internal arrange-
ment of the mechanism. Figure 4 is a partially "sectional elevation of the
movement, corresponding to Figure 3. In the modification of my improve-
ments, as shown in the illustrative Figures 1 and 2 of my Sheet of Drawings,
the main crank driving shaft A is represented as being driven by a pair of
direct-action engines. The cylinders. of the engines are supported over head
upon vertical side standards B, which are curved or bowed outwards at the
lower part to admit of the rotation of the cranks C. The lower ends of
the piston rods work in guides fitted inside the vertical portion of the
standards B, and are connected by the rods D to the crank C on the driving
shaft A.
My improved compound gearing is supported or contained within the
framing E, and, as shown in Figure 1, the propeller shaft F is in a direct
axial line with the driving shaft, so that externally the two shafts appear as
one. This is effected by boring out the end of the driving shaft A so as to
receive the end of the propeller shaft F, the one revolving within the other.
The driving shaft A has keyed to it the disc plate or crank disc G, which
consequently rotates with the shaft, and another disc plate H is bolted to the
propeller shaft F by the bolts and nuts I. These disc plates fit within the
periphery of the circular part of the framing, and serve to protect the internal
gearing from injury, as well as to screen the attendants from entanglement.
A crank pin J passes through the disc plates G and H from side to side, and
rotates freely in bearings therein, and upon this crank pin a spur pinion K is
keyed. The pinion K is in gear with the stationary annular or internally-
toothed wheel L, which forms a part of the fixed framing E, being held in a
vertical position by the framing E; the pinion K is also in gear with the
pinion M, which is keyed to the propeller shaft F. By means of this arrange-
ment, when a rotatory motion is given to the driving shaft it carries with it
the disc plates G and H and the crank pin J, which causes the pinion K to
rotate within the annular wheel L. The pinion K being also in gear with
the pinion M, on the propeller shaft F, the speed of the latter is increased
according to the difference between the number of teeth on the crank arm
pinion K and those in the fixed annular or internally-toothed wheel L, as
before explained in the first part of this Specification.
Another modification of this my improved arrangement of compound
gearing consists in using a crank keyed to the driving shaft, and carrying at
its outer end a spur pinion in gear with the internally-toothed wheel, and with

page_text: :
a pinion in the driven shaft. In this arrangement the disc plates which
enclose the annular wheel are dispensed with.
Another modification of the improved compound gearing consists in so
arranging the relative proportions of the crank arm pinion and that on the
driven shaft, as to reduce the speed of the driven shaft instead of increasing it,
as in the arrangement shown in Figures 3 and 4 of my Sheet of Drawings.
The facility with which these differential speeds may be obtained or altered to
suit the particular purpose for which it is desired renders these combinations
of compound gearing of great use to the practical engineer, and applicable to
a variety of purposes in mechanical arrangements.
:
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention; but what
I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,
First, the general arrangement and construction of compound gearing, as
herein-before described.
Second, the system or mode of increasing the speed of screw propeller
shafts by means of compound gearing, as herein-before described.
Third, the system or mode of increasing the speed of screw propeller shafts
by the agency of a toothed pinion driven by the first motion shaft, whilst it
gears both with a stationary internal-toothed wheel and a pinion upon the
propeller shaft.
Fourth, the system or mode of increasing or diminishing the speed of shafts
or other rotatory parts of machinery by means of compound gearing, as
herein-before described.
In witness whereof, I, the said Robert Struthers, have hereunto set my
..hand and seal, this Twenty-first day of April, One thousand eight
hundred and fifty-seven...