INPROVEMENTS IN STEAM ENGINES
Year: 1853

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, and of Glasgow, North
Britain, Gentleman, for the Invention of "INPROVEMENTS IN STEAM
ENGINES" A communication
PROVISIONAL SPECIFICATION left by the said John Henry
Johnson at the Office of the Commissioners of Patents, with his
Petition, on the 18th March 1853.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, and of Glasgow, North Britain, Gentleman, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN STEAM
ENGINES" to be as follows:-
This Invention is for the purpose of obviating the constant jarring
and undue straining of the crank shaft, engine framing, and vessel hull,
in marine and other engines, whether oscillating or not. This is ac-
complished by an improved arrangement of cranks on the main shaft.
If the engine is intended to drive a screw propeller, the cylinders are

page_text: arranged on each side of the main shaft, which is driven direct, without
any intermediate gearing. In oscillating cylinder engines, one cylin-
der contains two piston rods, which are connected with the same piston,
and are attached at their opposite ends to a pair of cranks on the main
driving shaft.
These cranks are, however, sufficiently far apart to
afford space for a third crank between them, which may be set in the
same plane with the other two, or at a slight angle, if requisite, but
To this centre crank
projecting from the opposite side of the shaft.
is attached the end of the piston rod of the other cylinder, which is
The working
fitted with a piston and rod in the ordinary manner.
of the slides may be effected by any convenient arrangement, accord-
ing to circumstances. By the above arrangement it will be seen that
the strain of one piston is neutralized or counteracted by the other, as
they both act in different directions, and have their cranks so arranged
ns to prevent any tondancy which the pistons may have to displace the
shaft from its bearings. This admits of the engine being worked at a much
greater speed than can otherwise be obtained by means at present in use.
shaft from its bearings. This admits of the engine being worked at a much
greater speed than can otherwise be obtained by means at present in use.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson, in the Great Seal Patent
Office, on the 17th September 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of Glasgow, North Britain, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of March, in the year
of our Lord One thousand eight hundred and fifty-three, in the six-
teenth year of Her reign, did, for Herself, Iler heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
licence, that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during

page_text: the term therein expressed, should and lawfully might make, use, exer-
cise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IM-
PROVEMENTS IN STEAM ENGINES," being a communication to me from a
foreigner resident abroad, upon the condition (amongst others) that I,
the said John Henry Johnson, 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 John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained 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:
The said Invention relates to a peculiar arrangement of the cranks
of marine or other engines, whereby the great lateral strain upon the
bearings of the main shaft, as well as the injurious vibratory or tremu-
lous movement of the machinery, is obviated. This is effected by
placing the cranks on the main shaft diametrically opposite each other,
and thus neutralizing the strain or lateral pressure of the piston or
connecting rods against the main shaft.
Figure 1, of the accompanying sheet of drawings represents a transverse
section of a vessel through the propeller shaft, shewing the engines in
side elevation; and Figure 2, is a corresponding plan of the same, shew-
ing the general arrangement of the two pairs of engines. The crank or
propeller shaft A, is situated between the cylinders C, C', and is formed
into three successive cranks, all of which are in the same plane, but ar-
ranged in such a manner that the middle one a, is diametrically opposite
to the other two a', a'. The centre crank is connected with the head of
the piston rod B, of one of the cylinders, whilst the outside cranks a', a'
are connected with the opposite piston rods B, B', which are fitted into the

page_text: piston of the second cylinder. The valve gearing, which I have not
considered necessary to show in the drawings, may be worked by any of
the well known methods adopted in marine engines of this class, and
so arranged that the pistons shall move in precisely opposite directions.
Supposing the crank shaft to be revolving in the direction indicated by
the arrow in Figure 1, the rod B, of the right-hand cylinder will ad-
vance in the direction indicated on the drawing, at the same time that
the two other piston rods B, B, of the left-hand cylinder traverse in
the contrary direction. Thus, the crank pin a, is pushed from right to
left, while the other two a', a', will be propelled in the contrary direc-
tion, or from left to right. Thus, when the latter approach the
extremity of their stroke, they no longer produce those injurious reac-
tionary shocks herein-before mentioned; since, whatever may be the
weight or speed of the cranks, the reaction will be entirely neutralized
by the opposite one, as at the same time that one piston approaches the
top of one cylinder the other piston approaches the bottom of the oppo-
site cylinder. During the return stroke, the pistons assist each other,
also, until they arrive at the opposite end of their traverse, all reac-
tionary force being obviated. It will thus be seen that an equilibrium
of pressure is exerted against the main bearings of the shaft A. since
the pressure on each side is the same throughout its entire revolution.
This effect is produced during the entire traverse of the piston, as they
constantly occupy the same relative positions in each of their respective
cylinders, but in different directions. In thus obtaining an equal pres-
sure on each side of the main shaft, it follows that its bearings will be
much less strained, and consequently that the friction will be greatly
reduced, thereby effecting a saving in lubricating material, and obviat-
ing the shaking of the framework, so injurious to its stability. The
number of revolutions may also be greatly increased without much
inconvenience, as a greater regularity is obtained in the working of the
engines. In the construction of engines of four cylinders, the two
shafts A, A, if of large dimensions, may be coupled, as at M, between
the two pairs of cylinders. To eflect the working of the air-
pumps C, C', two cranks b, b', are formed on the main shaft; care

page_text: being taken that they be in diametrically opposite positions also, as
shewn in the plan view, Figure 2. Thus the pressure of these two
pistons is also neutralized; tending, as before described, to reduce the
friction and straining of the main bearings. Although the air-
pumps C, C, are represented as placed between the two engines in the
drawing hereunto annexed, yet they may with equal convenience and
facility be placed outside the engines, which in such case would be
brought nearer together, and would probably occupy less space. It will
be obvious to the practical engineer that this arrangement of cranks is
equally applicable and serviceable to engines with either vertical or
horizontal cylinders, such cylinders being either fixed or oscillating;
since the use of connecting rods and guides does not interfere in any
way with the peculiar arrangement of cranks herein-before described.
When four cylinders are employed, as shewn in the drawing, the cranks
of one pair of cylinders are placed at right angles with the cranks of
the second pair; thereby producing a perfect regularity of movement
with a great velo cty of working, whether the engine be required for
the screw propeller or for manufacturing purposes. Should the engine
be a single one, or of two cylinders only, they may be made of equal
diameter, receiving, each of them, their steam direct from the boiler, as
illustrated in the drawings. Or, they may be arranged as in the Woolff
engine; namely, one of the cylinders only (the smaller one) receiving
its steam direct; giving it afterwards to the larger cylinder, after actua-
ting the piston of the first one. The cranks may be so arranged as to
form a certain angle between them, more or less obtuse, in place of
being diametrically opposite each other.
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 I do not confine
or restrict myself to the presise details or arrangements which I have had
occasion to describe or refer to, as many variations may be made there-
from without deviating from the principles or main features of the said
Invention; but what I consider to be new and original, and therefore
claim as the Invention secured to me by the herein-before in part
recited Letters Patent, is,-

page_text: The system or mode of constructing crank shafts with the cranks in
the same plane, or nearly so, for the purposes herein-before described.
In witness whereof, I, the said John Henry Johnson, have here-
unto set my hand and seal, this Thirteenth day of September,
in the year of our Lord One thousand eight hundred and fifty-
three.
J. HENRY JOHNSON. (L.S.)