A NEW CONSTRUC- TION OF ROTATORY ENGINES OR PUMPS
Year: 1854

page_text: LETTERS PATENT to Alexander Dalgety, of Florence Road, Deptford, in
the County of Kent, Engineer, for the Invention of "A NEW CONSTRUC-
TION OF ROTATORY ENGINES OR PUMPS."
Sealed the 8th March 1854, and dated the 19th January 1854.
PROVISIONAL SPECIFICATION left by the said Alexander Dalgety at the
Office of the Commissioners of Patents, with his Petition, on the 19th
January 1854.
I, ALEXANDER DALGETY, of Florence Road, Deptford, in the County of
Kent, Engineer, do hereby declare the nature of the said Invention for "A
NEW CONSTRUCTION OF ROTATORY ENGINES OR PUMPS" to be as follows:--
This Invention consists of a circular bored cylinder, having a piston rod or
shaft passed through its end cover, such rod or shaft being actuated eccen-
trically in the cylinder, or without the axial centre line of the same. The piston
rod has, keyed or otherwise secured to a metallic boss, which has its periphery
notched or cut away at certain places to receive one, two, or three, or more
rolling pistons corresponding in length to the internal length of the cylinder.
These pistons bear against the interior of the cylinder, and roll over a projecting

page_text: boss cast upon the interior of each cover. These bosses are made concentric
with the bore of the cylinder, and the diameter of the rolling pistons must
correspond exactly to the intermediate space between the periphery of the fixed
bosses and the inside of the cylinder. The end packing of the several rolling
pistons is composed of a conical split ring let into each end of such pistons, and
bearing against the internal faces of the covers. These rings being let into
conical seats, they tend, by their expansion, to force themselves outwards, and
so constitute an efficient packing against the covers. The steam or fluid, as
the case may be, is admitted at one side of the cylinder, and escapes or is
expelled at the other side. When in motion either as an engine or rotatory
pump no actual rubbing takes place between the pistons and the interior of the
cylinder, as the pistons revolve round their own axes, and roll over the surface
of the boss during the revolution of the main boss which carries them.
Another arrangement of rolling pistons consists in the application of a distinct
disc or wheel at each end of the roller, such discs or wheels being carried on
the ends of an internal spindle on to which the roller is keyed. These discs are
of exactly the same diameter as the rollers, but the sides of the notches or
recesses in the main carrying disc are cut away slightly, so that the wheels or
discs alone bear against the sides of the notches, whereby the decrease of friction
is obtained. The inequality of the sides of the notches may be compensated
for by suitable packing, if required. The fixed bosses are also cut away circum-
ferentially in such a manner that the wheels or discs above mentioned are
never in contact with them, the rollers alone bearing upon them. Another
modification of the same principle consists in connecting the rolling pistons
to the carrying disc, instead of sliding in notches by an arm working on a
fixed pin, so that as the carrying disc revolves, the arms and rollers adjust
themselves to the inside of the cylinder. The main shaft of the engine
in all cases being packed by any of the well-known existing arrangements,
it is proposed, if found desirable, to economise the waste or escape steam
by allowing it to escape from the periphery of a fly-wheel in connection
with the engine itself, whereby a certain additional amount of power may be
obtained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Dalgety in the Great Seal Patent Office on the
19th July 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
DALGETY, of Florence Road, Deptford, in the County of Kent, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Nineteenth day of January, in the year of our Lord One
thousand eight hundred and fifty-four, in the seventeenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alexand Dalgety, Her special license that I, the said Alexander Dalgety,
my executors, administrators, and assigns, or such others as I, the said
Alexander Dalgety, my executors, administrators, or assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "A NEW CON-
STRUCTION OF ROTATORY ENGINES OR PUMPS," upon the condition (amongst
others) that I, the said Alexander Dalgety, 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 Alexander Dalgety, 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, 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 improved construction and arrangement of
the cylinder covers and pistons of rotatory engines and pumps, and consists in
the employment of a circular bored cylinder, having a piston rod or shaft passed
through its end covers, such rod or shaft being situated eccentrically in the
cylinder, or without the axial centre line of the same. The piston rod has,
keyed or otherwise secured to it, a metallic boss, which has its periphery notched
or cut away at certain places to receive one, two, three, or more rolling pistons
corresponding in length to the internal length of the cylinder. These pistons
bear against the interior of the cylinder, and roll over a boss cast upon or

page_text: attached to the interior of each cover. These bosses are made concentric with
the bore of the cylinder, and the diameter of the rolling pistons must correspond
exactly to the intermediate space between the periphery of the fixed bosses and
the inside of the cylinder. The end packing, when a rolling piston or pistons
are applied of the several rolling pistons, may be composed of a conical split
ring let into each end of such pistons, and bearing against the internal faces of
the covers. These rings being let into conical seats, they tend, by their expan-
sion, to force themselves outwards, and so constitute an efficient packing
against the covers. The steam or fluid, as the case may be, is admitted at
one side of the cylinder, and escapes or is expelled at the other side. When
in motion, either as an engine or rotatory pump, no actual rubbing takes place
between the pistons and the interior of the cylinder, as the pistons revolve
round their own axes, and roll over the surface of the boss during the revolu-
tion of the main boss which carries them. Another arrangement of rolling
pistons consists in the application of a distinct disc or wheel at each end of the
roller, such discs or wheels being carried on the ends of an internal spindle
on to which the roller is keyed. These discs are of exactly the same diameter
as the rollers, but the sides of the notches or recesses in the main carrying disc
are cut away slightly, so that the wheels or discs alone bear against the sides
of the notches, whereby a decrease of friction is obtained. The inequality of the
sides of the notches may be compensated for by suitable packing, if required.
The fixed bosses are also cut away circumferentially in such a manner that the
wheels or discs above mentioned are never in contact with them, the rollers
alone bearing upon them. Another modification of the same principle of
pistons consists in connecting the rolling pistons to the carrying disc instead of
sliding in notches, by an arm working on a fixed pin, so that as the carrier disc
revolves, the arms and rollers adjust themselves to the inside of the cylinder.
The main shaft of the engine in all cases being packed by any of the well-
known existing arrangements, it is proposed, if found desirable, to economise
the water or escape steam by allowing it to escape from the periphery of a fly-
wheel.in connection with the engine itself, whereby a certain additional amount
of power may be obtained. Figure 1, on my Sheet of Drawings, represents a
transverse vertical section of my improved rotatory engine or pump with rolling
pistons applied; Figure 2 is a corresponding longitudinal vertical section of the
same; Figure 3 is a detail side elevation of one of the end covers of the
cylinders, showing the projecting boss herein-before referred to; Figure 4 is a
corresponding vertical section of the same; Figure 5 is a side elevation of
another modification of piston; and Figure 6 is a corresponding longitudinal
vertical section of the same. A, A, is a circular bored cylinder, the piston rod

page_text: or shaft B of which is passed through and works in stuffing boxes in the end
covers C, C. This rod or shaft is situated eccentrically in the cylinder, or
without the axial centre line of the same, such eccentricity being either in a
vertical direction, as shewn in my Drawings, or in any other direction as found
most desirable or convenient. A metallic boss D is keyed or otherwise secured
to the piston rod, and the periphery of this boss is notched or cut away at E, E,
to receive the three rolling pistons F, F, F", which correspond in length to
the internal length of the cylinder. Although I have represented three rolling
pistons in Figure 1 of my Drawings, yet I by no means confine or restrict
myself to that number, as a greater or less number of pistons may be employed,
the revolving boss D being of course notched accordingly. The pistons F
consist of rollers or cylinders of brass, cast-iron, or other suitable metal, which
may be open throughout their length, and bearing or resting at their extremi-
ties upon the projecting circular bosses G, G, which are cast upon or attached
to the internal faces of the two end covers C. These bosses are made con-
centric with the bore of the cylinder, and the diameter of the pistons F must
correspond exactly to the intermediate space between the periphery of the fixed
boxes G and the inner circumference of the cylinder, as is clearly represented
at Figure 1 of my Drawings. The ends of the pistons rub over the inner
faces of the cylinder covers, and may be packed, if found desirable, by any
suitable end packing. I propose in some cases to employ for the end packing
of the rolling pistons, as shewn in Figure 1, a conical split ring which is
inserted into an annular groove or recess in the ends of the pistons, as I have
herein-before described, such rings bearing against the faces of the covers, and
held in contact therewith by the action of their expansive force tending to press
them outwards against the internal faces of the covers, thereby constituting
an efficient end packing. The ends of the revolving boss D may also be
packed, if found desirable, by any suitable end packing, such, however, form-
ing no portion of my present Invention. The steam or fluid, as the case may be,
is admitted at the passage H, and escapes or is expelled through the passage I
on the opposite side of the cylinder. On steam being admitted into the cylinder
it exerts a certain amount of pressure against the pistons F and F', but as the
piston F is farthest from the centre of the piston rod or shaft B, and conse-
quently offers the greatest leverage, it follows that the boss D will revolve in
the direction of the arrow, as shewn in the Drawings, the several pistons
(although passing through unequal and ever-varying diameters) being kept in
easy yet close contact with the internal surface of the cylinder by the action of
the fixed bosses G, G, on the cylinder covers. Before proceeding to describe
the second modification of piston,. illustrated by Figures 5 and 6 on the accom-

page_text: panying Sheet of Drawings, I may observe that I do not confine or restrict
myself to any particular form of piston or pistons, or of the packing thereof,
as various modifications of either rolling or sliding pistons may be found appli-
cable in connection with the aforesaid two fixed bosses or internal projections,
and piston shaft passed eccentrically through them. The arrangement I shall
now proceed to describe consists of a sliding piston in place of the rolling ones
shewn at Figure 1. The revolving or carrying boss A corresponds to the
boss D in Figure 1, and is keyed or otherwise secured to the piston rod or
shaft B. The pistons C, C, consist of one, two, or more slides shaped like a
roller, with the two opposite sides cut away or flattened so as to work in close
but easy contact with the sides of the notches in the boss A. The diameter of
these flattened rollers must correspond, as herein-before described, to the
distance between the periphery of the fixed bosses on the end covers and the
internal surface of the cylinder shewn by the red lines in Figure 5. D, D, are
shanks, which may be cast on or attached to the slides C, their use being
to give strength and steadiness to each other, as when one is projecting
beyond A, A, as shewn in Figure 5, it is still supported and kept firm by the
other which is within. These shanks are slotted at E to receive the piston rod
B, and are thereby free to expand or contract according to the varying diameter
through which they have to traverse. The shanks overlap each other, and
their ends project into recesses F formed in the slides C, as shewn in the
Drawing, one end of each slide or piston being shewn in section, to illustrate
more clearly the overlapping of the shanks and the recesses F. The length of
the pistons or slides C, as well as the boss A, must correspond to the length
of the cylinder, and their ends may be packed with any suitable end packing.
The pistons or slides C rest upon the fixed bosses of the cylinder covers
at the points marked G, in Figure 6, the ends of the pistons being made
to project or overhang slightly for that purpose.
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 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 said 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 rotatory engines or
pumps, as herein-before described.
Second, the application and use of a boss or internal projection, (concentric

page_text: with the bore of the cylinder,) cast upon or secured to the inner face of each
cylinder cover, the piston rod or shaft being passed through and worked
concentrically to such concentric bosses or internal projections, such arrange-
ment affording facility for using one sliding or rolling piston only, if found
desirable.
In witness whereof, I, the said Alexander Dalgety, have hereunto set
my hand and seal, the Nineteenth day of July, in the year of our
Lord One thousand eight hundred and fifty-four.
A. DALGETY. (L.S.)