IMPROVEMENTS IN ENGINES ACTUATED BY STEAM OR COMPRESSED AIR FOR PUMPING AND FOR OTHER PURPOSES
Year: 1875

page_text: LETTERS PATENT to George Alfred Bridgett, of the City of Manchester,
Engineer, for the Invention of "IMPROVEMENTS IN ENGINES ACTUATED
BY STEAM OR COMPRESSED AIR FOR PUMPING AND FOR OTHER PURPOSES."
Sealed the 26th October 1875 and dated the 28th August 1875.
PROVISIONAL SPECIFICATION left by the said George Alfred Bridgett
at the Office of the Commissioners of Patents, with his Petition,
on the 28th August 1875.
I, GEORGE ALFRED BRIDGETT, of the City of Manchester, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
ENGINES ACTUATED BY STEAM OR COMPRESSED AIR FOR PUMPing and for otHER
PURPOSES," to be as follows :—
This Invention refers principally to direct-acting steam pumping
engines, and consists of an improved arrangement of supplementary
ports to distribute steam to work the slide valve without the use of a
long piston, supplementary valves, or tappets; also of an improved
metallic stuffing box, and in an improved general arrangement of com-
pound pumping engines.

page_text: both pistons are on one rod, and one steam moved slide valve controls
the flow of steam to and from both cylinders.
This Invention is also applicable to engines worked by compressed
air.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George Alfred Bridgett in the Great Seal Patent
Office on the 25th February 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
ALFRED BRIDGETT, of the City of Manchester, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of August, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said George Alfred Bridgett, Her special
licence that I, the said George Alfred Bridgett, my executors, admini-
strators, and assigns, or such others as I, the said George Alfred Bridgett,
my executors, administrators, and 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,
usc, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN ENGINES ACTUATED BY STEAM OR COMPRESSED AIR FOR
PUMPING AND FOR OTHER PURPOSES," upon the condition (amongst others)
that I, the said George Alfred Bridgett, my executors or admini-
strators, by an instrument in writing under my, or their, or one of
their hands and seals, 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 George Alfred Bridgett, do hereby

page_text: is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say) :-
This Invention refers principally to direct-acting steam pumping
engines, but it may be applied to other engines actuated by steam or
compressed air, and it consists, first, of an improved arrangement of
supplementary ports and passages to distribute steam to work the slide
valve without the use of a long piston, supplementary valves, or tappets;
secondly, in an improved general arrangement of compound pumping
engines; and thirdly, of an improved metallic stuffing box.
And in order that my Invention may be fully understood and readily
carried into operation I will proceed to describe the accompanying
Sheet of Drawings, in which Fig. 1 is a plan, Fig. 2 a longitudinal'
section, and Fig. 3 a transverse section of a pumping or other engine to
which the first improvements above referred to are applied.
a is the cylinder; b, the piston; c, the piston rod; d, the admission
pipe for the steam or compressed air; and e, the pipe for the exhaust.
The slide valve f is cylindrical, and has two supplementary ports and
passages f, f, leading from one of its sides to its respective ends. The
two supplementary ports in the side of the valve work against the threo
supplementary ports 9³, 92, and g³ in the side of the valve casing g. A
passage from the centre port g³ in the valve casing g leads to the exhaust
pipe e, and from the other two ports or passages g', 9%, to the ports a¹, a³,
in the respective ends of the main cylinder a.
I wish to remark that the passages 9' and f¹ instead of being on the
same side of the valve as the passages g² and få might be placed at the
opposite side of the valve; in this case an additional supplementary
exhaust port corresponding to g³ would be required. Both ends of the
valve are always open to the exhaust pressure, except at the instant
when the piston uncovers the auxiliary port at the end of the cylinder,
towards which it is moving.
The mode of operation is as follows:-The slide valve ƒ being at
the right-hand end of its traverse, as shewn in Figs. 1 and 2, the
passages f, g, and a² give communication between that end of the
valve and the corresponding end of the main cylinder a, and the
passages f¹ and 9 give communication between the other end of
the valve and the exhaust, the other passage g¹ in the valve casing

page_text: being closed. On the piston passing the passage a² in the cylinder steam
rushes to the right-hand end of the valve ƒ and moves it towards the
left-hand end of its casing, and so causes the piston 6 to commence
travelling in the opposite direction. This movement of the valve shuts
the communication between the cylinder and the end of the valve on
which the steam acted, and opens it to the exhaust. It also opens the
other end of the valve to what has then become the exhaust side of
the piston. On the piston passing the end of the other passage a¹ in the
cylinder the reverse action takes place. To prevent the valve f striking
against the covers of the valve casing g a ram 9* projects at each end,
and the steam is cushioned in the recess in the cover surrounding the
said rams; or in some cases instead of the rams an external air cylinder
is applied, and in other cases no provision for cushioning is necessary.
The travel of the valve may be regulated by throttling the supple-
mentary passages .g¹, g³, and g³. A convenient method of doing this is
by inserting set screws into them, which may be adjusted. Provision is
made for working the valve by hand when required.
The combination forming the improved arrangement of compound
pumping engine is shewn in Figs. 4, 5, and 6. The low-pressure
cylinder a and the high-pressure cylinder a³ are placed end to end with
the cover a, in which is a stuffing box between them. Both pistons b, b³,
are on the piston rod c, and the steam moved slide valve ƒ controls the
flow of steam to and from both cylinders. The valve fis in this instance
provided with the passages f¹ and f², as before described, and with the
passage f*, which is in communication with the recess or port ³ in the
casing 9; which is also provided with the passages g' and g³. The
recess g³ is connected with the exhaust from the high to the low pressure
cylinders by the passage f³. The passages h, h¹, for conveying the
steam from the cylinder a³ to the cylinder a are clearly shewn in the
Drawings.
In a compound pumping engine instead of using the compound valve
shewn in Figs. 4, 5, and 6, the simple valve shewn in Figs. 1, 2, and 3,
may be placed on the high-pressure cylinder, and be made to move an
ordinary slide valve on the low-pressure cylinder by means of a valve
spindle. The two ends of the cylindrical valve and the auxiliary
passages may be cast in one piece, and the slide valve may be cast in
another piece, and be merely pushed backwards and forwards by the