IMPROVEMENTS IN AND IN CON- NECTION WITH SLIDE AND OTHER VALVES
Year: 1859

page_text: LETTERS PATENT to Bryan Donkin, of Berdmondsey, in the County of
Surrey, Engineer, for the Invention of "IMPROVEMENTS IN AND IN CON-
NECTION WITH SLIDE AND OTHER VALVES."-A communication from abroad
by Thomas Coates, of Sommerfeld, Silesia, Engineer.
Sealed the 31st January 1860, and dated the 2nd August 1859.
PROVISIONAL SPECIFICATION left by the said Bryan Donkin at the
Office of the Commissioners of Patents, with his Petition, on the
2nd August 1859.
I, BRYAN DONKIN, of Bermondsey, in the County of Surrey, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
AND IN CONNECTION WITH SLIDE AND OTHER VALVES," (conimunicated to me from
abroad by Thomas Coates, of Sommerfeld, Silesia, Engineer), to be as
follows:-
This Invention has for its object the obtainment of a more gradual admission
and exit of steam or other fluid through the ports of a steam or other engine,
and this I obtain, firstly, by forming the passages through the valve each of a
narrowed or tapered form, or of such other form, that when the passage into or
from the port is at first opened the steam shall not pass through the whole
breadth of the port, but through a small portion of the same only, that portion
gradually increasing as the valve advances or recedes. Instead of the passage
through the valve being shaped as before described, the cylinder ports
themselves may in some cases be so shaped for the same purpose, or both

page_text: valve passages and the ports may be so shaped; and, secondly, I place slides
worked by a right and left handed screw-threaded spindle upon the back of
the valve, and form the passage through the back of the valve in the same
manner and for the same purpose as already described in reference to the
passages in the front or face of the valve. By means of this arrangement I
am enabled to regulate the admission of steam in such manner as to adjust it
to the varying velocities of the piston, and also I am enabled to cut the steam
off at different parts of the stroke whilst the engine is in motion.
The improvements are applicable in whole or in part to steam engines,
water engines, meters, and all other like machines.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Bryan Donkin in the Great Seal Patent Office on the
2nd February 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BRYAN
DONKIN, of Bermondsey, in the County of Surrey, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of August, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Byan Donkin, Her special licence that I, the said Bryan Donkin,
my executors, administrators, and assigns, or such others as I, the said
Bryan Donkin, 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, 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
AND IN CONNECTION WITH SLIDE AND OTHER VALVES," (communicated to me from
abroad by Thomas Coates, of Sommerfeld, Silesia, Engineer,) upon the
condition (amongst others) that I, the said Bryan Donkin, my executors or
administrators, by an instrument in writing under my, or their, or one of their
hands and scals, 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 Bryan Donkin, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-

page_text: formed, to be particularly described and ascertained in and by the following
statement thereof, reference being had to the Drawings hereunto annexed,
that is to say :-
This Invention has for its object the obtainment of a more gradual admission
and exit of steam or other fluid through the ports of a steam or other engine,
and this I obtain, firstly, by forming the passages through the valve each of a
narrowed or tapered form, as shewn in the accompanying Drawings and herein-
after referred to, in order that when the passage into or from the port is at
first opened the steam shall not pass through the whole breadth of the port,
but tl.rough a small portion of the same only, that portion gradually increasing
as the valve advances or recedes. Instead of the passage through the valve
being shaped as before described, the cylinder ports themselves may in some cases
be so shaped for the same purpose, or both valve passages and the ports may
be so shaped; and, secondly, I place slides worked by a right and left handed
screw threaded spindle upon the back of the valve, and form the passage
through the back of the valve in the same manner and for the same purpose as
already described in reference to the passages in the front or face of the valve.
By means of this arrangement I am enabled to regulate the admission of
steam in such manner as to adjust it to the varying velocities of the piston, and
also I am enabled to cut the steam off at different parts of the stroke
whilst the engine is in motion.
•
The improvements are applicable in whole or in part to steam engines,
water engines, meters, and all other like machines.
I proceed to show the manner in which these improvements are carried into
effect.
Figure 1 is a section of that part of an ordinary steam engine known as the
"steam and exhaust passages," with a slide A constructed according to this
Invention applied thereto; Figure 2 is a face view of the slide, showing the
shape of the edge; it is so shaped in order to let the steam pass the steam
ports in a regular proportion to the speed of the piston at the first part of
its stroke; Figure 3 is a section shewing one of these slides made to cut off
at rds of the stroke; Figure 4 is a face view of the slide shewing the shape of
the edge which lets in and shuts off the steam as before, and also a similar
shape for letting off or exhausting the steam in the same gradual manner;
Figure 5 shows a modification in the shape, and the dotted lines on the same
Figure a further modification in the shape of the edge of the slide.
The manner in which the second part of this Invention is performed is
shewn at Figures 6 and 7. Figure 6 is a section of the steam and exhaust
passages of an ordinary steam engine, with the expansion slides adapted

page_text: thereto; Figure 7 is a face view of the slide, with the shape of the edges of
the slide itself, and also the edges where the expansion slides work, the
expansion slides themselves being supposed removed.
A is a slide similar to those herein-before described, but with pieces B, B,
cast on the ends so as to form a face for the expansion slide C', C", to
work on.
These expansion slides are sent further apart or drawn nearer
together by a screw, on which is cut a right-handed thread D and a left-
handed thread E; the end of the screw is carried through a stuffing box in
the slide jacket, as is usually the case, and is worked in any usual well-known
manner. The end of the screwed rod outside the slide jacket may be so
connected with the driving apparatus by any mechanical means that the screw
can be turned by a handle, whereby the two expansion slides C', C",
be drawn nearer together or moved further apart. By this means the
expansion can be varied at pleasure, as, if the two slides C', C, are set
farther apart than shewn, they will cut the steam off sooner than stroke of
the piston; and if set nearer together than shewn, they will cut off the steam
later than stroke.
may
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I declare that I claim as the improve-
ments in and in connection with slide and other valves,―
First, making the edges of the slides in the particular manner shewn in the
accompanying Drawings, in order that they shall admit the steam gradually
in proportion to the speed with which the piston is travelling during the first
portion of its stroke.
Second, making the edges of the exhaust part of the slide, as shewn in the
accompanying Drawings.
Third, I claim the method of setting the expansion slides shewn in Figure 6,
and the employment thereof in combination with slides with edges formed in
manner and for the purposes herein-before described and illustrated in the
accompanying Drawings.
In witness whereof, I, the said Bryan Donkin, have hereunto set my
hand and seal, this First day of February, One thousand eight hundred
and sixty.