IMPROVEMENTS IN THE SLIDE VALVES OF S ENES
Year: 1867

page_text: LETTERS PATENT to Justin Thèvenet, of Mont-sur-Marchienne lez
Charleroy, in the Kingdom of Belgium, Civil Engineer, for the Inven-
TIDE VARING OF STEAM ENGINES"
COMPLETE SPECIFICATION filed by the said Justin Thèvenet at the Office
of the Commissioners of Patents, with his Petition and Declaration,
on the 13th March 1867, pursuant to the 9th Section of the Patent Law
Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JUSTIN
THEVENET, of Mont-sur-Marchienne lez Charleroy, in the Kingdom of
Belgium, Civil Engineer, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN THE
SLIDE VALVES OF STEAM ENGINES," and have petitioned Her Majesty to grant
unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that I verily believe
myself to be the first and true Inventor thereof.
NOW KNOW YE, that I, the said Justin Thèvenet, do hereby declare that
the following Complete Specification, under my hand and seal, fully describes
and ascertains the nature of my said Invention, and the manner in which the
same is to be performed, reference being had to the Drawing hereto annexed

page_text: and forming part of this Specification, and to the figures and letters marked
thereon.
This Invention consists in an improved construction of slide valve. The
improved slide valve is constructed of two parts forming the slide valve
proper.
These two parts A and B, Figure 1 (which is a section through the slide
valve), fit exactly one in the other, in such a way however as to admit of their
sliding one over the other. Each of these pieces is provided externally with
a metallic hoop D and E, which do the work of piston hoops. The frame C
is hollowed out exactly so as to receive the two parts A and B of the slide
valve, and the two metallic hoops acting as piston hoops in its interior
interrupt communication between the inlet and the outlet steam ports. The
perfect joint obtained by the employment of metallic hoops enables me to
obtain a friction slide valve under a given pressure between two friction plates,
one, X, being the friction plate with inlet and outlet steam ports, the other, Y,
being a plate which has to remain fixed at a distance regulated according to
circumstances, but in all cases fixed so as to be perfectly parallel to the first
plate. The valve being set up as herein-before described, if it were cylindrical
in its whole height it would evidently not have its two friction faces in perfect
contact with the friction plates Y, X, but to obtain this perfect contact it is
merely necessary to cause these friction faces to project out to such a super-
ficial extent that the pressure exerted on one and the other of the parts A
and B shall be sufficient to secure this perfect contact.
Figure 2 is a plan of Figure 1, and the plate Y is represented in red lines
to shew the slide valve. In certain cases (see Figure 3) it may be advan-
tageous to have the outlet port made in the plate Y, opposite the plate X, in
which the inlet ports would be made, the immediate effect of such an arrange-
ment being to remove a part of the resistance produced by the counter
pressure of the steam circulating in the escape pipes.
In the arrangement shewn in Figure 3 the plate Y forms one side of the
steam chest. The slide valve is not shewn in Figure 3, being similar to that
shewn in Figure 1. In case two slide valves work in the same steam chest,
as shewn in Figure 4, only one friction plate Y need be employed, which is
isolated in the steam chest so that each of its faces may act as a friction plate
opposite to the friction plate provided with outlet and inlet steam ports for
supplying each slide valve.
In the arrangement shewn in Figure 4 the plate Y may be cast with the
steam chest or merely fixed thereto. The two slide valves are not shewn in
Figure 4, being similar to that shown in Figure 1.

page_text: Figure 5 shews an arrangement for the introduction of the steam into the
interior of the slide valve, and in this case the escape takes place outside this
valve, the metallic hoops E and D acting in its interior. The metallic hoops
in this case are retained by an additional sheath F fitting externally at its
middle in a hollow part or space made in the two parts A and B of the slide
valve proper. The exterior part of this slide valve, as herein-before described,
only being in contact with the escape steam, the frame may be of any desired
form, provided the setting up of the faces with the two parts A and B of the
slide valve be perpendicular to the friction surfaces. Internal projections on
the friction surfaces from A to B in the interior of the valve will insure the
perfect contact of these surfaces. In the arrangement shewn in Figure 5 the
plate Y forms a side of the steam chest.
Having now described the nature of my Invention, and the manner of
carrying the same into effect, what I claim is, the peculiar construction of
slide valve as herein-before described and represented in the accompanying
Drawing.
In witness whereof, I, the said Justin Thèvenet, have hereto set my
hand and seal, this Twelfth day of March, in the year of our Lord
One thousand eight hundred and sixty-seven.
J. THEVENET. (L.S.)