IMPROVEMENTS IN STEAM ENGINES AND IN SLIDE VALVES FOR THE SAME
Year: 1871

page_text: LETTERS PATENT to Thomas Giles, of No. 11, Craven Street, Hulme,
Manchester, in the County of Lancashire, for the Invention of
"IMPROVEMENTS IN STEAM ENGINES AND IN SLIDE VALVES FOR THE SAME
"
"
IMPROVEMENTS IN STEAM ENGINES AND IN SLIDE VALVES FOR THE SAME
PROVISIONAL SPECIFICATION left by the said Thomas Giles at the
Office of the Commissioners of Patents, with his Petition, on the
14th August 1871.
I, THOMAS GILES, of No. 11, Craven Street, Hulme, Manchester, in
the County of Lancashire, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN STEAM ENGINES AND IN SLIDE VALVES FOR THE
SAME," to be as follows:-
This Invention has for its object improvements in steam engines. In
order to relieve the slide valve from the excessive pressure of the steam
upon it I form a plane surface on the back of the valve. A metal ring
rests on this surface and encloses the area from which the high-pressure
steam is to be excluded. This ring encircles a projection of cylindrical

page_text: or other form upon the cover of the steam chest, and by packing rings a
steam-tight joint is made between the two. By a small passage through
the back of the valve the space enclosed by the ring is always in connec-
tion with the steam outlet. The edge of the ring, which bears against
the back of the slide valve, is kept in close contact with it by the steam
pressure on the other edge. When two slide valves work back to back
in the same steam chest, the projection to carry the ring, in place of
being formed on the cover of the steam chest, is formed on the back of
one of the valves, the other valve having as before the plane surface to
slide in contact with the ring, or, as is preferable, both the valves have
plane surfaces upon them, and between them are two rings corre-
sponding with the ring and projection already referred to and sliding the
one on the other. The steam pressure acting on the edges of the rings
keeps them in steam-tight contact with the plane surfaces. A fixed
buckle or strap encircling the rings keeps the rings in their places.
The valves of marine engines, which are usually double ported, I make
with similar ports on the two sides. The back of the valve works on a
plane surface with grooves in it corresponding with the ports in the
valve face. The steam pressure keeps the plate in contact with the
back of the valve, but the whole back surface of the plate is not
exposed to this pressure, the steam being excluded from the greater part
of the back surface of the plate by a projection on the cover of the steam
chest and a steam-tight ring encircling it as already described. Screw
studs may also be used to adjust and support the plane surface plate.
In these arrangements, where the valve is kept up to its working face
only by steam pressure, it is free to leave it when the steam is cut off.
In the steam chest, or in the cylinder, or in the exhaust passage I
insert a clack valve in a suitable casing, with one end open to the steam
from the boiler and the other end open to the atmosphere. The steam
on entering this casing holds the valve tight by pressing on it, and when
steam is shut off the atmospheric pressure opens it by reason of the
greater external over the internal pressure, thereby allowing air to enter
behind the piston and fill the cylinder, and the slide valve shutting it to
the exhaust. The air in the cylinder is compressed before the advancing
piston, and acting through the piston and connecting rods is applied
direct to the crank axle of the engine to destroy the stored-up energy in
the moving train.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Giles in the Great Seal Patent Office on
the 14th February 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
GILES, of No. 11, Craven Street, Hulme, Manchester, in the County of
Lancashire, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of August, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Thomas Giles, Her special license that I,
the said Thomas Giles, my executors, administrators, and assigns, or such
others as I, the said Thomas Giles, 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 STEAM ENGINES AND IN SLIDE VALVES FOR THE
SAME," upon the condition (amongst others) that I, the said Thomas
Giles, my executors or administrators, 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 Thomas Giles, 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 thereof, that is to say :-
In the construction of the slide valves of steam engines I arrange
opposite to the valve face, parallel to it, a plane surface plate having
grooves in it corresponding with the ports in the valve face. The slide
working over the ports is thus exposed to similar conditions on its
opposite sides. The slide is caused constantly to bear upon the valve
face and the plane surface plate with a uniform pressure by the steam
acting on the back of the plane surface plate. The steam is in part

page_text: excluded from the back of the plane surface plate, so that the slide
may not be exposed to more than a proper working pressure.
Of the annexed Drawings, Figure 1 is a section of a pair of slide
valves as applied to an inside cylinder engine. a and a* are the valve
faces upon the cylinders with the usual ports in them; b and 6* are ·
plane surface plates with grooves corresponding with the ports; c and c*
are the slides connected with eccentrics in the ordinary way. The steam
pressure is excluded from a portion of the back surface of each of the
plates b and 6* by rings b¹ and 6¹× formed upon them. These rings fit
the one into the other, they are packed steam tight as is shewn, and by
holes in the plates 6 and 6× the enclosed space is put in communication
with the interior of the slides c and c*, which are always over the exhaust
ports of the cylinders. c¹ and c¹* are holes in the slides to provide free
passage between the steam ports of the cylinders and the grooves in
the plane surface plates. d is a holder fixed to the end of the steam
chest to prevent the plane surface plates travelling with the slides.
Figure 2 is a plan of the holder d and plate 6*.
A similar arrangement is applicable to a single cylinder engine. The
cover of the steam chest being provided with a ring which takes the
place of the ring b¹×.
A similar arrangement is also applicable where a separate cut-off slide
is employed. Such an arrangement is shown in section at Figure 3.
a is the valve face, 6 the plane surface plate, and c the main slide as
before; e is a cut-off slide working on the back of the main slide and
actuated usually by a separate eccentric; fis the cover of the steam chest,
it has a ring upon it to receive the corresponding ring 6 of the plate b.
Figure 4 is a plan of the main slide c, and Figure 5 is a plan of the cut-
off slide e.
In constructing locomotive steam engines I apply a valve or valves
to admit air to the cylinder when the steam is cut off whilst the engine
still runs forward. The air thus admitted is forced up the blast pipe and
effectually prevents a downward current through the blast pipe carrying
grit into the cylinder. If the reversing lever be put into mid gear the
air is compressed, and its resistance tends to arrest the forward motion
of the engine.
The valve may be placed on the exhaust passage, and then when the
engine is reversed it admits air to the cylinder in place of allowing the

page_text: cylinder to be supplied through the blast pipe. I combine a lubri-
cator with the valve, so that oil may be carried into the cylinder with the
air. The arrangement is shewn at section at Figure 6. a is the valve
closing with its own weight (which is small) upon a valve seat within a
casing or shell b, which by the flange b' is bolted upon the steam chest,
or in other convenient position to admit air to the cylinder. The valve
opens to admit air whenever the steam being cut off the pressure in the
cylinder becomes less than atmospheric; c is a vessel containing oil, it
has the small valve c¹ in its bottom, which is held to its seat by a light
spring. d is a tube provided with a wick to supply oil into the steam
chest and cylinder when the steam is on. When the steam is cut off
the valve a closes the bottom of the tube d, and the vacuum acts to suck
the lubricant down past the valve c¹.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I
claim,―
First. The improvements in slide valves substantially as described.
Second. The improvements in locomotive steam engines by the
application of air inlet valves substantially as described.
In witness whereof, I, the said Thomas Giles, have hercunto set
my hand and seal, this Thirteenth day of February, in the year
of our Lord One thousand eight hundred and seventy-two.
THOMAS GILES. (L.S.)