IMPROVEMENTS IN SLIDE VALVES AND COCKS."
Year: 1877

page_text: LETTERS PATENT to Stewart Robertson, of 8, Union Court, Old Broad Street,
in the City of London, for the Invention of "IMPROVEMENTS IN SLIDE VALVES
AND COCKS."
PROVISIONAL SPECIFICATION left by the said Stewart Robertson at the
Office of the Commissioners of Patents on the 17th November 1877.
STEWART ROBERTSON, of 8, Union Court, Old Broad Street, in the City of
London. "IMPROVEMENTS IN SLIDE VALVES AND COCKS."
This Invention has for its object improvements in slide valves and cocks. I con-
struct slide valves of wedge-like or prismatic form, and cause them to travel in the
direction of the length of the prism between faces in which ports are formed; these
faces are inclined to each other at an angle corresponding to that of the prism.
Where the valve is intended for use as a sluice valve or cock I form a single port
in each face, and there is no port in the valve. The valve then can be placed either
so as to cover the ports or so as to allow the free flow of the fluid between them.
When the valve covers the ports it is pressed firmly against the faces by an
incline.
The valve may be actuated by means of a screw, or rack teeth may be formed
upon the valve to engage with a pinion upon an axis set at right angles to the base
of the prism.
When the valve is employed as the distributing valve of a motive-power engine
it may have a port or ports formed in it, and other ports may be formed in the faces.
The valve in this case may be pressed towards the spaces either by a spring or by
the pressure of the fluid acting against the base.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Stewart Robertson in the Great Seal Patent Office on the 17th May
1878.
STEWART ROBERTSON, of 8, Union Court, Old Broad Street, in the City of
London. " IMPROVEMENTS IN SLIDE VALVES AND COCKS."
This Invention has for its object improvements in slide valves and cocks. I con-
struct slide valves of wedge-like or prismatic form, and cause them to travel in the
direction of the length of the prism between faces in which ports are formed; these
faces are inclined to each other at an angle corresponding to that of the prism.
Where the valve is intended for use as a sluice valve or cock I form a single port
in each face, and there is no port in the valve. The valve then can be placed
either so as to cover the ports or so as to allow the free flow of the fluid between
them. When the valve covers the ports it is pressed firmly against the faces by
an incline.
The valve may be actuated by means of a screw, or rack teeth may be formed
upon the valve to engage with a pinion upon an axis set at right angles to the base
of the prism.
When the valve is employed as the distributing valve of a motive-power engine
it may have a port or ports formed in it, and other ports may be formed in the
faces. The valve in this case may be pressed towards the faces either by a spring
or by the pressure of the fluid acting against the base.
. In order that my said Invention may be most fully understood and readily
carried into effect, I will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a transverse section, and Figure 2 is a longitudinal section of a sluice
valve or cock constructed according to my Invention.
a, a, is the sliding valve of wedge-like or prismatic form; it works between two
faces b, b, in each of which there is a port marked b¹. The faces b, b, are formed
within a casing which is closed at the ends by covers c and c'. In the cover c
there is a stuffing box, through which the spindle & passes; and this spindle within
the stuffing box has right and left handed screw threads formed upon it, one of
which works in a corresponding thread cut in the cover c, and the other in a screw
nut let into the valve a. It is obvious that by turning the spindle d the valve is
moved endwise, and so the ports b₁ can be covered or uncovered at pleasure. e is
an incline formed within the valve casing; the valve itself has a similar incline
upon it, and when the valve is forced home these inclines cause the valve to be
pressed firmly up to the faces b, b, and so the valve is caused to make a fluid-tight
joint against each face. It is not essential that the valve should close fluid-tight
against both of the faces b, but it is necessary that on both sides of the valve there
should be true surfaces along which it may slide to its place. The right and left
handed screw is a convenient instrument for moving the valve to and fro, but other
well-known mechanical contrivances may be resorted to for this purpose.
Figure 3 is a transverse section, and Figure 4 is a longitudinal section of another
sluice valve or cock similar to that already described, but varied in detail as
respects the forms of the parts.
Figure 5 is a transverse section, and Figure 6 is a longitudinal section of a
wedge-like or prismatic valve working between ports in faces on either side of it,
such valve being here applied as the distributing valve of a motive-power engine.
fis a cylinder, in which steam or other fluid acts upon a piston; f¹, fi, are passages
leading to the ends of the cylinder, and they terminate in ports in one of the
faces g, against which the prism-shape valve h works. In the opposite face i there
is another port, serving as the outlet; and there is in this case a port or passage

page_text: through the valve itself, and the steam or fluid in passing out of the cylinder
traverses the valve from side to side. The valve may receive motion from an
eccentric in the usual manner. In this arrangement the pressure of the steam or
fluid suffices to hold the valves in contact with the faces. In some cases I provide
adjustable guide rails to hold the valves to their seats; this would be necessary, for
example, if, in an arrangement similar to that shewn, the supply of steam or other
fluid to the cylinder were through the port or passage in the valve, with the outlet
from the cylinder into the casing around the valve.
Figure 7 is a transverse section, shewing the application of the Invention to the
valves of a compound engine, where the steam or fluid is first worked in a small
cylinder and is then expanded into a second and larger cylinder. k and are the
two cylinders, and the passages leading to and from these cylinders terminate in
two inclined faces m, m, within a casing; n and o are the valves, the one capable
of sliding upon the back of the other, but together they form a prism occupying the
space between the two inclined faces, which space in the previous arrangements was
occupied by the single valve. The valve n controls the flow of the steam or fluid
from the boiler which enters by the centre port in the valve face into the small
cylinder K, and from this cylinder to the chamber or receiver p, whence the
valve o controls its passage into and from the larger cylinder 1. The valves n
and o may be operated by eccentrics in the usual manner. There are perforations
in the back of the valve o to permit the escape of any steam or fluid which may
find its way between the valves. In this arrangement the pressure of the fluid
serves to hold the valves against the faces, and so compensates for wear by pressing
the valves towards the narrower part of the casing; or adjustable guide rails and
set screws may be provided.
Figure 8 shews a modification of the arrangement shewn in Figure 7, in which
the backs of the valves are inclined, and the compensation for wear is obtained by
the sliding of one valve upon the other in a transverse direction.
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 construction of slide valves, sluice valves, or cocks, with a sliding valve
of wedge-like or prismatic form sliding in the direction of its length between ports
or passages in two corresponding faces, substantially as described.
Second. The construction of slide valves adapted to be used as distributing
valves of motive-power engines with a sliding valve of wedge-like or prismatic
form, having a port or passage through it, such valve sliding in the direction of its
length between two corresponding faces provided with ports or passages, sub-
stantially as described.
Third. The arrangements in which prism-shaped slide valves are adapted to be
used as the distributing valves of compound engines, substantially as described.
In witness whereof, I, the said Stewart Robertson, have hereunto set my
hand and seal, this Fifteenth day of May, in the year of our Lord One
thousand eight hundred and seventy-eight.
CART & DO DOPERTSON