Improvements in or relating to Balanced Slide Valves for Steam Engines.
Year: 1888

page_text: Date of Application, 16th Oct., 1888
Complete Specification Left, 16th July, 1889-Accepted, 12th Oct., 1889
Improvements in or relating to Balanced Slide Valves for Steam
Engines.
A communication from abroad by GUISEPPE ZARA and ENRICO RIVA, of Florenco, in
the Kingdom of Italy.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.L.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, in the County of Lancaster, and 323, High
Holborn, in the County of Middlesex, Civil Engineer, do hereby declare the nature of
this invention to be as follows :-
The invention has for its object a balanced slide valve for steam engines of all kinds
(stationary, marine, locomotive, etcetera). By the invention only a suitable pressure
of the slide valve upon its seating is. permitted, whatever may be the pressure in the
steam chest.
In carrying out the invention the elasticity of a thin plate of metal, or a diaphragm
is used, so as to entirely do away with the use of packing, elastic joints, pistons, and
other arrangements hitherto made use of.
Upon a slide valve of suitable construction whose outer face is smooth, a metallic
plate is placed resting on ribs or their equivalent. Two projections which form part
of the steam chest cover, prevent the said plate from following the motion of the slide
valve. In the cover of the steam chest a circular or other opening is made, through
which the steam chest is placed in communication with a diaphragm, or with the
interior of a chamber having elastic walls, but of sufficient thickness to support the
pressure of the steam.
Owing to the elasticity of the walls, a cover which is placed on the outer face of
the chamber or diaphragm and attached by means of a connecting rod or stay to
the aforesaid metallic plate, would have a tendency to be forced upward by the pressure
of the steam. The pressure of the steam, however, acts in opposite directions, namely,
on tho metallic plate as well as on the said cover, and thus tends to prevent the
extension.
The stay or connecting bolt is bored throughout its whole length, or it may be a
tube or pipe which establishes communication between the space formed by the
air can
exterior shell of the slide valve and the metallic plate and the atmosphere;
also penetrate by the same means the space within the walls of the slide valve itself by
means of a hole. The two faces of the metallic plate will consequently be subjected to
two different pressures, that of the steam on the exterior surface and that of the
atmosphere on the interior face. Under these conditions the steam will exercise
pressure in two opposite directions, namely upon the diaphragu or cover of the elastic
chamber and upon the metallic plate, which two parts as aforesaid are connected by a
stay bolt.
The different parts of the apparatus can be made of such dimensions that they
will be capable of reducing the pressure of the steam on the slide valve to what-
ever pressure is thought suitable, and it thus forms a balanced slide valve.
In order to insure the plate resting upon the slide valve, before or after the steam
is introduced into the steam chest, the elasticity of the chamber or diaphragm can
be made use of, adjusting nuts being provided on the stay rod which regulate the
pressure.
The shape of the diaphragm or elastic chamber may be modified to suit require-
ments it may take a circular shape with flat faces, or may be a flat or almost flat
plate or diaphragm, or it may be bulged or rounded over the orifice. The cover is
changed in shape to suit the shape of the diaphragm, but the other parts are not
changed in their mode of working.

page_text: The stay rod may sometimes be jointed.
In special cases a spring may be applied to the cover in order to assist the
diaphragm in maintaining the nietallic plate on the surface of the slide valve.
Dated this 15th day of October 1888.
COMPLETE SPECIFICATION.
Improvements in or relating to Balanced Slide Valves for Steam
Engines.
A communication from abroad by GUISEPPE ZARA and ENRICO RIVA, of Florence, in
the Kingdom of Italy.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, and 323, High Holborn, in the County of Middlesex, Civil
Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
This invention has for its object a balanced slide valve for steam engines of all.
kinds (stationary, marine, locomotive, etcetera). By the invention only a suitable
pressure of the slide valve upon its seating is permitted, whatever may be the
pressure in the steam chest.
In carrying out the invention the elasticity of a thin plate of metal, or a diaphragm
is used, so as to entirely do away with the use of packing, elastic joints, pistons, and
other arrangements hitherto made use of.
Referring to the accompanying sheet of drawings and to the Figures and letters of
reference marked thereon:-
Figures 1 and 1 are sections at right angles to one another, of the improved
slide valve, while
Figure 1 is a plan thereof.
Figure 2 is a view of a modification of the improved slide valve.
Upon a slide valve A A of suitable construction whose outer face is smooth, a
metallic plate B B with edges CC is placed, resting on ribs or their equivalent.
Two projections D D, which form part of the steam chest cover, prevent the said
plate from following the motion of the slide valve. In the cover of the steam chest,
a circular or other opening E, Figure 1, is made, through which the steam chest is
placed in communication with a diaphragm or with the interior of a chamber G,
having elastic walls m, but of sufficient thickness to support the pressure of the
steam.
Owing to the elasticity of the walls, a cover N, which is placed on the outer face of
the chamber or diaphragm G and attached by means of a connecting rod or stay to
the aforesaid metallic plate, would have a tendency to be forced upward by the
pressure of the steam, as indicated by the arrow f, Figure 1. The pressure of the
steam, however, acts in opposite directions, namely, along f', on the metallic plate, as
well as on the said cover, and this tends to prevent this extension. The plate B B is
joined, by means of the stay or bolt t, to the wall N of the elastic chamber.
The two faces
The stay or connecting bolt t is bored throughout its whole length, or it may be a
tube or pipe q, which establishes communication between the space formed by the
exterior shell of the slide valve and the metallic plate (that is between the space CC)
and the atmosphere; air can also penetrate by the same means the space within the
plate B B and the walls of the slide valve itself, by means of a hole r.
of the metallic plate B B will, consequently, be subjected to two different pressures,
that of the steam on the exterior surface, and that of the atmosphere, on the interior
face. Under these conditions, the steam will exercise pressure in two opposite
directions, namely, (along f) upon the diaphragm or cover of the elastic chamber G,

page_text: and (along ¹) upon the metallic plate B B, which two parts, as aforesaid, are con-
nected by a stay bolt.
The different parts of the apparatus can be made of such dimensions that they will
be capable of reducing the pressure of the steam on the slide valve to whatever
pressure is thought suitable, and it thus forms a balanced slide valve.
In order to insure the plate B resting upon the slide valve, before or after the steam
is introduced into the steam chest, the elasticity of the shell m of the chamber or
diaphragm can be made use of. The latter can be forced from the position x to the
position y, by turning the nut S, screwed on to the lid N.
The shape of the diaphragm or elastic chamber may be modified to suit require-
ments it may take a circular shape, with flat faces, or inay be a flat or almost flat
plate or diaphragm, or it may be bulged or rounded over the orifice.
Figure 2 shows a modification where the diaphragm or elastic chamber G is con-
structed of two pieces of corrugated metal, one of the pieces being an extension of the
cover plate N.
The cover is changed in shape to suit the shape of the diaphragm, but the other
parts are not changed in their mode of working.
The stay rod may sometimes be jointed.
In special cases, a spring, may be applied to the cover N, in order to assist the
diaphragm in maintaining the metallic plate B B on the surface of the slide valve.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondents, I declare that what I claim is :-
1. The manufacture of balanced slide valves, for steam engines, in which an elastic
chamber or shell (substantially as described and shown) is made use of.
2. The general arrangement and construction of balanced slide valves, substantially
as described and shown."
T
11
T
T
WM. P. THOMPSON & Co.,
Agents for the Applicant.