Balanced Slide-valves for Steam and other Engines.
Year: 1890

page_text: Date of Application, 16th Jan., 1890
Complete Specification Left, 16th Oct., 1890-Accepted, 22nd Nov., 1890
PROVISIONAL SPECIFICATION.
Balanced Slide-valves for Steam and other Engines.
HORACE MUNCASTER, St. Georges Wellington Salop Mechanical Engineer do
hereby declare the nature of this invention to be as follows:-
This invention relates to an improved form of slide valve for the distribution of
steam or other fluid pressure, and is intended to be applied chiefly to engines
working under heavy pressures, and its object is to provide an improved method of
relieving the friction due to the pressure acting on the back of valve.
The valve is not essentially different from the ordinary slide valve in the manner
of distributing the steam or other fluid and may be single or double ported as most
convenient.
The improvement comprises a piece firmly bolted or otherwise fixed to the cylinder
port face, of such shape as to form a table with a flat surface at some distance from
the said port face, and at the same time not to interfere with the free passage of the
exhaust.
The slide valve is made to enclose the table piece and has a second face arranged to
make a steam-tight joint on the surface of table at the same moment as the valve face
is in contact with the cylinder port face, and from the back of valve is removed a
portion equal in area to correspond with the pressure of which it is required to relieve
the valve.
If desired the second or back face of valve may be formed by fixing a plate to back
of valve in which plate is an opening of the required size.
Dated this 14th dov of Jonna 1800
"COMPLETE SPECIFICATION.
Balanced Slide-valves for Steam and other Engines.
HORACE MUNCASTER St. Georges W. Wellington Salop Mechanical 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 relates to an improved form of slide-valve applied to engine cylinders
for the purpose of distributing steam or other fluid pressure.
The object of the invention is chiefly to provide an improved method of relieving
the pressure acting on the back of the valve and thereby lessening the friction on
the valve face due to such pressure.
This valve is not essentially different from the ordinary slide valve in the manner
of distributing the steam (or other pressure) or exhausting the same and may be
single or double ported as most convenient.
The invention may be described by the aid of the accompanying drawings:-
Fig. 1. is a sectional elevation of a double ported valve arranged according to this
invention shewing also part of the cylinder to which it is fitted also rod operating the
valve.
Fig. 2. is an elevation of valve and part of cylinder.
Fig. 3. is an elevation of cylinder port face with valve removed.
Fig. 4. is a transverse section of valve and part of cylinder.
Referring to Fig. 1 c is intended to represent part of steam engine cylinder of
which S, S, are steam-ports and e exhaust port and k chest filled with steam
pressure.

page_text: form a table with a perfectly flat surface d at some distance from and parallel to the
said face and is of such a shape as not to arrest the flow of the exhaust steam through
the exhaust port e.
The slide valve vis arranged to work over the table piece a and has a plane surface
at g in contact with the cylinder port face f and of the proper shape to give the
required distribution of the steam.
To the back of the valve vis fixed a plate p baving an opening o, o, o, o, of an area
corresponding with the amount of pressure of which it is found desirable to relieve
the valve, the said plate has a narrow strip forming a margin to the opening 0, 0, 0, 0.
This strip provides a surface h in a plane parallel to the valve face g and at a distance
from it equal to the depth of the table piece a so that when the valve is in working
condition the faces ƒ and g are in contact at the same moment as are the faces d
and h.
r is the rod communicating the motion to the valve.
The drawings shew the valve at one end of its travel giving steam to top steam-
ports and exhausting from the lower ones.
Having now particularly described and ascertained the nature of iny said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
(1) The employment of a plate p fixed to the back of the valve having an
opening 0, 0, 0, 0, for the purpose of relieving (or balancing) the pressure on the
valve.
(2) The forming of a narrow marginal facing h to the said opening.
(3) The employment of a table a having a plane surface d in contact with the
valve surface h for the purpose of preventing the pressure fluid from passing into the
exhaust port e through the opening 0, 0, 0, 0.
Dated this 14th day of October 1890.