Improvements in Slide Valves for Steam Engines.
Year: 1890

page_text: Date of Application, 27th May, 1890
Complete Specification Left, 27th Feb., 1891-Accepted, 18th Apr., 1891
PROVISIONAL
SPECIFICATION.
Improvements in Slide Valves for Steam Engines.
I, THOMAS TOWNSON, of 230, Vale Terrace, Etruria, Stoke-on-Trent, in the
County of Stafford, Engineer, do hereby declare the nature of this invention to be
as follows:-
The main object of my invention is to so construct and arrange the valve or
valves admitting and discharging steam from a steam engine cylinder, together
with the steam chest or chests containing such valve or valves, that the smallest
possible clearance is obtained, and the steam and discharge port or ports are
very short.
In steam engines with ordinary valve arrangements, it is usual to admit steam
through the side of the cylinder, by ports cast therein, and by so doing, considerable
losses are caused by large clearances.
To avoid this loss, in carrying out my invention I construct the cylinder covers
to contain the valves, and entirely dispense with side ports. By so doing the steam
and exhaust ports are very short and direct.
One method of constructing the cylinder cover consists in forming it like a valve
chest or box, and adapting a slide valve to work across its face at right angles
to the axis of the cylinder. The cylinder cover is furnished with a valve cover,
to allow the working faces to be planed and scraped, and to permit the slide to
be placed in position.
The valve stem is carried through the side of the cover, being suitably packed
by a stuffing box; and it is actuated by eccentric, on a shaft driven from the
main shaft, which secondary shaft is driven by bevel or other suitable gearing.
An expansion slide may be placed on the back of the main slide and actuated by
a second eccentric or in any other well known manner.
I may so construct my slide valve, that the steam admission and exhaust is
conducted by means of one passage in the cylinder cover; but I prefer to make
the steam and exhaust ports separate, in order to avoid the cooling action of the
exhaust steam.
My slide valve is constructed of such dimensions, that separate steam supply
and exhaust ports are controlled by it, and in one construction I allow the
lower edge of the slide to be widened out to a face upon which it slides to and
fro, so that it is upheld in position upon the corresponding cylinder cover face;
that is, the cylinder cover steam chest has two faces, one at or near right angles
to the other, and the valve edge rides upon one, while the steam pressure keeps
it up to the other face. I form the inlet port in the upper part, and the exhaust
port in the lower part of the valve, and allow the steam to be discharged through
the lower edge of the exhaust port into an exhaust cavity in the cylinder cover.
The steam pressure is admitted to one part of the cylinder cover, and the exhaust
is conducted away from anther part of it. I thus gain the advantages of short
ports, of small clearance, and minimum resistance, both for inlet and exhaust, and
steam jacketted cylinder cover as well.
The ports used by me pass through the cylinder cover, in a direction parallel to
the axis of the cylinder, and so, are only of length determined by the thickness
of the metal necessary for strength of the cover.
At the stuffing box end of the cylinder I construct my slide valve forked, so as
to pass the exterior of the stuffing gland, the upper part is used for steam admission
port, the lower for exhaust port.
D
لبيت
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CLERK & MARKS,
13, Temple Street, Birmingham, Agents for Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Slide Valves for Steam Engines.
I, THOMAS TOWNSON, of 230, Vale Terrace, Etruria, Stoke-on-Trent, in the
County of Stafford, 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 :-
The main object of my invention is to so construct and arrange, the valve or
valves admitting and discharging steam from a steam engine cylinder together
with the steam chest or chests containing such valve or valves that the smallest
possible clearance is obtained, and the steam and discharge ports are very short.
In steam engines with ordinary valve arrangements it is usual to admit steam
through the side of the cylinder by ports cast therein, and by so doing, considerable
losses are caused by large clearances. To avoid this loss, in carrying out my
invention, I construct the cylinder covers to contain the valves and entirely dispense
with side ports. By so doing the steam and exhaust ports are very short and
direct.
One method of constructing the cylinder cover consists in forming it like a valve
chest or box and adapting a slide valve to work across its face at right angles to
the axis of the cylinder. The cylinder cover is furnished with a valve cover to
allow the working faces to be planed and scraped and to permit the slide to be
placed in position. The valve stem is carried through the side of the cover being
suitably packed by a stuffing box and it is actuated by eccentric, on a shaft driven
from the main shaft, which secondary shaft is driven by bevil or other suitable
gearing.
An expansion slide may be placed upon the back of the main slide and actuated
by a second eccentric or in any other well known manner.
I may so construct my slide valve that the steam admission and exhaust is conducted
by means of one passage in the cylinder cover but I prefer to make the steam and
exhaust ports separate in order to avoid the cooling action of the exhaust steam.
My slide valve is constructed of such dimensions that separate steam supply and
exhaust ports are controlled by it; and in one construction I allow the lower edge
of the slide to be widened out to a face upon which it slides to and fro, so that it is
upheld in position upon the corresponding cylinder cover face; that is the cylinder
cover steam chest has two faces, one at or near right angles to the other, and the
valve edge rides upon one face while the steam pressure keeps it up to the other
face. I form the inlet port in the upper part and the exhaust port in the lower
part of the valve and allow the steam to be discharged through the lower edge of
the exhaust port into an exhaust cavity in the cylinder cover. The steam pressure
is admitted to one part of the cylinder cover and the exhaust is conducted away
from another part of it. I thus gain the advantages of short ports, of small
clearance and minimum resistance, both for inlet and exhaust. I also obtain a
steam jacketed cylinder cover. The ports used by me pass through the cylinder
cover in a direction parallel to the axis of the cylinder, and so are only of length
determined by the thickness of the metal necessary for the strength of the cover.
At the stuffing box end of the cylinder I construct my slide valve forked so as to
pass the exterior of the stuffing gland, the upper part is used for steam admission
port and the lower part for the exhaust port.
Referring to the accompanying sheet of drawings,
Figure is a section through the cylinder of an engine to which my invention
has been applied.
Figure 2 is a sectional end clevation of the valve as applied to the front, or piston
rod end of the cylinder, while
Figure 3 is a similar end elevation of a form of valve suitable where no piston
rod passes through the cover.
The slide valve E Figures 1 and is divided into two parts by the piston rod

page_text: boss, but is preferably cast in one piece and constructed in forked fashion as shown
in Figure 2. It is actuated from a second motion shaft K by an eccentric
suitably connected to the valve spindle O. The upper part carries the steam
port H, while the lower part carries the steam port G which connects as shown
in the case of the back cover in section, at the back end of the cylinder, between the
exhaust port G¹ in the cylinder cover C and the exhaust cavity G through the
working face L. When the valve F is in the position shown in section at the back
end of the cylinder the exhaust port G2 is open, and the steam port H2 is closed.
When the valve E is in position as shown in the front end of the cylinder the
steam port His open and the exhaust port G is closed. By this construction
of slide valve the only clearance spaces in the cylinder A due to the ports leading
from and to the slide valve are the very short ports H¹ and G in the cylinder
cover B, and H2 and G in the cover C, and the length of the ports depends
solely on the thickness of the covers B and C. These covers form steam chests
as well as cylinder covers and live steam is admitted by any convenient manner as
by the passages M and N. Suitable steam chest covers or auxiliary cylinder
covers C, D, are applied in order to allow of access to the valves, and in one
arrangement the cover C carries the stuffing gland through which the piston rod
passes as seen in Figure 1, but many known methods of construction may be
adopted to allow of easy access to the valves and their faces. The working face L
is at or
near right angles to the main valve face, but the valve easily keeps
both faces steam tight as the steam pressure in the valve chest forces it to the
main face as well as to the exhaust face. The end elevation shown in Figure 2
is partly in section to clearly indicate the position and shape of my valve. The
spindle O is attached to the valve in any usual manner and is placed slightly out
of centre with the valve, when it is desired to use a cut off plate as well as the
main slide.
The cut off plate is placed on the upper part of the valve above the port H
and is actuated by the spindle O¹ and an eccentric. The cut off plate is not shown
upon the drawings as it is well and commonly understood. The lower edge E' of
the valve E serves to cover the exhausting port G' when steam is being admitted
at the upper port H but the part E' may also be cut to form a steam port and
steam supplied through G' as well as through H'. Likewise an extra exhaust
port may be applied at the upper half if desired, but in this case the lower and
upper halves will be connected in such manner that they can be forced apart by the
steam pressure so as to bear properly on their opposing seats.
Figure 3 shows a sectional end elevation of the valve in the end cover
through which the piston rod does not pass and it requires no further explanation.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that
what I claim is :-
:-
(1) Arranging steam engine slide valves to work on faces in the cylinder
covers so that the steam and exhaust ports are very short, substantially as and
for the purposes hereinbefore described and illustrated in the accompanying
drawings.
(2) A slide valve working in a cylinder cover across a face at or near right
angles to the axis of the cylinder and having a second face at or near right angles
to the first face, a port in one face communicating with the cylinder through the
cover, and a port in the other face with the exhaust pipe, substantially as described
and illustrated.
(3) The arrangement of steam cylinder, cylinder covers, and slide valves herein-
before described and illustrated in the accompanying drawings.
Dated this 26th day of February 1891.
CLERK & MARKS,
13, Temple Street, Birmingham, Agents for Applicant.