IMPROVED EXPANSION VALVES FOR STEAM ENGINES
Year: 1855

page_text: LETTERS PATENT to Joseph Malcomson, of Portlaw, in the County of
Waterford, in Ireland, Merchant, and Robert Shaw, of the same Place,
Merchant, and William Horn, of. Mark Lane, in the City of London,
Engineer, for the Invention of "IMPROVED EXPANSION VALVES FOR STEAM
ENGINES."
Sealed the 10th August 1855, and dated the 12th March 1855.
PROVISIONAL SPECIFICATION left by the said Joseph Malcomson, Robert
'Shaw, and William Horn at the Office of the Commissioners of Patents,
with their Petition, on the 12th March 1855.
We, JOSEPH, MALCOMSON, ROBERT SHAW, and WILLIAM HORN, do hereby
declare the nature of the said Invention for "IMPROVED EXPANSION VALVES FOR
STEAM ENGINES" to be as follows:-
We propose in any description of slide valve 'that may be used, and on that
portion of the valve which opens to admit the steam into the cylinder, to place
louvres or grids, so that the steam before entering the cylinder shall pass
through the openings in the same. These openings. are covered by sliding
grids or covers, which slide across the valve, and are opened and shut at the
proper times by levers or other mechanical means connected with the moving
power, or by means of studs or rollers fixed on the sliding covers, and which
are brought by the reciprocating motion of the slide valve into contact with

page_text: inclined abutments in the valve case, or vice versa. The studs, or rollers, or
abutments may be permanently fixed in their places, or may be capable of
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Malcomson, Robert Shaw, and William Horn in the
Great Seal Patent Office on the 11th September 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOSEPH
MALCOMSON, of Portlaw, in the County of Waterford, in Ireland, Merchant,
and ROBERT SHAW, of the same Place, Merchant, and WILLIAM HORN, of
Mark Lanc, in the City of London, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Ler Letters
Patent, bearing date the Twelfth day of March, in the year of our Lord One
thousand eight hundred and fifty-five, in the eighteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto us, the said
Joseph Malcomson, Robert Shaw, and William Horn, Her special licence,
that we, the said Joseph Malcomson, Robert Shaw, and William Horn, our
executors, administrators, and assigns, or such others as we, the said Joseph
Malcomson, Robert Shaw, and William Horn, our 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 "IMPROVED EXPANSION VALVES FOR STEAM ENGINES," upon the condition
(amongst others) that we, the said Joseph Malcomson, Robert Shaw, and
William Horn, our executors or administrators, by an instrument in writing
under our hands and seals, or under the hand and seal of one of us, 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 William Horn, on behalf of myself and
the said Joseph Malcomson and Robert Shaw, 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, reference being had to the accompanying Drawings, and to the figures
and letters marked thereon, that is to say:-

page_text: The Invention relates to the constructing expansion valves for steam engines
by the combination of a slide valve with a grid valve or valves mounted upon
it, as herein-after described.
Figure 1, Sheet I. of the accompanying. Drawings, is a view of the back of
one of our improved expansion valves; Figure 2 is a view of one half of the
face of the same; Figure 3 is a longitudinal section of the valve, and the seat
or face on which it works; Figure 4 is a transverse section of the valve, one
half of it being taken through the centre of the slide valve A, and the other
half through the transverse grid valve H at one end of the slide valve A.
Figure 5 is a transverse section, shewing a portion of the other grid valve G,
at the opposite end of the slide valve. The same letters refer to similar parts
in each Figure. A is the slide valve which works against the face B, in which
are the two passages C and D leading to the top and bottom of the cylinder.
E, E, is a ring fitted into a recess in the back of the slide valve A, and pressed.
by springs or packing against the planed surface of the back of the valve box.
A pipe from the back of the valve box communicates with the condenser in
the case of a condensing engine, or with the atmosphere in the case of a
non-condensing engine. The passages a, b, in the slide valve thus form the
eduction passages for the escape of the steam from either end of the cylinder.
The steam passages d and e are made in the form of a grid or series of narrow
parallel passages at each end of the slide valve. The slide valve is moved by
a rod F, which passes through a stuffing box in the valve box, and is connected
to an excentric in the ordinary manner, and the action of the valve is so far
similar to that of an ordinary slide valve. Over the grids d and e are two
long narrow grids G and II, which work in slides in a direction transverse to
that in which the slide valve A moves. When the openings in these grids G
and H correspond with those in the grids d and e, the steam has a free passage.
through them, but when the grids G and I are shifted so as to bring their
bars opposite to the openings in the grids d and e, the passage for the steam
is closed. Figures 4 and 5 shew these two positions of the grids. The motion
is communicated to the grids in any convenient manner. Thus, a pin or stud
may be fixed to each grid, and these pins may come in contact with inclined
pieces of metal fixed in the valve box, so that the motion of the slide valve
A may effect the transverse motion of the grids. Another method of working
the grid valves is shewn in the Drawing. I is a light shaft or rod, turning
in bearings on the back of the slide valve A, and passing through a stuffing
box in the end of the valve box. This rod I travels backwards and forwards
with the slide valve, and it carries two little levers or fingers, J and K,,
which enter cavities in the grids G and H respectively, so that by slightly

page_text: turning the rod I, the grids G and H may be shifted, and opened or closed.
The grid valves are arranged so that when one is fully open, the other
is closed. When they are placed in an intermediate position, both valves
are partly open, and are then properly placed for starting or handing the
engine.
Figure 6, Sheet II, is a plan, and Figure 7 is a section, shéwing one
method of giving the required motion to the rod I. Eis a shaft driven by
wheel work at the same speed as the main or crank shaft of the engine. The
slide valve is driven by an excentric on the shaft L, or on the main shaft in
the ordinary manner. The rod I is supported by a bearing M, in which it is
capable of turning, and also of sliding backwards and forwards with the motion
of the slide valve. N and O are two small levers fixed on the rod I, and sup-
porting a short rod P, which slides' backwards and' forwards through a fork Q,
which is attached to a frame R, sliding between guides S, S. The frame R
carries two small rollers, r, which bear against a cam T on the shaft. L. By
this means, at each revolution of the shaft L, the frame R is moved up and
down in the guides S, and the rod I thus receives a slight angular motion on
its axis, first in one direction and then in the other. The cam T is so placed
on the shaft I that these motions take place when the piston of the engine is
in the positions at which it is desired to cut off the steam. Thus we will
suppose the slide valve A in Figure 3, Sheet I., to be inoving in the direction.
of the arrow, and about to admit the steam to the port or passage D. The
grid H is open, so that as soon as the apertures or passages e in the slide valve
come opposite to the passage D, the steam passes into the cylinder, and the
piston commences its stroke. When the piston reaches the point at which it
is desired to shut off the steam, the grid valve H is closed by its cam, and the
grid valve G is opened. The steam is thus cut off, and the piston completes
its stroke. "The opening of the grid valve G does not admit the steam to the
passage C, until the return of the slide valve brings the apertures or grid d
opposite to the passage C: The piston then makes the return stroke, and the
steam is cut off by the closing of the grid valve G, while at the same time the
grid valve H is opened, so as to be ready to admit the steam to the passage. D
on the return of the slide valve A. The cam T is capable of sliding endways
on the shaft L, but is nevertheless compelled to revolve with it by means of a
groove and feather..
One end of the cam is made of the form shewn in Figure 7, and the other
end t is cylindrical. The intermediate part is sloped or shaped so as to gradu-
ally unite the two parts. By shifting the cam along the shaft, the cylindrical
part t may be brought between the rollers r, r, and the frame R will thus be

page_text: kept stationary in an intermediate position. The grid valves G and Hare
thus kept stationary in the middle of their course, and they are thus both
partly open. The slide valve A then acts like an ordinary slide valve, and the
engine may be reversed or handed in the ordinary manner by means of any of
the usual apparatus for that purpose. The cam T is shifted backwards and
forwards on the shaft L by means of a forked lever entering a groove or collar
on the cam. The cam may also be so formed as to cut off the steam at different
times, according to the position of the cam on the shaft, and the degree of
expansion may thus be varied without stopping the engine. As the motion
of the grid valves G and H is simultaneous, they might be made of one piece
of metal, so as to form (so to speak) a single valve, but we prefer to make
them separate as being more convenient. The form of the slide valve may
be varied, and the eduction passage may be made in the face against which
the valve works, instead of in the back or cover of the valve box.
Having now described the nature of the said Invention, and in what manner
the same is to be performed, we wish it to be understood that we do not claim
generally the placing of expansion slide valves on the backs of ordinary slide
valves; nor do we claim generally the constructing slide valves in the form of
grids; but what we claim is, the constructing expansion valves for steam
engines by the combination of a slide valve with a grid valve or valves
mounted upon it, and working in a direction transverse to the direction of
the motion of the slide valve, as herein-before described.
In witness whereof, I, the said William Horn, have hereunto set my
hand and seal, this Eleventh day of September, in the year of our
Lord One thousand eight hundred and fifty-five.
WILLIAM HORN. (L.S.).