IMPROVEMENTS IN SLIDE VALVES FOR STEAM ENGINES
Year: 1859

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in
the County of Middlesex, and of 166, Buchanan Street, in the City of
Glasgow, North Britain, Gentleman, for the Invention of "IMPROVEMENTS
IN SLIDE VALVES FOR STEAM ENGINES." -A communication from abroad
by Richard C. Bristol. of Chicago. United States of America.
Sealed the 23rd December 1859, and dated the 26th July 1859.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 26th July 1859.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of 166, Buchanan Street, in the City of Glasgow, North
Britain, Gentleman, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN SLIDE VALVES FOR STEAM ENGINES," a communication from
abroad by Richard C. Bristol, of Chicago, United States of America, to be as
follows:-
This Invention relates to a peculiar construction and arrangement of slide
valve applicable to steam or gas engines, whereby the partial or entire
neutralizing of the pressure thereon is effected, whilst facility is at the same
time afforded for the combination with the slide of an expansion or "cut off"
valve.

page_text: These improvements consist in the application and use of four or more
partial rollers for supporting a portion of the slide, such partial rollers not
being subject to any friction upon their axes, nor involving any increase in the
length of the steam chest. A sufficient portion only of the periphery of these
partial rollers is circular to admit of the full traverse of the valve, the
remainder of the periphery being cut away so as to admit of their being
placed nearer together. These partial rollers are guided and kept in position
at or near their bearing points by suitable projecting grooved or channelled
lips, and by pins passed through suitably formed slots in the rolling surfaces,
or the grooves or channels may be dispensed with, and flat-headed screw pins
used for keeping the partial rollers in position. The means above described
for keeping the partial rollers in position may also be applied, if found
desirable, to complete circular rollers.
Another portion of this Invention consists in so arranging an expansion
valve on the back of the supported part of the slide above referred to, and
disposing suitable steam passages through both parts of the slide that the
steam is conveyed to the cylinder ports through such passages above with the
usual effect due to expansive working, whilst the two parts of the valve may be
allowed to work to a limited extent relatively to each other, without involving
a leakage of steam at the joints, which last object may in some cases be
effected by interposing suitable packing between the two parts of the valve.
In order to adjust the two parts of the valve, it is proposed to work the front
and back parts in free relations to each other for a time, and then to secure
the two parts rigidly together by set screws after the force piece of the valve has
become sufficiently grooved upon the cylinder's face to form в perfectly steam-
tight joint.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office on
the 26th January 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN J
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex, and
of 166, Buchanan Street, in the City of Glasgow, North Britain, Gentleman,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of July, in the year of our Lord s
One thousand eight hundred and fifty-nine, in the twenty-third year of

page_text: Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Henry Johnson, Her special license that I, the said
John Henry Johnson, my executors, administrators, and assigns, or such
others as I, the said John Henry Johnson, my executors, administrators, or
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 "IMPROVEMENTS IN SLIDE VALVES FOR STEAM ENGINES," a communication
from abroad by Richard C. Bristol, of Chicago, United States of America,
upon the condition (amongst others) that I, the said John Henry Johnson,
by an instrument in writing under my hand and seal, 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 John Henry Johnson, 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, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say.:-
The said Invention relates to a peculiar construction and arrangement of
slide valve applicable to steam or gas engines or apparatus whereby the
partial or entire neutralizing of the pressure on the slide is effected, whilst
facility is at the same time afforded for the combination with the slide of an
expansion or "cut-off" valve,
These improvements consist in the application and use of four or more
rolling surfaces or partial rollers for supporting a portion of the slide, such
partial rollers not being subject to any friction upon their axes, nor involving
any increase in the length of the steam chest. A sufficient portion only of the
periphery of these partial rollers is left to allow of the full traverse of the
valve, the remainder of the periphery being cut away so as to obtain greater
compactness, These partial rollers are guided and kept in position at or near
their bearing points by suitable projecting grooved or channelled lips and by
pins passed through suitably formed slots in the rolling surfaces, or the
grooves or channels may be dispensed with, and flat-headed screw pins used
for keeping the partial rollers in position. The means above described for
keeping the partial rollers in position may also be applied, if found desirable,
to complete circular rollers,

page_text: Another portion of this Invention consists in so arranging an expansion
valve on the back of the supported part of the slide above referred to, and
disposing suitable steam passages through both parts of the slide, that the
steam is conveyed to the cylinder ports through such passages alone with the
usual effect due to expansive working, whilst the two parts of the valve may
be allowed to work to a limited extent relatively to each other, without
involving a leakage of steam at the joints, which last object may in some
cases be effected by interposing suitable packing between the two parts of the
valve. In order to adjust the two parts of the valve, it is proposed to work
the front and back parts in free relations to each other for a time, and then
to secure the two parts rigidly together by set screws after the face piece of
the valve has become sufficiently grooved upon the cylinder face to form a
perfectly steam-tight joint.
And in order that the said Invention may be fully understood, I shall
now proceed more particularly to describe the same, and for that purpose
I shall refer to the several Figures on the Sheet of Drawings hereunto
annexed, the same letters of reference indicating corresponding parts through-
out all the Figures.
Figure 1 of the accompanying Drawings is a side elevation of a locomotive
slide valve constructed according to this Invention; Figure 2 is an end
elevation of the same; Figure 8 is a vertical section taken along the line 1, 2,
in Figure 2; Figure 4 is a vertical section taken along the line 3, 4, in
Figure 1 and Figure 5 shows a modification intended to allow of packing
being placed between the two parts of the valve.
It is well known that the pressure of steam upon a slide valve tends to
produce a great amount of friction, and various devices have been made
known with a view to diminish this injurious effect. One of these has been
to construct upon the back of the valve a short cylinder, with a piston working
therein, which being suspended by a link attached to the cover of an elevated
steam chest, relieves the valve from much of the pressure of the steam. S
Another way has been to mount the piston of such a valve upon wheels
running in ways parallel to the face of the valve. These and other previously
known devices have either been expensive in construction, or have but
imperfectly accomplished the object, while they have necessitated an unusually
capacious steam chest, thus rendering the expansion of the steam, when an S
independant expansion or "cut-off" valve is used, less effectual; and in no case,
when the pressure has been supported from off the valve, has the very common
and desirable plan been practicable of working a "cut-off" valve on the back
of the main slide valve.

page_text: The valve is constructed in two portions A, B, the latter being fitted
steam-tight into the former, so that it is adapted to slide vertically therein to
a certain extent, as represented, without allowing steain to pass through the
joint. Set screws C, C, are provided, by which the portions A, B, may be
made to hold their relative places very firmly if required. The "cut-off"
valve D is fitted to slide steam-tight on the upper face of B, and is guided
thereon by ledges or lips. The top of B overhangs A at each side, as repre-
sented by B, B, and the partial rollers E, E, which are introduced between
these overhanging portions and the cylinder face M, support B on the circular
portions of their several peripheries, and compel it to travel in a plane parallel
to the face M.
The form which I prefer for these rollers is shown in Figures 1 and 2.
The overhanging portions of B are made to enclose and confine the upper
sides or circular ends of these partial rollers, as shewn by B' and B', and the
lower sides or lower circular ends thereof are enclosed or confined by analagous
means M³ and M' on or near the cylinder face. I also make suitable aper-
tures E through the partial rollers E near their extremities, and insert
pins B', which extend through these slots into the metal of the back piece B
and similar pins M', which extend into the metal of the cylinder face M.
These apertures or slots are of such form as to allow the partial rollers to
play to the proper extent without touching the pins, so long as the partial
rollers are in their correct positions, but the moment one of the partial
rollers E becomes in any considerable degree displaced at either the top or
the bottom, it presses the sides of the corresponding slot against the pin, and
thus prevents itself from becoming more displaced. Any sensible displace-
ment of either of the partial rollers also causes it to meet the other, or to
meet the stops B' at each vibration, and thus to aid in preventing it from
becoming any further displaced. The red outlines show the condition of these
partial rollers at the end of each movement of the valve.
:
The steam is admitted to the ports in the cylinder through the passages a, a,
and b, b, in the respective parts A, B. These passages are arranged as
represented, so that the part A may slide vertically upon B, and vice versa,
without closing the passages a, b, and without producing any leak at the joint
or dividing line. In commencing to operate the valve, the set screws C, C,
are slackened, and the part A is thus allowed to be pressed down into steam-
tight contact with the cylinder face M by the pressure of the steam on that part
of A which is not protected therefrom by B. It is usually worked for several
days in this condition, so that it is free to rise and sink without affecting B,
and is then (either at a single operation, or by gradually increasing the

page_text: tightness at several operations,) set firmly in relation to B, by turning the set
screws C, C, in which case it continues to fit tightly upon the cylinder face M,
by reason that the motion of B is parallel thereto.
With the form and proportion shown in Figures 1, 2, 3, and 4, the part B
'is fitted in perfect steam-tight contact with the part A, yet not pressing against
the same so tightly as to prevent a motion of the parts, one within the other.
To avoid the necessity for such accurate workmanship, the form shown in
Figure 5 may be adopted, if preferred, and india-rubber or other suitable
packing may be inserted, as represented by G, G..
It will readily be seen that this Invention is capable of being constructed
in various forms and proportions other than those which I have here repre-
sented. For example, any variety of "cut off" or expansion valve or device
which is suitable to work on the back or within the body of other slide valves,
may be employed in lieu of the valve D. Broad heads may also be formed
on the pins B' and M', which pins may be threaded and tapped into the
respective parts so as to act as bolts, and thus a lateral play of the partial
rollers E may be prevented by the heads of the bolts in lieu of by the lips B
and M³, as represented, or the sides of the steam chest may, if desired, or
when it is necessary to economise space, be made to touch and confine E.
Instead of making the valve in two parts, as shown by A, B, it may be made
in one piece, and the ways B' be made adjustable by means of screws or
wedge-shaped keys or jibs, or other suitable means. Many other modifications
may readily be adopted, without varying substantially from the principal
features of my Invention.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe in conclusion that what I consider to be novel and
original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent, is,―
First, the general constructions and arrangements of slide valves for steam
engines, and their combination with expansion or "cut-off" valves, as herein-
before described.
Second, the system or mode of wholly or partially supporting the pressure
of the steam on a slide valve by means of rollers or partial rollers E, working
in ways B, as herein-before described.
Third, confining the upper and lower edges of the partial rollers E by means
of lips or projecting ribs, as herein-before described.
Fourth, the peculiar combination of parts of slide valves, whereby the parts
A and B are allowed to work to a limited extent relatively to each other,

page_text: without affecting the action of the steam, or allowing an escape of the same
through the joints, as herein-before described.
Fifth, the application and use of the set screws C, C, for the purpose of
adjusting and tightening or securing together the two parts A and B of the
valve, as herein-before described.
In witness whereof, I, the said John Henry Johnson, have hereunto set
my hand and seal, this Twenty-sixth day of January, One thousand
eight hundred and sixty.
J. HENRY JOHNSON. (L.S.)