IMPROVEMENTS IN STEAM ENGINES
Year: 1873

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN STEAM ENGINES."-A communication from
abroad by William Gordon Ulery, of New York, in the United
States of America.
COMPLETE SPECIFICATION filed by the said John Henry Johnson at
the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 3rd April 1873, pursuant to the 9th
Section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Mid-
dlesex, Gentleman, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN STEAM ENGINES," and have petitioned Her Majesty to grant unto me,
my executors, administrators, and assigns, Her Royal Letters Patent
for the same, and have made solemn Declaration that the said

page_text: Invention is communicated to me from abroad by William Gordon Ulery,
of New York, in the United States of America.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, 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 :—
This Invention is designed to relieve the vacuum in the steam cylinder
of an engine which is formed when after the steam is shut off the engine
continues in motion, as in the case of locomotive travelling on a de-
scending grade with steam shut off. In this case a vacuum is formed
behind the moving piston in the steam cylinder, which greatly retards the
motion and injures the machinery.
Two modes of accomplishing this result are here represented; the one
in Figures 1 and 2, the other in Figures 3 and 4. The improvements
are especially applicable to balanced slide valves, but can also be applied
and used with valves which are not positively held down upon their
heads.
The first part of this Invention consists in combination with the valve
and its enclosing case of one or more puppet or other valves, applied
either to the valve or to its case, and in constant communication with the
exhaust cavity of the valve, automatically operating to admit air from
the said exhaust cavity into the interior of the steam chest when steam
is shut off and the engine continues in motion, as herein-after described.
In the Drawing, Figure 1 is a transverse section through a valve chest
and valve, showing the application of these improvements; and
Figure 2 is a longitudinal sectional elevation of the same. Similar
letters of reference indicate corresponding parts.
As above stated, the puppet valves may be applied either to the valve
or to its inclosing case. In the arrangement shown in the Drawing the
puppets are represented as located in the valve case, and the exhaust
cavity of the valve is open at the top so as to communicate with the valve
openings in the case.
A is a slide valve working steam-tight under the case B, for the
of halanaince it the coid valvo carving sections of reaking

page_text: rings in the grooves O working against the under side of case B, to
which they are fitted steam-tight.
It is obvious that this valve or any valve balanced in a similar manner
cannot be raised off its seat as the ordinary slide valves can, by the
atmospheric pressure in the exhaust port or opening D, when steam
is shut off from the engine and the latter continues in motion, as in the
case of a locomotive going down an incline; consequently a vacuum
will be formed behind the piston, which will powerfully resist the motion
of the engine.
It is therefore proposed to provide for admitting the air to the steam
chest to enter the cylinder at the ports in the same manner that the
steam does to prevent the formation of the vacuum.
The plan which is here shown for accomplishing this is to arrange the
puppet valves E in suitable openings F through the case B leading from
the exhaust cavity D, which is cut through the top of the valve to the
steam space in the steam or valve chest, so that they will be kept closed
by steam pressure while steam is admitted to the chest, but will be
opened by the back pressure of the air through the exhaust as soon as
the steam is shut off.
The air so admitted to the steam chest will flow through the steam
ports G and follow up the piston, thereby preventing the forming of a
vacuum behind it.
This arrangement necessitates drawing the supply of air through the
exhaust, that is to say, it is taken in through the exhaust port under the
valve, and must pass through the latter before it can reach the steam
space of the chest.
The second mode of overcoming the difficulty specified which I shall
now proceed to describe differs from the one above stated in that the air
is admitted into the steam space of the chest, not from beneath the
valve and through the exhaust, but from above or outside of the valve
and the exhaust. This is productive of advantage under some circum-
stances, as for instance, when the exhaust pipe opens into the smoke
stack of the locomotive, in which case the air taken in through the
exhaust is apt to carry with it cinders and dirt, which will grind the
valve face and seat, and entering the cylinder will wear and injure the
piston. By providing for the automatic admission of air into the steam

page_text: chest from a point above or outside of the valve and exhaust no such
liability is incurred, and the air may enter free from dust and cinder.
line x,
In the accompanying Drawing Figure 3 is a top view of the valve
chest with the cover removed, and Figure 4 is a section of the same on
x, Figure 3. A is a slide valve working steam-tight under the
case B for the purpose of balancing it, the said valve carrying sections
of packings rings in grooves C working against the under side of case B
to which they are fitted steam-tight; D is the exhaust port, and G the
steam ports. To prevent the formation of a vacuum which will other-
wise take place when after steam is shut off the engine of which the
valve and chest may be supposed to form part continues in motion, I
provide as above set forth for the automatic admission of air at this time
into the steam space of the chest from the above or outside of the valve
and exhaust.
The accompanying Drawing in Figures 3 and 4 represents an arrange-
ment for this purpose which I shall now proceed to describe.
In one of the sides of the steam chest is located a puppet valve H
closing an opening or passage in the side of the chest, and arranged to
open internally or toward the inside of the chest. When steam is
let on the valve is kept closed by steam pressure; but when steam is shut
off and a vacuum is forced in the steam chest by reason of the
continuance of movement of the engine, the superior pressure of the
outside atmosphere presses open the valve, and air is thus admitted into
the steam chest, and will thence flow through the steam ports G and
follow up the piston in the steam cylinder, thereby preventing the for-
mation of a vacuum in rear of said piston.
The valve H may be otherwise arranged and located if preferred. It
can for instance be placed in the top of the steam chest.
A light spiral spring I may be employed to assist in closing the valve
and also to steady it, as will be readily understood without further
explanation.
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 con-
sider to be novel and original, and therefore claim as the Invention is,―
First. The combination of the slide valve and its inclosing case with
one or more puppet valves, arranged to have constant communication

page_text: with the exhaust cavity of the valve, substantially as described, and
operating automatically to admit air therefrom into the steam chest at
the time and in the manner set forth.
Secondly. In combination with the valve chest the air admission
valve, operating automatically at the time and in the manner set forth,
to admit air into said chest through a passage or opening leading from
the exterior atmosphere, and entering the valve chest at a point outside
of the steam valve and the exhaust, substantially as described.
In witness whereof, I, the said John Henry Johnson, have to this
my Complete Specification set my hand and seal, this Third day
of April, Ơne thousand eight hundred and seventy-three.
J. HENRY JOHNSON. (L.S.)