Improvements in Locomotive Engines.
Year: 1889

page_text: Date of Application, 11th Jan., 1889
Complete Specification Left, 1st Aug., 1889-Accepted, 7th Sept.,
1889
PROVISIONAL SPECIFICATION.
Improvements in Locomotive Engines.
We, WALTER MACKERSIE SMITH and JOHN WILLIAM SMITH both of 10 Otterburn
Terrace, Jesmond, Newcastle on Tyne, in the County of Northumberland, Engineers,
do hereby declare the nature of this invention to be as follows:-
In the Specification of a former application by one of us, John William Smith,
No. 5557, dated 14th April 1888, there is described means for admitting, in an
automatic manner, to the steam chest or cylinder of a locomotive which is running
with the steam shut off, air heated by being passed through a heated conduit or
conduits, the object being to prevent the pressure in the steam chest or in the
cylinder from falling appreciably below the atmospheric pressure.
Now according to our present invention we attain this same object by the admission
of steam alone or of steam mixed with air. When we employ steam alone we cause
it to be admitted in limited quantities when the main supply of steam is shut off at the
regulator. To this end we employ a piston, or its equivalent, subject on one side to
the atmospheric pressure and on the other side to the pressure in the steam chest or
cylinder. This piston is arranged to operate a valve, it may be a clack valve or a
piston valve, which affords connection between the steam chest or cylinder and the
boiler. When the atmospheric pressure is greater than the pressure in the steam
chest or cylinder the piston is moved in one direction and opens this valve to admit
the steam.
As soon as the pressure in the steam chest or cylinder becomes greater than the
atmospheric pressure the piston is moved in the opposite direction and the inlet of
steam is cut off.
When we employ steam mixed with air we substitute for the piston referred to
above, an air valve, the arrangement being such that when the pressure in the steam
chest or cylinder becomes less than that of the atmosphere this valve opens and admits
air, at the same time operating the steam valve, and admitting steam, as already set
forth.
It will be evident that apparatus according to this invention may be constructed in
various forms.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Locomotive Engines.
We, WALTER MACKERSIE SMITH and JOHN WILLIAM SMITH both of 10 Otterburn
Terrace, Jesmond, Newcastle-on-Tyne, in the County of Northumberland, Engineers,
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 has for its object improvements in locomotive engines. Balanced
valves have been used for distributing steam in most classes of engines. In marine
and other engines they always work under, pressure of steam, whereas locomotive
engines when descending inclines have their momentum kept up by the action of
gravity, and continue to move after steam has been shut off. Assuming balanced
valves, including piston valves, to be employed instead of the ordinary slide valves,
the action of these valves may be compared to what would occur assuming an ordinary

page_text: slide valves to be used that could not rise or lift off the face. Hence, by the action of
the engine piston, steam would be exhausted from the steam pipe and steam-chest and
the valve not being able to lift, no air could pass from the atmosphere into the steam
chest, except the small quantity that would pass in at the end of each stroke, and
which would be quickly drawn out again by the receding piston. In consequence the
engine would be unnecessarily retarded; air passing down the exhaust pipe would
press on the piston in the opposite direction to that in which it might be moving, and
this pressure not being nearly counter-balanced by that due to the rarified air
pressing on the opposite side of the piston, there would result undue tension of the
piston rod and connections during the backward stroke and undue compression during
the forward stroke.
In the Specification of Letters Patent granted to one of us namely John William
Smith, No. 5557, dated 14th April 1888, there are described means for obviating the
foregoing disadvantages by admitting in an automatic manner to the steam chest or
cylinder of a locomotive which is running with the steam shut off, air heated by being
passed through a heated conduit or conduits so that the pressure in the steam chest
or in the cylinder is prevented from falling appreciably below the atmospheric
pressure.
Now according to our present invention we attain the same result when employing
balanced valves by the use of steam alone, or of steam mixed with air.
To this end, the steam or the mixture of steam and air is admitted automatically to
the steam chest and thence to the cylinder by a suitable valve or valves opened, or caused
to open, by the pressure of the atmosphere when the pressure within the steam chest or
cylinder falls below that of the atmosphere; the steam, or steam and air, so admitted,
acts as would steam admitted in the usual way from the boiler, and thus serves to
prevent rarefaction in the steam chest and cylinder, so that at least a pressure
equivalent or approximately so to that of the atmosphere is exerted on both side of
the piston until the distributing valve cuts off communication with that part of the
cylinder behind the receding piston, when the enclosed steam, or steam and air, will
expand, decreasing in pressure. Towards the end of the stroke, the space in the
cylinder on the opposite side of the piston, by the same means, has its communication
cut off from the exhaust, the steam, or mixed steam and air being then compressed
and forming a cushion which arrests the movement of the piston, thereby obviating
undue strain such as hereinabove referred to.
A similar result might be obtained by admitting steam, or steam and air, direct to
the cylinder without passing through the steam chest, when the pressure of the
fluid exerted on the back of the receding piston would vary little throughout the
stroke.
When we employ steam alone we cause it to be admitted in limited quantities when
the main supply of steam is shut off at the regulator. To this end we employ a
piston, or its equivalent, subject on one side to the atmospheric pressure and on the
other side to the pressure in the steam chest or cylinder. This piston is arranged to
operate a valve, it may be a clack valve or a piston valve, which controls the con-
nection between the steam chest or cylinder and the boiler. When the atmospheric
pressure is greater than the pressure in the steam chest or cylinder the piston is
moved in one direction and opens this valve to admit the steam. As soon as the
pressure in the steam chest or cylinder becomes greater than the atmospheric pressure
the piston is moved in the opposite direction and the inlet of steam is cut off. In
some cases oil may be admitted as well as steam.
Referring to the annexed illustrative drawings,
Fig. 1 shews partly in section and partly in, elevation so much of a locomotive
engine as is necessary to illustrate the application thereto of apparatus according to
this invention for automatically admitting steam alone to the steam chests of the
cylinders.
Fig. 2 is a transverse section to a smaller scale in which the part to the left of the
vertical centre line A-B is taken on the line C-D of Fig. 1, and the part to the
right of the line A-B is taken on the line E-F of Fig. 1.

page_text: Fig. 3 shews in longitudinal vertical section, to an enlarged scale, one of the
apparatus detached, the steam valve and part of the air actuated piston being shewn
in elevation.
Fig. 4 is an end elevation of the apparatus.
Fig. 5 is a transverse section on the line O-P Fig. 4.
1,1 are the working cylinders of the engine, 2, 2 are the steam chests, 3, 3 are
liners in the steam chests; it is in these liners that the piston valves 3" work in the
example shewn. 4, 4 are live steam spaces. 5, (Fig. 1) is an exhaust steam space.
6, 6° are steam ports in the liner. 7, 7 are cylinder ports. 8, 8 are exhaust ports in
the liner.
To each steam chest 2 is fitted as shewn in Fig. 1, an apparatus of the kind shown
in Figs. 3, 4 & 5. This apparatus comprises a piston 9 arranged to slide in a
casing 10 the interior of which communicates by a branch pipe 11 with the steam
space in the steam chest 2. The piston 9 is subjected on its outer side (i.e. the
surface that faces to the left in Fig. 3) to the pressure of the atmosphere and on its
inner side (ie. the surface that faces to the right in Fig. 3) is subjected to the same
pressure that exists for the time being in the space 4 of the steam chest. The
piston 9 is formed with a shoulder at 12 that serves to limit its outward movement;
it is also formed or provided with a spindle or stem 13 that slides in a tubular
guide 14 which also serves to limit the inward movement of the piston. 15 is a
removable bush that admits of the piston 9 being easily removed or replaced. 16 is
a steam pipe in communication at one end with the boiler and 17 is a steam valve for
controlling the flow of steam through the pipe 16 to the casing 10 and thence to the
space 4 in the steam chest. The steam valve 17 has a seat at 18 and is provided with
a stem 19. The arrangement is such that when the atmospheric pressure is greater
than the pressure in the steam chest, the piston 9 will move inward and its stem 13,
acting against the stem 19 of the steam valve 17, will force this steam valve from its
seat and admit steam from the pipe 16 to the space 4 in the steam chest. When the
pressure in the space 4 in the steam chest becomes greater than the atmospheric
pressure, the piston 9 will move in the opposite direction, releasing the steam
valve 17 which will then be forced upon its seat and will cut off the supply of
steam.
From the foregoing description it will be understood that although the main supply
of steam may be cut off at the regulator, the steam pressure in the space 4 of the steam
chest can never be reduced below that of the external atmosphere for the time being.
At each stroke of the working piston of the engine, steam will be drawn past the
valve 17, the steam space 4, and one of the ports 7 until the cut-off takes place. This
steam will then be expanded through the remainder of the stroke until the exhaust
port opens, whereupon there will be a slight inrush of air from the exhaust pipe 5º.
On the return stroke of the working piston of the engine the steam from the engine
cylinder will be expelled through the port 7 the exhaust space 5 and the exhaust
pipe 5 until the port 7 is again closed, whereupon the remaining steam will be com-
pressed and this compressed steam will act as a cushion to the working piston of the
engine until the port 7 is again opened to the steam space 4. The steam so admitted
will act as a lubricant to the internal working parts.
When steam and air (with or without lubricant) are to be admitted, a convenient
arrangement is to provide in a chamber that communicates with the steam chest, or
cylinder, an air valve arranged to close against a suitable seat, and having its outer
side exposed to the pressure of the atmosphere, this valve being connected to a piston
valve or plunger that works in a chamber or cylinder from which there is a port com-
municating by a suitable pipe with the boiler or by suitable pipes with the boiler and
a lubricator or reservoir of lubricant. The arrangement is such that when the
pressure within the steam chest or cylinder falls below that of the external
atmosphere the air valve will automatically open and admit air at the same time
operating the steam valve and admitting steain, with or without lubricant as the
case may be.
Fig. 6 shews in section an arrangement of apparatus for admitting steam and air to

page_text: the steam chest or cylinder of a locomotive. 20 is the air valve mounted upon the
spindle 19 of the steam valve 17 which is arranged to work in a guide chamber 21
the outer end of the spindle being guided in a bearing 22. The air valve 20 is, like
the piston 9, Figs. 3, 4 & 5, subjected on its outer or left hand side to the pressure
of the atmosphere entering through openings 23 and on its inner or right hand side
is subjected to the pressure that exists for the time being in the steam chest. The
outlet orifice 16" of the steam pipe 16 is situated in the guide chamber 21 so that
when the pressure in the steam chest or cylinder falls below that of the atmosphere
and the air valve automatically moves from its seat and admits air, the steam valve
will be also operated, uncovering the orifice and admitting steam which together with
the air enters the steam chest or cylinder through the branch 11 as before.
Fig. 7 is a similar view to Fig. 6 shewing a modified arrangement for admitting
air and steam. In this case the spindle 19" of the air valve works in the guide
chamber 21 in which there is also located the stem 19 of the steam valve 17 which
closes the end of the steam pipe 16. This pipe is connected to the steam boiler as
before. The adjacent ends of the stem 19 and spindle 19" may advantageously be
about one sixteenth of an inch apart so that the steam and air valves may each rest
independently on its seat. When the air valve 20 is automatically opened its spindle
comes in contact with the stem of the steam valve 17 and opens that valve allowing
steam to flow out of that pipe as before.
In each case the apparatus automatically comes into operation after the main supply
of steam has been cut off at the regulator, and continues in operation until the engine
comes to rest, effectually preventing the pressure in the steani chest or cylinder or in
each, if applied to more than one, falling appreciably below that of the external
atmosphere. When the engine comes to rest the air actuated plunger and steam
valve or the air and steam valves, as the case may be, will be automatically operated
in the reverse direction by the pressure within the steam chest or cylinder and the
automatic admission of steam or steam and air will thus be arrested.
Our invention will enable a balance valve to be used for the distribution of steam to
the cylinders of a locomotive without unnecessary strain being put on the piston rod
and other parts of the engine.
Apparatus according to this invention may be used in connection with valves other
than balanced valves, for instance, with valves placed on the tops of cylinders and
which do not fall from the faces.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. For the purpose of destroying the vacuum and providing a cushion or cushions
between the working piston or pistons and the cylinder covers in a locomotive engine
and thereby preventing undue strain on the piston rod or rods and the connections
thereof when the pressure in the working cylinder or cylinders falls below that of the
external atmosphere and the engine is propelled by gravity or by its own momentum,
providing for the admission in an automatic manner of steam alone or of steam and
air to the working cylinder or cylinders of the engine, either direct or through-the
steam chest or chests, the arrangement being such that when the locomotive comes to
rest the automatic admission of steam or of steam and air will be arrested.
2. Apparatus substantially as hereinabove described with reference to and illustrated
in Figs. 3, 4 & 5 of the drawings annexed for admitting steam alone to a locomotive
engine cylinder either through the steam chest or direct for the purpose specified.
3. Apparatus substantially as hereinabove described with reference to and illustrated
in Fig. 6 of the drawings annexed (or modified as in Fig. 7) for admitting steam and
air to a locomotive engine cylinder either through the steam chest or direct.