Improvements in Compound Engines.
Year: 1890

page_text: Date of Application, 19th Déc., 1890
Complete Specification Left, 18th Sept., 1891-Accepted, 24th Oct., 1891
PROVISIONAL SPECIFICATION.
Improvements in Compound Engines.
I, WALTER MACKERSIE SMITH, of 10 Otterburn Terrace, Jesmond, Newcastle-
on-Tyne, in the County of Northumberland, Engineer, do hereby declare the nature
of this invention to be as follows:-
This invention has for object improvements in compound engines, and has
reference to means for enabling them to start easily and safely. It is more particu
larly applicable to locomotive engines, but may be applied to other descriptions of
engines.
According to this invention each end of the high pressure cylinder is con-
nected by a pipe or passage, controlled by a non-return valve, with the receiver
of a compound engine to which steam is admitted immediately the regulator or
stop valve is opened, through a valve which closes as soon as the pressure in
the receiver attains a certain determined amount. The arrangement is such
that should' the distributing valve of the high pressure cylinder cover both
stean ports of that cylinder at starting the high pressure piston will be subject
on both sides to the reduced pressure of the steam in the receiver and will
consequently be nearly in equilibrium, and tlie steam distributing valve of the
low pressure cylinder will then admit steani from the receiver to that cylinder
and cause the engine to move, but should the low pressure distributing valve
cover both steam ports at starting then the high pressure distributing valve will
admit high pressure steam to the high pressure cylinder thereby destroying the
equilibrium of the piston' therein' and causing the same to move, at the same
time causing the non-return valve at that end of the cylinder to cut off com-
munication with the receiver and the other end of the cylinder, but the high
pressure piston cannot be subjected to a greater pressure at starting than that
due to the difference between the boiler pressure and the receiver pressure, so
that the sudden and severe strain that would otherwise be thrown on the high
pressure piston and connected motion during the first part of the stroke, will be
counteracted or prevented. The first exhaust of steam from the high pressure
cylinder creates a pressure in the receiver sufficient to keep the admission valve
closed, and the engine commences to work compound. Should the pressure in
the receiver at any time during the working fall below normal amount the valve
for admitting boiler steam thereto will again open.
In the form of valve
apparatus which I prefer for this purpose the boiler pressure (or the boiler
pressure modified by the action of the regulator) acts upon one valve or piston
which I will call' the admission valve, and the pressure in the receiver acts on
another valve or piston which I will call the cut off valve. The two valves
are coupled or placed in working connection with each other it may be by a
perforated hollow stem or by other suitable means, and provision is made for
the escape of steam that may leak past the cut off valve. The areas of these
two valves are so proportioned that the admission valve closes at a given
difference of pressure between the steam in the steam pipe and that in the
receiver.
In some cases instead of the pressure in the receiver being maintained such that it
shall be at least a given proportion of the pressure in the steam pipe it is desirable
that it shall be inaintained constant through a considerable range of boiler pressure.
To this end the cut off valve is no longer arranged to be controlled by the pressure
in the receiver, but by pressure of steam admitted from the boiler past a loaded valve
(which I will call the controlling valve). This valve is by preference loaded with an

page_text: adjustable spring, and reduces the pressure of the steam which passes through
it by a definite amount. It is this pressure that acts on the cut off valve
against the pressure in the steam pipe on the admission valve. As the con-
trolling valve is subjected on one side to a constant load and allows steam to
pass it from the boiler until the pressure exerted on the cut off valve equals
the boiler pressure minus a pressure equivalent to the load placed on the valve
by the spring, it will be seen that the pressure exerted on the cut off valve
will increase or decrease as the boiler pressure increases or decreases. The
result is that the increased or decreased boiler pressure tending to lift the
admission valve and by its means the cut off valve, is balanced by the increased
or decreased pressure acting on the cut off valve and tending to close the
admission valve, so that a constant pressure is maintained on the back of the
admission valve, and the pressure in the receiver is maintained practically
constant.
By varying the load on the controlling valve the pressure in the receiver can
be increased when it is desired to increase the power of the engine.
By this arrangement a desired constant pressure can always be maintained on the
low pressure piston independently of the rise or fall of the boiler pressure so long as
the boiler pressure is above the pressure required in the receiver. By this means a
constant power will always be developed by the low pressure piston, and the steam
emitted from the exhaust pipe will be constant so that the action of the blast on the
fire will be maintained practically constant during the working of the engine.
Dated this 19th day of December 1890.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
CODE.LDIN SIECIFICATION.
Improvements in Compound Engines.
I, WALTER MACKERSIE SMITH, of 10 Otterburn Terrace, Jesmond, Newcastle
on Tyne, in the County of Northumberland, Engineer, do hereby declare the
nature of this invention and in what manner-the-same-is-to-be-performed-to-be-par-
ticularly described and ascertained in and by the following statement :-
This invention has for object improvements in compound engines, and--has
reference to means for enabling such engines to start easily and safely. It is more
particularly applicable to compound locomotive engines, but may be applied to
other descriptions of compound engines whether constructed with two or more
cylinders.
According to this invention each end of the high pressure cylinder is connected
by a pipe or passage, controlled by a non-return valve, with the receiver of the
compound engine to which steam is admitted immediately the engine regulator or
stop valve is opened, by a valve which closes as soon as the pressure in the receiver
attains a certain pre-determined amount. The arrangement is such that should
the distributing valve of the high pressure cylinder cover both-steam ports of that
cylinder at starting, the high pressure piston will be subject on both sides to the
reduced pressure of the steam in the receiver, and will consequently be nearly in
equilibrium and the steam distributing valve of the low pressure cylinder will then
admit steam from the receiver to that cylinder and cause the engine to move.
Should however the low pressure distributing valve cover both low pressure steam
ports at starting, then the high pressure distributing valve will admit high pressure
steam to one end of the high pressure cylinder thereby destroying the equilibrium
of the pressure on the opposite sides of the piston therein and causing the latter
to move, at the same time causing the non-return valve at that end of the cylinder
to close and cut off communication with the receiver. The other end of the cylinder

page_text: will however be in communication with the receiver and the high pressure piston
cannot therefore be subjected to a greater pressure at starting than that due to
the difference between the boiler pressure and the receiver pressure, so that the
sudden and severe strain that would otherwise be thrown on the high pressure
piston and the parts connected therewith during the first part of the stroke, will
be counteracted or prevented. The first exhaust of steam from the high pressure
cylinder creates a pressure in the receiver sufficient to keep the admission valve
closed, and the engine commences to work compound.
In the accompanying drawings,
Fig. 1 is a transverse vertical section through the smoke box, shewing the high
and low pressure cylinders and steam pipes, of a compound locomotive embodying
iny invention.
Fig. 2 is a longitudinal section thereof along the axis of the high pressure
cylinder; and
Fig. 3 is a horizontal section through the valve chests shewing the high and low
pressure distributing valves in such positions that steam will, be admitted to boch
high and low pressure cylinders at starting.
Fig. 4 is a longitudinal central section through .the valve chest and adjacent
parts of the high pressure cylinder; and
Fig. 5 is a similar view of the valve chest and adjacent parts of the low pressure
cylinder.
Fig. 6 is a vertical central section of one arrangement of valve according to this
invention for admitting high pressure steam to the receiver.
Fig 7 is a vertical central section and
Fig. 8 is a part vertical section of another arrangement of valves, the said
sections being taken in planes at right angles to one another.
Fig. 9 is a horizontal section on the line a Fig. 8.
Fig. 10 is a vertical central section shewing a further modification thereof.
Figs. 1, 2 and 3 are drawn to a smaller scale than the remaining figures.
Referring to Figs. I to 5 inclusive A is the shell of the smoke box; B the high
pressure cylinder; B₁ the low pressure cylinder; C the high pressure valve chest ;
C' the low pressure valve chest; D the main steam pipes and D'D' auxiliary
steam pipes which serve as hereinafter described to supply steam through an
admission or reducing valve situated at D³, to the receiver E of the engine. F is
the exhaust or blast pipe of the locomotive.
The valve chest C, shewn more clearly in Fig. 4 and in which is situated the
distributing valve G, is provided with a pair of non-return valves H, H' controlling
openings that are situated between the steam ports II' respectively of the high
pressure cylinder, and the receiver E of the engine. The valve chest C₁ of the
low pressure cylinder B¹ is provided with two distributing valves G¹ (Fig. 3)
controlling the low pressure steam ports 12 [³ and opening the same alternately to
the receiver E and to the exhaust F. The distributing valves G and G¹ are shewn
as of the piston valve type, but other forms of distributing valves can be used if
desired. Figs. 4 and 5 shew the relative positions of the distributing valves G, G¹
of the high and low pressure cylinders respectively, the piston of the high pressure
cylinder being shewn at or about three fourths of its stroke when moving to the
right and the low pressure piston being shewn at or near the left hand end of its
stroke when moving to the right, the cranks being set at right angles. The
relative direction of motion of the valves and pistons, and the direction of flow
of steam, are indicated by arrows. It will be seen that with the valve G in the
position shewn in Fig. 4, the high pressure steam space is shut off from both
ends of the high pressure cylinder B. In order to start the engine, steam is
admitted to the steam space J from the main steam pipe D, and to the receiver E
from the auxiliary steam pipes D1, D2, the pressure in the latter case being
diminished on passing the admission or reducing valve at D³. The set of steam
ports 1 (Fig. 4) being open to the receiver, steam from the said receiver will pass
direct to the corresponding side of the high pressure piston B2 the pressures on

page_text: the top and bottom of the valve Hbeing then equal. The communication between
the steam chest J and the set of steam ports I however being closed by the dis-
"tributing valve G, the pressure of steam on the underside of the non-return
valve Hwill be greater than that on its upper side, consequently the said valve
-will be raised and steam will pass through to the left hand side of the
-piston B thereby placing the pressure on the two silles-of-the said piston nearly
"in equilibrium.
In Fig. 5 the communication between the receiver E and the left hand set of
ports is shewn opened by the distributing valve G₁ so that steam will pass
from the receiver E to the left hand side of the low pressure piston and
cause the engine to move, the right hand set of ports I at this time being open to
the exhaust F.
Should both sets of ports of the low pressure-cylinder-be closed at starting, then
high pressure steam will be admitted to one end of the high pressure cylinder, 'say
for example tofthe end at which the valve H¹ is situated. This will immediately
close the said valve but the other side of the pistou being open to the receiver
through the distributing valve and the valve H, the high pressure piston will not
practically be subjected to a greater pressure than that due to the difference
between the boiler pressure and the receiver pressure.
The non-return valves H H are shewn as of the "mushroom" type, the con-
nection to the steam ports being by passages formed in the casting of the cylinders.
Various other forms of non-return valves, such as foot valves, may however 'be
used, singly or in duplicate and arranged side by side or one above another, and
the connections may be made by means of pipes communicating with the receiver
and 'the ends of the cylinder. It is preferable however that these valves should be
automatic in their action so as to open by the steam pressure in the receiver to
admit steam to both sides of the high pressure piston and to close by the increased
pressure of steam on the admission of high pressure steam to the cylinder by the
distributing valve-G. The position of the reversing-rod-in full-gear or otherwise
is immaterial to the action of these valves, there being no connection between
them..
Should the pressure-in-the-receiver during-the-working, fall below-the-normal
"degree which it is desired to maintain therein, high pressure steam will be auto-
matically admitted thereto, as hereinafter described, to restore the said pressure
through the auxiliary steam pipes D₁ D2 and the valve situated at D³. In one
arrangement of valves for this purpose, and which is shewn in Fig. 6, the boiler
pressure (or the boiler pressure modified by the action of the regulator) acts upon
a valve or piston Kwhich I will call the admission-valve,-and-the-pressure in the
receiver acts on another valve or piston K' which I will call the cut off valve. The
two valves are fitted in a suitable casing K and are coupled or placed in working.
connection with each other it may be by a hollow stem K³ provided with lateral
perforations K, or by other suitable means, provision being made, as for example
by a hole K, for the escape of steam that may leak past the cut off valve. The
boiler pressure in the pipe D' acting on the valve K₁ tends to raise the same, while
the pressure in the receiver through the pipe D2 acts on the valve K2 and on the upper
side of K the effect in each case being proportional to the pressure and to the area
on which the same acts. The areas of the valves are so proportioned that the
admission valve is closed-at a-given relative-difference of pressure between the steam
in the steam pipe and that in the receiver. When the pressure in the receiver falls
below its normal degree relatively to that of the boiler pressure, the steam pressure
in the pipe 'D' will raise the valve K' and high pressure steam will pass into the
pipe D thereby augmenting the pressure therein until the same is sufficient to again
close the valve K
In some cases, instead of the pressure in the receiver being maintained such that
it shall be a given proportion of the pressure in the steam pipe, it is desirable that
it should be maintained constant through a considerable range of boiler pressure.
To this end the arrangement of reducing valve shewn in Figs. 7, 8 and 9 may be

page_text: employed, in which the cut off valve K² is arranged to be controlled not by the
pressure in the receiver, but by pressure of steam admitted to a chamber L³
through the steam pipe D' and a pipe D' past a loaded valve L (hereinafter called
the controlling valve). This valve is by preference.loaded with an adjustable
spring L' and reduces the pressure of the steam which passes through it, by a
definite amount. It is this pressure that acts on the cut. off valve or piston K
against the pressure of the steam in the steam pipe on the admission valve K'. As
the controlling valve L is subjected on one side to a.constant load, and allows steam
to pass it from the boiler until the pressure exerted on the cut off valve equals the
boiler pressure, minus a pressure equivalent to the load placed on the valve by the
spring, it will be seen that the pressure exerted on the cut off valve will increase or
decrease as the boiler pressure increases or decreases. The result is that the
increased or decreased boiler pressure tending to lift the admission valve, and by
its means the cut off valve, is balanced by the increased or decreased pressure acting
on the cut off valve and tending to close the admission valve, .so that a constant
pressure is maintained on the back of the admission valve, and the pressure in the
receiver will be maintained practically constant.
In the operation of this arrangement steam will pass into the chamber L² until it
attains sufficient pressure therein to push, with the assistance of the spring L', the
valye Lagainst its seat. Obviously this obtains when the pressure of steam in L'
exceeds the difference between the boiler pressure and the pressure on the valve L
due to the spring L'. In other words the steam in the chamber L has a pressure
less than the boiler pressure by a definite amount depending upon the spring. This
pressure acts on the upper side of the cut off valve or piston. K the lower side of
which in this instance is partly exposed to atmospheric pressure, through the
orifice K. The cut off valve or piston K is in connection by the spindle K* with
the admission valve K¹ the two being of equal area.
The spring L of the controlling valve L may be graduated so that the pressure
in the receiver can be readily increased to a given extent when it is desired to
increase the power of the engine. For this purpose the parts may be so arranged
that they can be conveniently worked from the footplate. L. is a collar on the
spindle K; it is arranged to work in a chamber L in communication with the
atmosphere, and serves to limit the upward. movement of the valve K
A pressure gauge may be provided in any convenient part to indicate to the
engine driver, the pressure of steam in the receiver.
By the arrangements described with reference to Figs. 7, 8 and 9, a desired
constant pressure can always be maintained in the receiver and on the low pressure
piston, independently of the rise or fall of the boiler pressure so long as that
pressure is above the pressure required in the receiver. The power developed by
the high and low pressure cylinders can also by this means be regulated and made
equal, or the power developed by the low pressure cylinder can be made greater
than that developed by the high pressure cylinder. The steam emitted from the
exhaust pipe will also be constant for any given point of cut off so that the action
of the blast on the fire will be maintained correspondingly constant during the
working of the engine.
In the modified valve arrangement shewn in Fig. 10 the cut off valve or piston K'
is equal in area to the difference between the areas of the valve K and the
spindle K. In this case the pressure in the receiver would also be maintained
constant and practically equal to that which would be required to lift the valve L
against the spring L'. As a matter of fact it would be greater than this latter
pressure by a definite amount which is equal to that of one atmosphere.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. In compound engines, the arrangement of two valves such as H & H', one of
which controls a passage between the receiver and one end of the high pressure

page_text: cylinder, whilst the other valve controls a similar passage connecting the receiver
with the other end of the high pressure cylinder, these valves being each so arranged
that it opens when the receiver pressure exceeds the pressure in its end of the
cylinder but shuts directly the pressure in the said end of the cylinder rises above
the pressure in the receiver, so that on starting the engine, should the high pressure
distributing valve cover both steam ports, steam pressure admitted to the receiver
by a reducing valve simultaneously with the opening of the engine regulator will
act upon and open the valves H & H and allow steam at the pressure which
obtains in the receiver to act upon both sides of the high pressure piston so as to
place that piston practically in equilibrium and enable the engine to be started by
steam at the receiver-pressure acting on the low pressure piston, and should the
high pressure distributing valve be in a position to admit high pressure or boiler
steam to one side of the high pressure piston, the receiver steam will be able to pass
to the other side of that piston and counteract the force of the high pressure steam
to an extent proportionate to the difference between the two steam pressures whereby
a steady starting of the engine without shock is effected in any position of the slide
valves, substantially as herein described.
2. In a compound engine, the combination with the high and low pressure
cylinders and the receiver located between these cylinders, of a reducing valve for
automatically admitting steam to the receiver, and non-return valves for controlling
the passage of steam from the receiver to each end of the high pressure cylinder
substantially as described.
3. For automatically admitting boiler steam at a reduced pressure to the receiver
located between the high and low pressure cylinders of a compound engine, a
reducing valve comprising an admission valve subject on one side to the action of
boiler steam, a cut-off valve subject to the action of steam at a lower-pressure, and a
loaded controlling valve adapted to control the steam at lower pressure, the
arrangement being such as to maintain a practically constant pressure in the receiver
-notwithstanding-considerable-variation-in-boiler-pressure-substantially-as-herein-
before described
4. In a compound engine, a reducing valve_comprising_an_admission_vălve, a
cut-off valve and a controlling valve, these valves being constructed, arranged and
operating substantially as hereinbefore described with reference to and shewn in
Figs. 7, 8 and 9, or modified according to Fig. 10 of the drawings annexed for the
Burnose_anecified