IMPROVEMENTS IN STEAM ENGINES.
Year: 1875

page_text: LETTERS PATENT to Adam Scott Cameron, of the City and State of
New York, United States of America; now of No. 8, Southampton
Buildings, London, Engineer, for the Invention of "IMPROVEMENTS
IN STEAM ENGINES.'
"
Sealed the 9th April 1875, and dated the 4th February 1875.
PROVISIONAL SPECIFICATION left by the said Adam Scott Cameron
at the Office of the Commissioners of Patents, with his Petition,
on the 4th February 1875.
I, ADAM SCOTT CAMERON, of the City and State of New York,
United States of America, now of No. 8, Southampton Buildings,
London, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
This Invention relates, first, to improvements in expansion gear for
steam engines working with slide valves; this expansion gear is so
constructed and arranged that a steam engine in which it is employed is
not only made to work expansively, thereby securing a great saving of
fuel, which owing to the high price of coal is a most desirable con-

page_text: sideration, but it also serves when attached to the governor to regulato
the speed of the engine with great accuracy by cutting off the steam at
such a point as will ensure the exact supply necessary to perform the
work, and this it will do automatically, however variable may be the
load on the engine; the necessity of a throttle valve is thus obviated.
According to this part of the said Invention I employ cut-off valves in
combination with the main slide valve of a steam engine, steam being
admitted to the cylinder of the engine through openings in or through
the said main slide valve, which openings are controlled by the said
cut-off valves at any point throughout the whole length of tho stroke;
the operation of these cut-off valves is instantaneous, thereby avoiding
loss of power by the "wire drawing" of the steam, which takes place
when a valve is closed gradually.
By this Invention I obtain by the use of one eccentric only certain
motions which have peculiar relations to each other, and I thereby
obviate the necessity for a second eccentric. The said cut-off valves are
balanced by admitting steam below them, while they are exposed to
pressure from above before the operation of opening them commences.
I connect the governor to the cut-off mechanism by a device which
renders each of the parts free to perform its various offices while subject
to movements in contrary directions.
The rod of the said eccentric is connected to the slide valve spindle as
usual, but the said rod has an arm extending from it at the point
whereby it is connected to the said spindle, which arm has a vibrating
motion corresponding with that of the eccentric. The said vibrating
arm is connected to a rod which passes through a tube or sleeve and is
secured with collars fixed on the said rod. As the latter is moved to and
fro by the vibrating arm of the eccentric the sleeve is moved with the
said rod. The said sleeve is connected by a rack and pinion with the
governor, and is turned on its axis by the action of the said governor.
The pinion is elongated to permit the same to move endwise without
disconnection with the rack. The said sleeve has two cam wings which
are arranged to come in contact with the spindles of small valves that
control the action of the said cut-off valves.
These cut-off valves are plates fitted to work on the back of the main
slide valve over apertures in the same for the admission and exhaust of
the steam. Each of these plates has fixed or formed on its back or outer

page_text: C
WHICH is a piston, whose rod extenus
through one end of the said small cylinder, and is secured to a lug fixed
on the back of the said slide valve. This piston rod has no stuffing box,
so that steam can enter the cylinder by the hole through which the said
rod passes. The aforesaid small controlling valves open and close the
passages between the steam space in these small cylinders and the
exhaust passage of the slide valve.
The said small controlling valves are provided with two seats, and.
between the two seats a port communicates by a passage extending
through the cut-off valve to its face, with a passago extending through
the main slide valve into the exhaust cavity of the same. The exhaust
passage through the main slide valve is clongated, so that it will com-
municate with the opening through the cut-off valve, no matter at what
point of its movement the cut-off valve may be. Another other passage
forms a communication between the small valve and the bore of the
cut-off valve cylinder, and enters the bore of the said cylinder a short
distance from the bottom, so that steam will be confined therein and
" cushion "the valve.
'
When by the motion of the slide valve either of the controlling valves
is brought in contact with the corresponding graduated wing on the
aforesaid sleeve and the valve is opened a communication is made
between the two aforesaid passages and enough of the steam confined
behind the piston escapes to cause the cut-off valve to move and close
the aperture in the main slide valve. Then the pressure brings the
said controlling valve to its seats again ready for another operation.
The time at which the above operations take place is determined by
the position of the wings on the said sleeve. Supposing the same as
above described to be at the rear end of the cylinder, in the meantime,
by the same movement of the slide valve, steam is exhausted from the
front end of the said cylinder by the communication made between the
steam and exhaust ports under the slide valve, and as the said slide valve
moves the opening through the said valve at the front end passes over
the face on which the valve moves sufficiently to admit steam into the
opening from the lower side, and so balance the cut-off valve at this end.
At the same time, immediately after the operation takes place, the said
cut-off valve is brought into contact with an adjustable stop, which
prevents its moving farther, while the main slide valve by its motion

page_text: forward to its extreme range opens the cut-off valvo preparatory to
admitting steam to the front end of the cylinder.
While steam is admitted to or exhausted from either end of the
engine cylinder, that is to say throughout each stroke of the engine.
piston, the slide valve moves one half the time in one direction, and the
other half in the other direction, while the arm which actuates the
said sleeve moves throughout each stroke with the said piston. But for.
the fact that the slide valve moves as above described a fixed device
either adjustable or not, as desired, could be employed, the cut-off being
regulated by valves brought into contact with the said device by the
motion of the main slide valve whereon they are carried. For some
engines this method of working would be practicable, and I therefore
modify my Invention in this manner. But in this case as the cut-off
valves would approach the said device during one half of the engine
piston's stroke only, and the cutting off would take place in the first half ]
of the piston's stroke or not at all.
The second part of my Invention relates to means whereby a pumping
engine can be constructed to work expansively by proportioning the
movement of the pump plungers or pistons relatively to the movement
of the steam piston so as to compensate for the gradually diminishing a
pressure in the steam cylinder.
Hitherto it has been necessary to employ a weight or body of matter
in pumping engines using steam expansively, which weight after it has
been set in motion by the primary pressure of the steam continues to
move by its own momentum, and so compensates for the reducing
pressure of steam in the cylinder.
In what are known as "Cornish" engines this weight is generally
furnished by the pump rods, or weights are attached to the piston or
other part of the engine, and in rotative engines the fly wheel is employed
to accomplish the same purpose. But as this moving matter renders
engines in which it is employed costly not only in themselves but also
in their foundations and other accessories, and moreover makes them
liable to accidents and unavailable for high speed, it is very desirable to
avoid the necessity for the same. For this purpose I employ the
following mechanism and arrangement of parts. The steam cylinder is
placed parallel with the pump or pumps, and its piston rod is connected
with an arm which is fixed on a shaft, and which receives from the said

page_text: piston rod a rocking or vibrating motion. The arc described, by the
extremity of the said arm, is the part of the circle which most nearly
coincides with the centre line of the said steam cylinder.
The aforesaid rocking shaft has also fixed on it arms for operating the
pump plungers. I prefer to have two pumps in combination with one
steam cylinder. And the said arms are so arranged that each one moves
from a point in or nearly in the line of the pump's axis to a point at a
right angle or nearly so to the said line.
The arms connecting with the steam and pump cylinders may be in
this manner so arranged with regard to their lengths and relations to
each other as to conform almost exactly to the power represented by the
expanding steam in the steam cylinder. An expansion diagram may be
laid down and the arms proportioned to correspond with the same.
Any suitable expansion gear may be employed in combination with
this part of my Invention.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Adam Scott Cameron in the Great Seal Patent
Office on the 4th August 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ADAM
SCOTT CAMERON, of the City and State of New York, United States of
America, now of No. 8, Southampton Buildings, London, Engineer,
Bend greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of February, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Adam Scott Cameron, Her special
licence that I, the said Adam Scott Cameron, my executors, admini-
strators, and assigns, or such others as I, the said Adam Scott
Cameron, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
'

page_text: Britain and Ireland, the Channel Islands, and Ise of Man, an Inven-
tion for "IMPROVEMENTS IN STEAM ENGINES," upon the condition (amongst
others) that I, the said Adam Scott Cameron, my executors or admini-
strators, by an instrument in writing under my, or their, or one
of their hands and seals, 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 Adam Scott Cameron, do hereby
declare the nature of my 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
Drawing forming a part of this Specification :-
This Invention relates, first, to improvements in expansion gear for
steam engines working with slide valves. This expansion gear is so
constructed and arranged that a steam engine in which it is employed is
not only made to work expansively, thereby securing a great saving of
fuel, which owing to the high price of coal is a most desirable con-
sideration, but it also serves when attached to the governor to regulato
the speed of the engine with great accuracy by cutting off the steam at
such a point as will ensure the exact supply necessary to perform the
work; and this it will do automatically however variable may be the
load on the engine. The necessity of a throttle valve is thus obviated.
According to this part of the said Invention I employ cut-off valves
in combination with the main slide valve of a steam engine, steam being
admitted to the cylinder of the engine through openings in or through
the said main slide valve, which openings are controlled by the said cut-
off valves at any point throughout the whole length of the stroke. The
operation of these cut-off valves is instantaneous, thereby avoiding loss.
of power by the "wire drawing" of the steam which takes place when a
valve is closed gradually.
By this Invention I obtain by the use of one eccentric only certain
motions which have peculiar relations to each other, and I thereby
obviate the necessity for a second. eccentric. The said cut-off valves are
balanced by admitting steam below them while they are exposed to
pressure from above before their opening commençes. I connect the

page_text: governor to the cut-off mechanism by a device which leaves each of the
parts free to perform its various offices while keeping it subject to
adjustment in contrary directions.
The rod of the said eccentric is connected to the slide valve spindle as
usual, but the said rod has an arm extending from its point of connection
to the said spindle, which arm has a vibrating motion due to the motion
of the eccentric. The said vibrating arm is connected to a rod or spindle
which passes through a tube or sleeve, and is secured thereto with
capability of adjustment therein by collars fixed on the said rod. As
the latter is moved to and fro by the vibrating arm of the eccentric the
sleeve is moved with the said rod. The said sleeve is connected by a
rack and pinion with the governor, and is turned on its axis by the
action of the said governor. The pinion is elongated to permit the same
to move endwise without disconnection with the rack. The said sleeve
has two cam wings which are arranged to come in contact with the
spindles of small valves that control the action of the said cut-off valves,
as herein-after described.
Figure 1 is an elevation of part of a steam engine provided with. my
improved expansion gear.
Figure 2 is a longitudinal section on the line x, x, Figure 1, shewing
the relation of the main slide valve to the ports.
Figure 8 is a transverse section of the steam chest on the line y, y,
Figure 1.
Figure 4 is a plan of one of the cut-off valves partly in section;
Figure 5 is an end view of the same.
Figures 6, 7, and 8 shew detached portions of the mechanism whereby
the said cut-off valves are operated.
Like letters indicate the same parts throughout the Drawing.
A is the steam chest or slide valve casing; B is the main slide
valve; C, C', are the cut-off valves; D, D', are pistons fitted within
small cylinders C2, C³, in the back of the said cut-off valves ;
E, E', are the controlling valves; F, F¹, are adjustable stops; G is the
winged sleeve; G₁ is the toothed pinion thereon; H is the rack geared

page_text: with the said pinion; I is the spindle which passes through. the said
sleeve; J is the excentric fixed on the shaft K; L is the rod of the
main slide valve B connected to the said excentric by the rod M; N'is.
an arm formed rigidly on the excentric rod M, and connected at N¹ with
the spindle I.
The cut-off valves C, C', are plates fitted to work on the back of the
main slide valve B over apertures in the same for the admission and
exhaust of the steam. Each of these plates has fixed or formed on its
back or outer side a small auxiliary cylinder in which is fitted a piston.
whose rod extends through one end of the said small cylinder, and is
secured to a lug c fixed on the back of the said slide valve, and therefore
the pistons D, D', are fixed relatively to the main slide valve. These.
piston rods have no stuffing boxes, so that steam can enter the cylinders.
C2, C3, by the holes through which the said rods pass.
The aforesaid small controlling valves E, E', open and close the
passages e between the steam space e¹ in these small cylinders and the
exhaust passage e of the slide valve B. Each of the said small con-
trolling valves E, E', is provided with two seats or closing faces 1, 2,
and between the two seats a port e' communicates by a passage
extending through the cut-off valve to its face with an opening e³, which a
passes through the main slide valve into the exhaust cavity of the same.
The passage e through the main slide valve B is elongated to commu-
nicate with the opening e³ through the cut-off valve C or C³, no matter
at what point of its movement the said cut-off valve may be. The
passage e forms a communication between the small valve and the bore a
of the cut-off valve cylinder, and enters the bore of the said cylinder a
short distance from the bottom, so that steam will be confined therein
and cushion the piston.
Assuming the parts to be in the position represented in Figure 1, the
excentric J moving in the direction indicated by the arrow, the slide a
valve B will be moved from right to left and steam will be admitted to the
steam cylinder by the steam port at the right band end of the same.
While this operation is going forward the stem of the controlling valve
E' is approaching the cam or wing on the right hand end of the
sleeve G.
When by the combined motions of the slide valve B and the sleeve G,
the controlling volvo El is brought
3

page_text: graduated wing G on the aforesaid sleeve G and the valve is
opened, a communication is made between the two aforesaid passages,
and enough of the steam confined behind the piston D' escapes to
sufficiently overcome its equilibrium to move the cut-off valve C' to the
right, and close the aperture in the main slide valve. As the valve C¹
moves to the right the pressure on the large face of the valve E' brings
the said valve to its seats again ready for another operation.
The time at which the above operations take place is determined by
the position of the wings G³, G³, on the sleeve G. In the meantime by
the same movement of the slide valve steam is exhausted from the
cylinder at the left hand end of the same by the communication made
between the steam and exhaust ports under the slide valve B, and as
this slide valve moves to the left (as will be seen by referring to
Figure 2), the opening through the said valve at the left hand end
passes over the face, on which the valve moves sufficiently to admit
steam into the opening from the lower side, and so balance the cut-off
valve C. At the same time immediately after this operation takes place,
the said cut-off valve is brought into contact with the adjustable stop F
which prevents its moving farther, while the main slide valve B by its
motion forward to its extreme range on the left, opens the cut-off valve
preparatory to admitting steam to the left hand or front end of the
cylinder. The same action takes place at both ends of the cylinder
alternately.
An important effect of the above described construction is the
following action, namely, while steam is admitted to or exhausted from
either end of the engine cylinder, that is to say, throughout each stroko
of the engine piston the slide valve moves one half the time in one
direction, and the other half in the other direction, while the arm N
which actuates the sleeve G moves it throughout the whole length of
each stroke of the said piston towards the valves E and E¹ alternately,
thus controlling the cut-off valves at any point of the stroke. But for
the fact that the slide valve moves as above described a fixed devico
either adjustable or not as desired could be employed the cut-off being
regulated by valves brought into contact with the said device, by the
motion of the main slide valve whereon they are carried. For some
engines this method of working would be practicable, and I therefore.
modify my Invention in this manner. But in this case as the cut-off
valves would approach the said device during one half of the engine

page_text: piston's stroke, only the cutting off would take place in the first half of
the piston's stroke or not at all.
The second part of my Invention relates to means whereby a pumping
engine may be constructed to use steam expansively, by so arranging
the parts that the resistance to be overcome by the pressure applied to
the motive piston will gradually decrease towards the end of its stroke,
thus accommodating the gradual reduction of pressure in the steam
cylinder by expansion.
Hitherto it has been necessary in practice to employ a weight or body
of matter in pumping engines, using steam expansively, which weight
after it has been set in motion by the primary pressure of the steam
continues to move by its own momentum, and so compensates for the
reducing pressure of steam in the cylinder.
"
In what are known a as " Cornish engines this weight is generally
furnished by the pump-rods; or weights are attached to the piston or
other moving parts of the engine, and in rotative engines the fly wheel
accomplishes the same purpose. But as this moving matter renders
engines in which it is employed costly, not only in themselves but also
in their foundations and other accessories, and moreover makes them
liable to accidents and unavailable for high speeds, it is desirable to
avoid the necessity for the same. For this purpose I employ the
mechanism and arrangements of parts illustrated in Figure 9, which
shows a direct acting steam pump similar in appearance to the special
steam pump manufactured by Tangye, Brothers, of Birmingham, except
that the steam cylinder O and the pump cylinder P are placed far.
enough apart to allow room for the movement of the cross head S between
them, which cross head operates the plunger pump T. The cylinder
of the plunger pump is mounted on the top of the main or working
cylinder P, which main cylinder is fitted with a suitable piston and valves
and is double acting; this main cylinder with its piston and valves moves
the fluid, and does the work of the pump, while the said plunger pump T
is a part of the arrangements by which steam may be used expansively;
its movement does not contribute directly to the amount of fluid
pumped.
The operation is as follows:-Let it be supposed that the steam
pistons stands at the extreme back or right-hand end of the cylinder, as
in Figure 9. as it begins to move to the left. Besides moving the

page_text: main piston forward to do the work of the pump it also moves the
plunger T' of the plunger pump downwards, and as the plunger pump
cylinder is in communication (beneath. the plunger) with the fluid in the
delivery column of the pump, it follows that its downward movement
requires an amount of steam pressure beyond that necessary to balance
the load on the main pump piston; and as this piston advances from
right to left the movement of the plunger piston relatively to the main
piston gradually diminishes until it arrives at the half stroke, beyond
which point the plunger or piston T' begins to rise, and the pressure on
its. lower surface acts to assist the steam in moving the main piston
forward. The influence of the movement of this plunger piston in con-
nection with the main piston allows a high pressure of steam to be used
at the commencement of the steam piston's stroke, which pressure may
be reduced by cutting off the connection of the steam with the boiler
near the commencement of the stroke, and allowing it to expand down
to or nearly to atmospheric pressure at the termination of the stroke of
the main piston, great economy being thereby insured. The operation
is the same during each stroke of the main piston.
By inserting a suitable valve or cock in the pipe which connects the
fluid in the plunger pump T with the fluid in the discharge or column
pipe, through which the fluid moved by the main pump is discharged
the attendant may at any time by simply moving this valve or cock, and
by disconnecting the cut-off gear attached to the steam cylinder cause
the engine to work non-expansively in the manner of an ordinary direct-
acting steam pump. The proportion and arrangement of the levers to
move the plunger T¹ of the plunger pump may be adapted to suit the
pressure of steam or point of cutting off which it may be considered
desirable to establish.
Instead of the above described plunger pump to permit the use of
steam expansively by storing up a power at the commencement of the
steam piston's stroke to be given out towards the end of the stroke

page_text: In Figure 10 I have shown another modification of my improvements,
whereby a steam pumping engine may be worked expansively. The
steam cylinder O is placed parallel with the pump or pumps P, and the
piston rod O' is connected with an arm Q, which is fixed on a shaft R,
and which receives from the said piston rod a rocking or vibrating 5
motion. The arc described by the extremity of the arm Q is the part
of the circle which most. nearly coincides with the centre line of the
said steam cylinder O. The aforesaid rocking shaft R has also fixed on
its arms P1, P2, for operating the pump plungers P³.
I prefer to have two pumps in combination with one steam cylinder; 1
as shown, the said arms P1, P2, being so arranged that each one moves
from a point in or nearly in a line of the pump's axes to a point at a right
angle or nearly so to the said line.
The arms connecting with the steam and pump cylinders O, P, may
be in this manner so arranged with regard to their lengths and relations 1
to each other as to conform almost exactly to the power represented by
the expanding steam in the steam cylinder. An expansion diagram may
be laid down and the arms proportioned to correspond with the same.
Having thus fully described my said Invention, and the manner of
performing the same, I wish it understood that I do not confine myself 2
to any particular form of expansion gear, but may use any form or con-
struction thereof most convenient for my purpose in combination with
my improvements, and I claim,-
First. In a steam engine the employment in combination with the
main slide valve or valves of cut-off valves operated by auxiliary pistons 2
and cylinders, as above described.
Second. Operating the cut-off valves of steam engines in connection
with auxiliary pistons and cylinders in such a manner that the said
cut-off valves are opened by a positive motion derived from the engine
and closed by the action of said auxiliary cylinders and pistons, as above 3
described.
Third. The employment in combination with the said cut-off valves
and the auxiliary cylinders and pistons which operate them of auxiliary
valves for controlling the egress of steam from the said auxiliary
cylinders, and thereby closing the cut-off valves, as above described.
.

page_text: -
Fourth. The employment in combination with cut-off valves and the
mechanism which controls them of a motion derived from the eccentric
which drives the main valve when such motion does not coincide with
the motion of the main valve.
Fifth. The sleeve carrying the toothed pinion and inclined wings, or
other equivalent devices, constructed and operating as described.
Sixth. The employment of a governor in combination with a cut-off
valve gear embodying the improvements herein set forth.
Seventh. In a steam pumping engine in which steam is used
expansively the working parts, as herein set forth, so arranged and
operating that the resistance to be overcome by the pressure on the
steam piston corresponds, or nearly corresponds, at all points of the
piston's stroke with the pressure of steam in the steam cylinder.
Eighth. A steam pumping engine in which steam may be used
either expansively or non-expansively, as herein set forth.
In witness whereof, I, the said Adam Scott Cameron, have here-
unto set my hand and seal, this Twelfth day of February, in
the year of our Lord One thousand eight hundred and seventy-
five
Witness,
JAS. EDWARDS,
8, Southampton Buildings,
London.
A. S. CAMERON. (L.S.)