CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1844

page_text: ALD
THEDE
CHAPMAN, of Claremont Terrace, Strangeways, Manchester, in the County of
Lancaster, Engineer; send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Fourth day of June, in the seventh year of Her reign, did,
for Herself. Her heirs and' successors, give and grant unto me, the said George
Chapman, Her especial licence, full power, sole privilege and authority, that
I, the said George Chapman, my executors, administrators, and assigns, or
such others as I, the said George Chapman, my executors, administrators,
or assigns, should at any time agree with, and no others, from time to time
and at all times during the term of years therein expressed, should and law-
fully might make, use, exercise, and vend, within England, Wales, and the
Town of Berwick-upon-Tweed, my Invention of "CERTAIN IMPROVEMENTS IN
STEAM ENGINES;" in which said Letters Patent there is contained a proviso
that I, the said George Chapman, shall cause a particular description of the
nature of my said Invention, and in what manner the same is to be performed,
to be inrolled in Her said Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part'
recited' Letters Patent, as in and by the same; reference being thereunto had,
will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
George Chapman, do hereby declare the nature of my said Invention; and in
what manner the same is to be performed, to be fully described and set
forth in and by the following statement and Specification thereof, reference

page_text: being had to the accompanying Drawings (which I declare to belong to and
to form part thereof), by the letters and numeral figures marked thereon for
the purpose of such reference, that is to say :-
My said Invention consists in and has reference to the principles of con-
struction and the modes of arrangement of the mechanical parts, and also the
several combinations of the same, as such several matters are herein-after
described and set forth, as regards my application of the same to the objects
set forth and referred to in and by the title of the Letters Patent granted
unto me, the said George Chapman, as hercin-before recited. The particular
nature and intention of my said Invention I declare to consist in forming and
constructing apparatus or machinery for the purpose of improving the working
action and practical effect of steam engines, and this in the following parti-
culars: Firstly, in improved apparatus and methods of adjusting and regu-
lating the passage of the steam between the boilers of steam engines and their
working cylinders; and, secondly, in an improved method of adjusting and
regulating the supply of cold or condensing water to the condensing vessels of
steam engines, my intention therein being to produce in the resulting effect of
the same a better vacuum in the working cylinder of the engine.
I declare that my said Invention comprises two improved methods of
adjusting and regulating the passage of the steam between the boilers of
steam engines and their working cylinders. The first of such improvements
I describe as follows:-
It is well and commonly known that the supply of steam from the boiler to
the working cylinder of a steam engine is given by valves, generally deno-
minated the coffer valve, and that such valves, when single, have a port or
steam passage carried through the valve from the back to the front or sliding.
face next to the cylinder, and that such ports have a plate or cover that slides
on the back of the valve. When motion is given to such valve by the
excentric, or by other methods by which such valves are generally moved, the
aforesaid slide plate or cover is stopped in its motion with the valve. This is
caused by the pressure of the steam acting on the back of the valve by two
tappets or claws, which are attached to separate spindles, which pass through.
the steam chest of the engine at right angles to the motion of the valve.
These tappets or claws are made to change or vary their distance from each
other by the spindles on which they are fixed partially revolving on their
respective centres by means of wheels or quadrants working in each other on
the outer side of the steam chest, so as to alter or vary the distance of such
tappets or claws from each other, and so to allow the sliding plate to travel
along with the steam admission or coffer valve a greater or less distance, as

page_text: required, according to the strength of the steam in the boiler or the work
required of the engine. Now, instead of such the above-described method of
applying wheels, quadrants, spindles, and tappets or claws as aforesaid, I con-
struct an apparatus according to the following description thereof, having refe-
rence to the Figures 1 and 2 respectively in the Drawing No. 1, the Figure 1
representing a side elevation of a model of such apparatus; Figure 2, a
horizontal plan of the same. A spindle A passes through the steam chest in
the centre of its front plate, and at right angles to the motion of the valve.
The spindle works through a stuffing box B, or other suitable fitting. Upon
the inner end of such spindle is fixed a block or plate of metal C, C, C, of
elliptical or other curved shape, whose longer dimension, when it is placed in the
direction of the motion of the valve, will extend through the distance at which
two fixed pieces or ribs D, D, are placed upon the back of the aforesaid
sliding plate, which is here represented by the plate E, E, and at such dis-
tance apart as that when the elliptical or curved piece is in that position, the
sliding plate E, E, is prevented from moving with the valve, and consequently
the valve part will slide under the plate. The result of this arrangement is,
that the steam will be cut off from the cylinder at an early period. On the
other hand, if the elleptical piece or camb be turned from the position last
described until its shorter dimension be opposite to the two ribs on the back
of the sliding plate, then the camb does not stop the motion of the sliding
plate, but allows it to move with the valve to the full extent of its range, and
the steam is allowed to enter the cylinder, driving the full extent of the stroke.
Now the two points above described are the extreme points of the range; and,
if the spindle which carries the curved camb has a lever on its outer end, and
the governor be suitably attached to it by its levers and connecting rods, it will
so operate on the camb that it will, according to its position, either admit the
free entrance of the steam to the cylinder or wholly prevent its entrance
thereto, or admit its entrance thereto at any fractional part between the two
extremes. The steam that has already entered will then expand and effect
the remainder of the stroke.
In the Figure 2 the camb is shewn in the first position, above described
at C¹, C', and in the second position described at C³, C². The steam passages
are shewn in the Figure 1, at G, G, when they are at one extremity of their
course or motion in the first position described, and at H, H, when they are at
the other or opposite extremity of their course or motion.
The Figure 2 of this Drawing represents a plan view of the Figure 1, in
which the corresponding parts are respectively marked with the same letters of
reference.

page_text: Now I desire it to be understood that I do not herein claim as of my
invention the process or method of cutting off the steam by the above-
described valve and sliding plate; but that I do claim as of my invention thie
above-described elliptical or other curved. camb, fixed on a spindle or centre at
right angles to the traverse of the valve, so as to stop the sliding cover or
plate at an earlier or later part of its course by the change or difference of
position of the said camb, effected either by the above-described lever. on the
outer end of the spindle connected. to the governor, or fixed. to be moved by
hand, and clamped or held in any of its positions required, and this instead
of the herein-before described method by or through the means of tappets,
claws, wheels, or quadrants.
The second method of such my improvements I describe as follows:-It
consists in the second method of cutting off the supply of steam to the working
cylinder at any fractional part of the stroke, instead. of using the apparatus
usually called an eccentric to communicate motion to the steam valve, accord-
ing to the usual method. I give motion to the steam valve in the following
manner I place a metal wheel or circular plate P (Figure 5, Drawing No. 2,)
on the principal. shaft or axle, or on any other suitable shaft, or axle of the
engine, which may be fixed to the engine for, the purpose. I form one side.of
such wheel or circular plate with a projecting ring at its centre, of suflicient
substance to allow it to be keyed or otherwise fastened to the aforesaid shaft
or axle. On the same side of the plate, at its edge, there is a projecting
rim P', the outer edge of which rim stands at right angles to the face of the
plate; but the inner, edge of the rim projects from the plate at an angle of
about 80 degrees. A second wheel or circular plate N fits into the wheel or
plate P, both at its boss, where it is keyed on to the shaft, and also at the
bevilled inner face of its projecting rim. The two flat faces of the wheels or
plates are not to be in contact. The projecting boss of the plate P,. that is
keyed on to the shaft, projects so far through the plate N as to admit a ring
and screw put, a thread or male screw being cut in its end for the purpose of
screwing the two plates N and P into contact, as seen at Z. On the inner
side of the plate N, I place a projecting piece of metal, passing through an
opening or slot in the plate P, which slot is made in its figure a portion of a
circle generated from the common centre of the two plates N and P, and it
extends to nearly half the circumference of the same, and is made of sufficient
width to allow the projecting piece of metal of the plate N to traverse in it
from end to end. Upon the extremity of this piece, and on the outer face of
the plate P, I place the heart-shaped camb R (shewn in Figure 6), which
then has its lower or inner face laying in the same plane with the upper or

page_text: outer face of the plate P, and being at liberty to move concentrically with the
wheels N and P with and whenever the plate N moves on its centre, but
independent of the wheel P; and on the wheel P, I fix the trapezoidal pieco
or camb V (Figure 6). Now these two pieces R and V, when, by motion of
the plate N, the heart-shaped piece R is brought into close contact with the
piece V by one of its edges, then they together form a compound camb, or a
camb compounded of those two pieces R and V, and when a circular motion
is given to the shaft on which they are fixed or set, and properly connected
by levers and connecting rods, in the common and well-known manner to the
steam admission or distributing valve of the engine, will move it as shall be
required, but it will move it only all at one motion, as is commonly done
when the engine does not work expansively; but when it is desired to cut the
steam off from entering the cylinder at any fractional part of the stroke,
then it is effected by the following arrangement:-The inner faces of the
plates N and P are placed at a small distance apart, leaving an interval
between them sufficient to admit a segment of a bevil wheel (shewn at X, in
the Figures 4 and 5), set on the inner side of the plate N, to gear into and
act upon the segment wheel X. I fix a bevil pinion (Y, in Figures 4
and 5,) to work between the two plates N and P, its spindle being fixed in
the plate that is keyed on to the shaft. The spindle of the pinion Y projects
through the projecting rim of the last-mentioned plate at right angles to the
principal shaft, and upon the outer end of this shaft I set a round boss or
head, about the circumference of which there are fixed projecting radial pins.
or teeth; (this is seen at L, in the Figures 1, 2, 3, 4, 5, and 6. Parallel with
these projecting pins or teeth I place a sliding piece or plate S (seen in the
Figures 2 and 3, one extremity of which is attached to the governor. The
sliding piece S slides in sockets, one of which is shewn at S*, in Figure 3.
The piece S has two or more pins T, T, Figure 2, projecting from it at
right angles, and at a distance apart that will admit the boss L, with its
radial pins or teeth, to.. pass. through or between them without coming into
contact with them. But if the sliding piece or bar S is moved in its support-
ing sockets in the direction of its length, then one of the projecting pins T, T,
will fall into contact with and act upon the radial pins or teeth of the boss L,
and will then cause the boss to make a certain portion of a revolution on its
axis; and, consequently, the bevil pinion Y, together with the plate N already
described, will also make a certain portion of a revolution on its centre at
each time that either of the projecting pins T, T, of the sliding piece S come
into contact with the radial pins of the boss L, and thus cause the steam to
be cut off earlier or later, as may be required, until the governor has, by this
adjustment, moved the sliding piece S beyond the action of the radial pins or

page_text: teeth of the boss L, and which the governor will do when the engine is going
at the required speed. The manner in which the steam will be cut off from
the boiler to the cylinder at any fractional part of the length of the stroke,
is as follows, that is to say:-The two before-described plates N and P, with
their two projecting camb pieces R and V on one side or face of them, would
only cause the sliding or other valves to move so as to reverse the passage
of the steam to the cylinder from one end to the other at one shift, but when
it is desired to cut off the steam at any fractional portion of time required,
then the valve must be moved twice in each upward and downward motion
of the piston, and to effect this the two projecting pieces or cambs N and P
being placed on two separate plates or centres, and one of them being fixed
while the other is moveable, these two cambs being of figure to form and
compose between them a compound camb or wiper of the figure shewn in the
Figure 6, where the two pieces R and V are shewn in close contact with each
other by their edges, they will, in that state, move the valve entirely at one,
shift; but by moving the plate N by the operation of the bevil wheel X and
the boss L, the portion of the compound camb that is fixed to the plate N
will be separated from the portion that is upon the plate P, so that the former
portion will fall in contact with the apparatus that moves the steam admission
valve at an earlier period than before. The figures and the dimensions
respectively of the separate pieces which compose the compoud camb being
such that one will operate to cut off the steam from the boiler to the cylinder,
but will not entirely close the eduction port or passage from the other or
exhaust end of the cylinder to the condenser, whilst the other portion will
move the valve the remaining space requisite to commence the return stroke.
I declare that what I claim as of my invention in this the last above-
mentioned part of this my Specification, is the method of shifting one part or
portion of the compound camb or wiper by the action of the governor whilst
the engine is in action, so as to constitute and be a self-acting adjustment to
accomodate itself to the speed or work required, and this in the manner as I
have herein-before set, forth and described the same. I would state that the
same apparatus, may be constructed to be set by hand to any required position
or adjustment, and clamped in such position whilst the engine is in action, in
the cases where no governor is used.
I declare that the second part of my Invention consists in a method of
regulating the supply of condensing water to the condensers of steam engines
so as to effect a more perfect vacuum in the working cylinder of the engine.
I effect and perform this in manner following, that is to say:-Instead of
allowing the condensing water to flow into the condenser uninterruptedly,
and at an uniform rate during the entire length of the stroke of the engine,

page_text: which has been the practice hitherto, I allow the larger portion of the
entire quantity of the condensing water (in general practice from about one
half thereof to about seven eighths) to enter the condenser at the same time
that the steam is issuing from the working cylinder, after which time, or after
such admission, I stop the full passage of the condensing water, and allow
only a small portion thereof to issue in a constant stream into the condenser ;
and the purpose for which I have devised and do execute this improvement is,
to counteract or provide against any leakage of steam past the steam piston or
valves, or other places or fittings, into the condenser of the engine. I employ
one or more valves, to effect the same purpose by a motion from the engine,
to shut off the condensing water at any point of time, and to stop its discharge
into the condenser at any fractional part of the stroke of the piston that may
be required, and the smaller continuous stream, herein-before described, may
be allowed to issue into the condenser by a tap, or slide, or other ordinary
means by which the supply may be regulated, as it is commonly performed,
but it will require the continual supply of a smaller quantity than heretofore
has been ordinarily used. A method which I find practically proper and
beneficial for giving the supply of condensing water at any fractional part of
the stroke of the piston, is, to provide a rotary motion at the same rate
of speed as the crank shaft, or to take the crank itself, and to fix upon it a
camb or wiper of two teeth, which teeth are 'to be' constructed and formed
to act on a lever or levers, and connecting rods, or other motions attached
to the water admission valve into the condenser. The shape of the teeth
of such camb or wiper must be on one of its sides or edges, a straight line
radiating from the centre; the other or opposite side or edge of the tooth
must be formed in a spiral curve springing from the root of the tooth, and
developing itself to the outer point of the tooth. These two teeth act upon a
lever, or other connection with the water valve, so as to operate to open it.
I further describe this by reference to the Figure 3 of the Drawing No. 1,
in which A represents the camb or wiper, which revolves in the direction
indicated by the arrow a. B, B, mark the teeth or lifting parts, one side of
which is formed straight; this side lifts the lever C, which is connected by
rods or other requisite communication with the injection valve or tap H; the
other side of the tooth is formed of spiral curvilinear figure from root to
point, as shewn in the Figure. Now if the end of the lever C, on which the
camb or tooth acts or lifts at its revolutions be always at the same distance
from the centre of the camb before the camb commences its action upon it at
each of its strokes or semi-revolutions on its shaft, it would at each such
stroke hold the water admission valve open in the same portion of such stroko

page_text: before it would allow it to close, and so shut off the water; but if, instead of the
lever C, upon which the camb acts, being fixed permanently at one point, it is
set on the extremity of another lever D, which, as it turns on its centre,
advances the lever C nearer to or withdraws it further from the camb A; then,
consequently, the lever D has the effect, in whatever position it may be fixed, of
holding up the injection valve during a longer or shorter portion of each stroke
in proportion to what part of the curve of the camb A the lifting lever is then
acting upon; for if the lever C. be near to the centre of the camb, it will not
allow the valve to close at all, but, on the contrary, if the lever C should be
withdrawn so far that the smaller ends of the camb teeth do not reach or touch.
it, then it is evident the valve will not be opened at all. These two points
are the two extreme points of the actions, and any intermediate point between
these two may be accurately ascertained by shifting the lever D, and clamping;
it at the proper position when it is obtained.
Having now described and set forth the nature of my said Invention, and
also the means by which I carry the same into practical effect, I declare that
I claim as of my Invention all those principles of construction and mechanical
arrangement; with the mode of application of the same, as I have herein-before:
set. forth. and clained the same at the close of the statement. and Specification
of each division or branch of my said Invention respectively..
In witness whereof, I, the said George Chapman;. have hereunto set
my hand. and seal, this Second day of December, in the year of our
Lond