MY INVENTION OF CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1844

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
PETRIE, of Rochdale, in the County of Lancaster, Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-second day of May, in the seventh year of Her reign;
did, for Herself, Her heirs and successors, give and grant unto me, the said
James Petrie, Her special license, full power, sole privilege and authority,
that I, the said James Petrie, my executors, administrators, and assigns, and
such others as I, the said James Petrie, my executors, administrators, and
assigns, should agree with, and no others, from time to time and at all times
during the term of years therein expressed, should and lawfully might make,
use, exercise, and vend, within England and Wales and the Town of Berwick-
upon-Tweed, "MY INVENTION OF CERTAIN IMPROVEMENTS IN STEAM ENGINES;" in
which said Letters Patent is contained a proviso that I, the said James Petrie,
shall cause a particular description of the nature of my said Invention, and
in what manner the same is to be performed, to be enrolled in Her Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part 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
James Petrie, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, is particularly described and

page_text: ascertained in and by the Drawings hereto annexed, and the following explana-
tion thereof, that is to say :-
My improvements in steam engines are, firstly, the application of a certain
novel arrangement or construction of apparatus or mechanism to ordinary
steam engines for the purpose of "cutting off" the steam when working steam
engines expansively, and consist chiefly in the particular application of and
mode of working certain sliding valves or "cutting off" plates placed in the
inside of and worked in connection with the common D or slide valves of
steam engines, which said sliding valves or "cutting off" plates are worked by
means of a moveable cam or tappett in addition to the ordinary eccentric or
crank used for working the D valves.
The peculiar advantages to be obtained by the application of my Invention
are, firstly, the "
cutting off" the steam close to the nozzle of the steam
cylinder; secondly, the sliding valves or "cutting off" plates being at the
time of motion nearly in an equilibrium of pressure, but little power is required
to work them; thirdly, smoothness and ease of motion, as the parts which
require to be suddenly set in motion are very light in their construction;
fourthly, the ordinary motion (by eccentric) of the D valves being retained,
the improved method of admitting steam into the cylinder may be used, so as
to avoid the concussion caused when it is admitted too suddenly.
The second feature of novelty in my improvements in steam engines consists
in a method of connecting the aforesaid "cutting off" plates or slides (and
their operating apparatus worked in connection with the common D valves)
with the ordinary "governor" of the steam engine, so that the steam may be
cut off" earlier or later by the action of the " governor, as the power
required is less or more, which will ensure the maximum of expansion,
thereby economizing steam, and consequently fuel, to the utmost extent.
"
Having now described the nature of my said Invention, I will proceed to
illustrate the mode of carrying the same into practical effect. And in order
that my improvements may be perfectly understood, I have attached to these
presents three Sheets of Drawings representing the mode of applying my
improved apparatus to steam engines, and also separate views of the same
shewn detached from the engine, having marked the Figures with letters
of reference corresponding with the following description of the apparatus;
and for the sake of more distinctly pointing out my improvements they are
shewn as shaded with colour, the ordinary parts in connection therewith being
drawn in outline.
In Sheet 1, Fig. 1 is the side elevation of the cylinder of an ordinary
stationary steam engine, shewing a section taken through the valve boxes of

page_text: the same; and Fig. 2 is a front elevation of a cylinder, and the side pipes
of an ordinary steam engine, a portion of the front of the steam boxes being
supposed to be removed, and the valves shewn in section. The steam cylinder
is shewn at A, and the two D or slide valves B, B', are worked in the usual
manner by means of an eccentric or crank, and are similar in form to those
of the ordinary construction. The partitions a, a', which separate the steam
end from the eduction end, are placed near to the eduction side of the bars b, b¹,
which traverse across the ports in the facing on the nozzles c, c', of the cylinder,
so as to make sufficient room for the sliding or "cutting off" plates d, d¹; there
is also another bar e, e¹, across the face of the valve at the extremity of the
steam end; the space between the bars forms a thoroughfare or sluice f,ƒª.
These two bars are finished to a plane surface on both sides, viz., on the side
which slides on the facing on the cylinder nozzle, and also on the side enclosed
by the semicircular part of the D valve; on the last-mentioned surfaces are the
sliding plates or "cutting off" slides d, d, before mentioned. These two slides
are for "cutting" the steam, and are connected together by means of rods g, g',
passing through stuffing boxes in the bottom of the top steam box, and in the
top of the bottom box; these two sliding plates d, d', are connected with
machinery hereafter described in such a manner as to cause them to partake
of the motion of or move along with the D valves B, B', for any portion
of the stroke, and then to move on the inside facing of the D valve, so
as to close either of the openings f, f¹, and thereby cut off the steam for
the remainder of the stroke. When the sliding plate d covers the sluice f
in the face of the D valve B, as in Fig. 1, the other sliding plate d¹
is in such a position to leave the sluice f¹ in the D valve B' uncovered.
When in this position, and the D valves are moving downwards, the
sluice f is in a condition to admit steam into the bottom port of the
cylinder A, which steam will be "cut off" when the sliding plate d
closes the sluice f. When the sluice f¹ is thus closed, the sluice f will be
opened, and the D valve B is then in a condition to admit steam through the
upper port of the cylinder by the motion produced by the common eccentric
or crank, the sliding plates d, d', continuing to move along with the D valves
until the proper time arrives for "cutting off" the steam at the sluice f. In
both these cases the remaining portion of the stroke which the piston makes
after the sluices f and f¹ are closed, is effected by the expansion of the steam.
The machinery by which the "cut off" plates d, d', are moved admits of some
variation, depending upon the situation, and upon the facility with which it
be required to be altered, so as to cut off the steam at an earlier or later
portion of the stroke. When this alteration does not require to be performed
may

page_text: whilst the engine is working, the arrangement exhibited in Fig. 1, and shewn
also detached in Sheet 2, is to be adopted.
In Sheet 2, Figs. 1 and 2 are side and plan views of a common eccentric
and rod placed on a fly wheel or other shaft in a convenient situation. The
eccentric.h is made broader on the periphery or edge than usual, and has a
groove turned in it, as in common, for the reception of the clips connected to
the common excentric: rod t. This groove is close to one edge; and on the
remaining portion of the breadth is fitted a moveable cam i. The edge of this
cam is'concentric with the eccentric h, except at the two inclined portions j.j.
These inclined portions act on the friction rollers k, k, which are connected to
an elliptical ring 1, to which is attached a rod m, which leads to the "cut off"
valves d, d¹. This elliptical ring 7 is steadied by guides 'n, n, as shewn in the
Figure, so as to move only in a right line with the aforesaid rod m, to which
it is attached. This rod m is connected to a bell crank lever 'o, which is loose
on the cross shaft p, which moves the valves. This connection with the
"cut off valves is also shewn in Sheet. 1. at: Fig: 1.. A rod or link q'from
this bell crank works the shaft r, which is connected by means of links' s, s,
to the rods g, 9', before described, which connect the two "cutting off"
slides ff. The point at which the steam is cut off is varied by shifting the
moveable cam i on the common excentric h, either forwards or backwards, as
required. As the cam i revolves along with the eccentric h, and as the acting
surface of the cam is, as stated above, concentric with the eccentric, except at
the points j, j this motion will alternately draw the cam rod m backwards, and
push it forwards. With respect to the excentric rod in like manner, it will be
seen that the loose bell crank lever o will have the same motion as if it were
fast in the cross shaft p, except at the aforesaid times, and that consequently
the "cut off" slides d, d', will travel with the D valves, to which they are
attached, except at the time when they are cutting off the steam.
The second part of my improvements, namely, the mode of connecting the
"expansion apparatus".with the common "governor". of the steam engine, is
also exhibited in Sheet 2, and is of considerable importance, as a much greater
economy of working may be effected. As the power required (in working
stationary steam engines, particularly those employed for manufacturing pur-
poses) is seldom equable, it is desirable, in order to obtain the full amount of
advantage attainable, that the steam should be cut off earlier or later in the
cylinder, as the weight on the engine may vary.
In Sheet 2, Figs. 3, 4, and 5, are a plan, cross section, and side elevation of
an arrangement of apparatus adapted for the purpose. 1, 1, is a headstock or
frame which slides on a plate or bed 2, 2. This headstock is connected by a

page_text: link 3, 3, to the common eccentric rod t, by means of the studs. 4 and 5. The
stud 5 should be at or near the end of the eccentric rod. The headstock.con-
nected in this way will slide backwards and forwards in the same manner as if
it was linked to a lever on the cross shaft p, and would consequently commu-
nicate the same motion by the link 6 to a loose lever o on the cross shaft p, of
the same length as the one engaged in the "gab" of the eccentric rod, as if
the said loose lever o was fast on the cross shaft. All that is necessary now
to complete the motion of the loose lever; o is to move the link 6 backwards
and forwards. This is performed by means of a cam 7 (which is equal in
effect to the cam i in Fig. 1 and 2), which revolves on the shaft 8 bearing in
the headstock, which cam acts on friction rollers g, g, as shewn in the Figures
referred to.
:
.:
The means by which the above cam 7 is made to revolve, and also the
manner in which the whole may be controlled by the "governor," are as
follows: On the fly-wheel shaft C. is a bevil wheel 10, which drives a
pinion 11 on a shaft 12., About midway betwen the fly-wheel shaft and the
headstock is a coupling 13, which connects the aforesaid shaft 12 to another
shaft 14, by means of a hoop and sliding key, in such a manner as to allow
the shaft 14 to move backwards and forwards in the direction of its length,
the same distance that the headstock travels, (i.e., the throw of the excentric).
The other end of the shaft 14 runs in a bearing 15 attached to the headstock,
and drives, by means of the bevil wheels 16, 17, the shaft 8 .the same number
of revolutions in a given time as the fly-wheel shaft makes. On this shaft 8
the bevil wheel 18 is keyed, and communicates motion to the bevil planet
pinion 19, which is engaged in the bevil wheel 20. This last-mentioned
wheel 20 is keyed on the boss of the cam 7, and the cam is loose on the
shaft 8. The planet pinion 19 is supported, as shewn in the sectional
Figure 4, in the worm wheel 21, which is engaged in a worm 22 below.
This worm is journaled in the bottom of the headstock in such a manner as
only to allow of a motion round its own axis. This worm 21 is slotted through
(or has a key bed cut thro' its boss), and the end of a shaft 23 (in connection
with the "governor,") with a sliding key is fitted in it; its use will be described
hereafter. It is obvious that so long as the planet pinion 19 is stationary, the
wheel 20, and consequently.the cam 7, to which it is attached, will make the
same number of revolutions in a given time as the fly-wheel shaft does; and
as long as this is the case, the cam 7 will move the cutting off" slides d, d',
by the means before shewn, at one certain fixed point of the stroke of the
engine. Now, if the worm in the bottom of the headstock be made to revolve,
it will act on the worm wheel 21, which carries the planet pinion 19, and alter
16

page_text: the situation of the wheel 20 on the shaft 8, and consequently shift the
position of the cam 7. This shifting of the cam 7 is effected by the action of
the "governor," when required, as follows:-
In Sheet 2, at Figs. 3 and 5, the connection of the "governor" is shewn with
the above-described apparatus. It will be seen that the lower portion of the
tube or ferule surrounding the " governor" spindle is provided with a pair of
disc or friction pullies 24, 24, so connected as to rise and fall as the
"governor" balls expand or contract by the variation of their velocity; these
friction pullies are made to act on a face plate or disc, 25, fixed either at the
end of the shaft 23, or a cross shaft connected with it; these friction pullies,
24, are so arranged that when the engine is at its proper speed they shall not
be in contact with the friction plate 25, but when the balls of the "governor"
expand by any increase of speed, the lower friction pulley will be raised so as
to act on the face plate, and cause it to revolve in a certain direction, and in
the contrary direction when they fall below the proper velocity, so as to cause
the
upper friction pulley to act on the opposite point on the surface of the face
plate.
The shaft 23 must be connected with the worm 22, in the bottom of
the headstock; the manner of connection will vary according to the difference
of situation. In some cases it may be connected direct, in others it may require
to be conveyed by small shafts and bevil or mitre wheels, which must be so
arranged as to put the cam forward, that is, to cause the steam to be cut off
sooner when the speed of the engine is too quick, and the contrary when too
slow.
In Sheet 3, Figs. 1, 2, and 3 represent plan, end, and side views of a modi-
fication of apparatus designed to effect the same purpose. a, a, represents a head-
stock mounted on a slide, and worked in a similar manner to the one last
described; the shaft 6 is also driven in the same manner by a shaft proceeding
from the fly-wheel shaft, as shown in Fig. 3, Sheet 2. The "cutting off"
cam f is also mounted on the shaft b, and acts against the friction bowl g,
placed at the end of the rod 6, in connection with the "cutting off" slides.
The bevil wheel C has a key in its boss which enters a straight groove d,
formed in the shaft b, and allows the said shaft b to move backwards or for-
wards in the direction of its length, at the same time that it communicates a
rotary motion to it the same as that of the fly-wheel shaft. On another portion
of the shaft 6 there is a groove l, cut in a helical form, so as to make about a
quarter of a turn of the worm in about 8 inches length. In the boss of the
cutting off"
cam f there is also a fast key, which slides in this inclined
groove l, and which connects the cam with the shaft.
the position of the cam f. on the shaft b, and thus
46
The method of altering
"cutting off" the steam

page_text: sooner or later is by sliding the shaft 6 through the bosses of both the wheel C
and the cam f, which by reason of the key in the boss of the wheel C sliding
in a straight groove, and that of the cam f in an helical one, they are shifted
with respect to each other more or less. The shaft is shifted for this
purpose, and held as required by two levers 9, 9, engaged by means of a
swivelling nut and screw h, and a small pair of mitre wheels i, i, with the
shaft 23, proceeding from the "governor," which shaft in the former arrange-
ment was engaged with the worm and wheel 22 and 21. It will also be
evident that in this arrangement of the apparatus the connection of the sliding
headstock with the common eccentric rod t, may be made as above shewn, or
may be slightly varied. In the former arrangement it is in fast connection
with it, and in the present they are merely connected by the shaft 6 passing
loosely through a bush or bearing u in the eccentric rod.
Another arrangement of apparatus for connecting the "cutting off" cam
with the governor is shewn in elevation at Fig. 4, and plan view, Fig. 5, in
Sheet 3. a, a, represents a fly-wheel shaft, on which the common eccentric b
is fixed, as before described. c is the "cutting off" cam, and shewn in section,
Fig. 4, and partly in section in Fig. 5. d is friction band hinged at e. f is a
bolt passing through the "cutting off" cam, and between the ends of the fric-
tion band; this bolt is to act as a driver or connection between the friction
band and the "cutting off" cam. g is a pinion with a flange, on which are
certain projecting pins or studs z, z; this pinion is fixed on the pin h, which
revolves when acted on in a hole bored through the eccentric 6, and is geared in
an internal wheel y attached to the "cutting off" cam. In this arrangement the
cam is connected to the excentric by the friction of the band d, which friction
may be adjusted by tightening the bolt i (Fig. 5), for which purpose a hole is
at k, must be left either in the periphery or the side of the cam to admit a
screw key; a helical spring 7 under the head of the bolt i will keep the friction
equable; this friction band must be so tight as to overcome the resistance of
working the "cutting off" slide, but not so tight as to cause any unnecessary
strain upon the machinery connected with it. The manner in which the
"cutting off" cam may be moved forward or backward by the action of the
"governor may be much varied. The following is one method:-m is a
standard, the top of which is formed into a stud, on which is mounted a piece
of metal, of which two views are shewn at n, n; this piece of metal has an arm
projecting from the centre, which is connected to the "governor" in such a
manner that if the balls expand it will be pulled in one direction, as 1, 2, and
if they collapse it will be pulled in another direction, as 1, 3, and when they
are at a proper state it will have to assume a middle position, as 1, 4. When

page_text: the above-mentioned arm is pulled in the direction 1, 2, it is evident that the
projecting piece o will be protruded, so that the studs z, z, will have to strike
against it at every revolution of the fly wheel shaft, and that when this is the
case, and the fly-wheel shaft is revolving in the direction of the arrow at 7, the
pinion will be moved, each successive revolution of the fly-wheel shaft, in the
direction of the arrow marked ", which, being geared in the teeth attached to
the cam, will turn it in a corresponding direction. When the above-mentioned
arm is pulled in the direction 1, 3, it is evident that the motion produced on
the pinion and cam will be in the opposite direction; and when in the position
1, 4, it will have no action on the pinion and consequently none on the cam.
This may be effected by the "governor" as follows:- is a governor spindle.
the expanding and collapsing of the balls cause the ferrule or bush to rise and
fall, on which are the friction pullies 2, 2, (as before). u is a face plate, plain
or nearly so, on the face, except at certain places, 5, 6, where the face is hol-
lowed out, so that when either of the hollows come opposite either of the
friction pulleys v, its action will cease. The friction pulley v is represented in
the Drawing, is opposite the hollow 6; while this is the case, the pulley v
cannot act on the face plate, and the crank pin on the same shaft as the face
plate u will hold the rod s, as shewn; this will cause the "cutting off" cam c
to be gradually shifted, as before shewn, which will alter the speed of the
engine. If the friction pulley should now come into contact with the face
plate, it would turn it until the hollow 5 come opposite, at which time the
weight A would be perpendicular over the centre of the crank pin t, the stop o
would be withdrawn, and further action on the cam would cease; but should
the balls continue to collapse, the friction pulley will act on the face plate
after it has traversed across the hollow 5, and cause the lever to assume the
position marked 1, 3.
Having now described the nature of my said Invention, and the manner of
carrying the same into practical effect, I desire to be distinctly understood that
I claim,
Firstly, the peculiar method of "cutting off" the steam in steam engines
when worked expansively, by the application and employment of the "cutting
off" plates placed in the inside of the common p, or slide valve, as exhibited
in the Drawings attached, and herein particularly set forth.
Secondly, I claim the application and employment of a cam or tappet, which
is moveable round its axis. for the purpose of altering the time of "cutting off"
the steam, and which is capable of being so moved either by hand or mechanism,
whilst the engine is at work; and
Thirdly, the methods of moving the said cam round its axis for the said

page_text: purpose by the action of the "governor," as also exhibited in the Drawings
attached and above particularly described.
In witness whereof, I, the said James Petrie, have hereunto set my hand
and seal, this Twenty-first day of November, One thousand eight
hundred and forty-four.