CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1848

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 Tenth day of April, in the eleventh year of Her reign, and in
the year of our Lord One thousand eight hundred and forty-eight, did, for
Herself, Her heirs and successors, give and grant unto me, the said James
Petrie, Her especial licence, 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, 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 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 recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.

page_text: 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
ascertained in and by the Drawings hereto annexed, and the following
explanation thereof (that is to say):-
My Invention of Certain. Improvements in Steam Engines consists principally
in certain additions to or improvements upon a former Invention, for which
Her Majesty's Royal Letters Patent were granted to me, bearing date at West-
minster, the Twenty-second day of May in the seventh year of Her reign, the
Specification of which was duly enrolled in Chancery. It will be seen, by refer-
ring to the Specification of my former Patent, that my Invention consisted,-
Firstly, 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.
And, secondly, 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.
My present, Invention consists,-
Firstly, in the method of connecting the said "cut-off slides" to other
working parts of the apparatus.
i .
Secondly, in the peculiar arrangement of mechanism employed to produce
the requisite motion of the "cut-off slides."
"
Thirdly, my improvements consist in the method of. connecting the
governor" with the differential apparatus, so as to set the "cut-off cam
either earlier or later by the action of the governor.
And, fourthly, in certain arrangements of mechanism, for the purpose of
indicating at what point of the stroke of the engine the steam is cut off, and
for altering the same either sooner or later by hand, as may be required.
Having now described the nature of my said Invention, I will proceed to
describe the mode of carrying the same into practical effect. And in order that
my Invention may be readily understood, I have attached to these Presents two
Sheets of Drawings representing my several improvements, and have marked
the same with figures and letters of reference corresponding with those in the
following description thereof; and in order more distinctly to point out the
new or improved part of the mechanism, they are represented as shaded with
color; the ordinary parts and those described in the previous Patent, in con-
nection therewith, being drawn in outline only.

page_text: In Sheet 1, Fig. 1 is a side elevation of the cylinder of a steam engine,
shewing the valve boxes and valves in section; and Figure 2 is a front view of
the side pipes and valve boxes of a steam engine, a portion of the front of the
valve boxes being removed, and the valves shewn in section. A, A, is the steam
cylinder; B, B, is the D or slide valves; and C, C, are the "cutting-off slides."
These slides are connected to the other working parts hereafter mentioned in
the following manner:-The ordinary spindle or rod used for working the D
valves is now made hollow, as shewn at a, a, and through this the spindle b; b,
which is connected to the "cut-off slides" passes, being attached at the lower
end to a sliding stuffing box or "boot," working or sliding on the hollow valve
rod a, a. The D valves are attached to the hollow rods a, a, by cross bars
and rods c, c. It is obvious that where required, as in marine or other
engines, the cutting-off slides" may be worked from the top end of the side
pipes or valve casing. d, d, is the cross shaft for working the D or slide
valves (see also Fig. 3, which is a plan view of the cross shaft) between the
arms e, e, of which there is a centre or fulcrumf, upon which a lever g, g²,
vibrates. This lever g is so constructed and arranged that one end thereof
nearly coincides with the centre of motion of the shaft d, and the other end with
the ends of the arms è, e, whilst the fulcrum fis betwixt the two. Now it will
be evident that upon motion being communicated to the cross shaft d by
means of the lever and excentric rod i as usual, as long as the end g of the
said lever is held in the centre of motion of the cross shaft d, d, the other end
g' of the said lever will have the same movement as the ends of the arms e, e,
of the cross shaft; and the said cross shaft being attached by the links and cross
bar k, k, to the hollow valve rod a, a, and the end of the lever g, g², to the cut-
off' slide rod b, b, then the valves B, B, and "cut-off" slides C, C, will have the
same motion, that is, the "cut-off" slide will remain stationary in the interior of
the D valve; but if the end'g of the said lever be now raised or depressed above
or below the centre of the cross shaft, the "cut-off" slides C, C, will have a
corresponding change of position in the interior of the D valves, so as to
cover or uncover the sluice through which the steam passes, and they will
retain that relative position as long as the end of the lever g remains raised or
depressed above
below the centre of motion of the shaft d. By this means
the 'head stock carrying the differential motion may now remain stationary,
instead of sliding backwards and forwards, as described in the previous Patent.
Another mode in which this may be effected is as follows: instead of the
lever'g, 9, vibrating on a fulcrum between the arms of the cross shaft, it
might vibrate on a fulcrum suspended from the arms of the cross shaft; or

page_text: this compound motion of the "cut-off slides" may be effected without any
modification of the cross shaft, which works the D valves by an arrangement
of mechanism similar to either of the before-mentioned modes, placed in any
convenient situation, and connecting the same with the cam and the "cut-off
slides."
46
"
The third and fourth parts of my Invention are seen best in Sheet 2 of the
Drawings, in which Fig. 1 is a plan view of part of the crank, shaft, excentric,
and rod of a steam engine, with the differential apparatus applied thereto,
shewing a method of driving the cam; and Fig. 2 an elevation of the same,
shewing a method of connecting the differential apparatus to the "governor;'
and also a method of indicating the point of the stroke at which the steam is
cut off, and an arrangement for setting the cutting-off cam sooner or later by
hand, as required. The "governor" spindle is made tubular, as usual, and
in the interior is a rod connected to the sliding ferrule m by a cotter, the
other end of which rod raises or lowers a driver n, which passes through a
slot in the hollow spindle l. This slot is situated between two bevil wheels
o, o, the faces of which are furnished with projecting pins p, p², the said
wheels o, o', being loose upon the spindle 1. Both of these bevil wheels o, 0¹,
are in gear with a third bevil wheel q, consequently, when the balls r, r, of the
governor" expand, the driver n is raised, and comes in contact with the two
projecting pieces p', p', in the face of the upper bevil wheel o, and thus turns
the wheel 9 in a certain direction. When the balls r, r, collapse, the driver
n comes into contact with the pins p, p, in the face of the lower bevil wheel o,
and thus turns the wheel q in the opposite direction. The bevil wheel q is
connected by friction to the stud *, which, by means of the change wheels
8, 8, and bevil wheels t, t', drives the upright shaft u, upon which the worm vis
keyed. The worm v takes into the teeth of the quadrant w, and thus sets the
cam earlier or later. The change wheels s, s, are employed in order to give
the most suitable relative speed of the "governor" spindle round the worm or
quadrant w, as it will be found in practice that in some cases the cam is
required to change quicker than for others, to ensure regularity in the speed of
the engine. When it is required to alter the position of the cam by hand,
the bevil wheel t' at the upper end of the vertical shaft u must be lifted out
of gear with the bevil wheel t, thus breaking the connection between the worm
shaft u and the "governor," so that the said shaft can be turned round by hand,
and by this means the position of the "cutting-off" cam a can at any time be
altered by hand to any situation required. And in order that it may always be
known at what part of the stroko of the engine the steam will be cut off

page_text: purpose.
This
there is a nut upon the upright shaft u, which is screwed for the
nut rises or falls as the cam may be put backwards or forwards, to which nut
is attached a pointer or finger y (the position of which, upon the index plate z,
(on which is a scale representing the stroke divided into fractional parts), indi->
cates the point of the stroke of the engine at which the steam is cut off. The
proprietor or the engineer can thus at any time ascertain by inspection whether
the steam is being cut off as early as it ought to be. The worm wheel w
requires teeth upon a portion only of its periphery, so as to allow of its making
a fourth of a revolution, as it is evident, from the nature of the differential
apparatus, that one fourth of a revolution of the worm wheel w causes one
half a revolution of the cam r, and that this comprises the whole stroke of
the engine. The reason why the bevil wheel q is connected to its stud by fric-
tion, as before mentioned, is, that it may revolve on its axis should the worm
wheel w be turned by the "governor" to the end of the toothed part of its
periphery. The construction of the differential apparatus is also improved.
The bevil wheels 1 and 2 are both placed loose upon the shaft, and are fur-
nished with long bosses, upon one of which the cam x is fixed, and upon
the
other is keyed a spur wheel 3, which is driven by a similar wheel 4, keyed
upon the crank shaft D of the engine; also the worm wheel w is furnished
with two planet pinions 5, 5, and is keyed fast on the shaft. The differential
apparatus may be driven by spur or bevil geer from the crank shaft or other
shaft. I may also remark, that a lever with a swivelling nut at the end may.
be employed instead of a worm quadrant.
Having now described the nature and object of my said improvements,
together with the manner of carrying the same into practical operation, I
would remark, in conclusion, that I claim as my Invention,-
First, the peculiar method of connecting and working the cutting-off
slides.
Secondly, the method of varying the position of the "cut-off" cam by means
of the "governor;" and,
Lastly, the arrangement of mechanism for indicating and shewing at what
point of the stroke of the engine the steam is cut off, and the method of setting
or adjusting the same, either earlier or later, by hand, as may be required.
In witness whereof, I, the said James Petrie, have hereunto set
my hand and seal, this Ninth day of October, One thousand eight
night
-
JAMES (L.S.) PETRIE.

page_text: AND BE IT REMEMBERED, that on the Ninth day of October, in the
Twelfth year of the reign of Her Majesty Queen Victoria, the said James Petrio
came before our said Lady the Queen in Her Chancery, and acknowledged
the Instrument aforesaid; and all and everything: therein contained and
specified in form above: written; and also the Instrument aforesaid was
stamped according to the tenor of the Statute made in the fifty-fifth year of
the reign of His late Majesty King George the Third.
**Inrolled the "Tenth day of October, One thousand "eight" hundred and
forty-eight:
7.
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