CERTAIN IMPROVEMENTS IN LOCOMOTIVE ENGINES, PARTS OF WHICH ARE APPLICABLE TO OTHER STEAM ENGINES
Year: 1843

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ROBERT
HAWTHORN and WILLIAM HAWTHORN, of the Town of Newcastle-upon-Tyne,
in the County of the same Place, Civil Engineers, 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 Seventh day of April, in the sixth year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto us, the said Robert
Hawthorn and William Hawthorn, our exors, admors, and assigns, Her especial
licence, full power, sole privilege and authority, that we, the said Robert
Hawthorn and William Hawthorn, our exors, admors, and assigns, and such
others as we, the said Robert Hawthorn and William Hawthorn, our exors,
adñiors, or assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term of years therein expressed,
Should and lawfully might make, use, exercise, and vend, within that part of
Her Majesty's United Kingdom of Great Britain and Ireland called England,
Her Dominion of Wales, and the Town of Berwick-upon-Tweed, and also in
all Her said Majesty's Colonies and Plantations abroad, our Invention of
"CERTAIN IMPROVEMENTS IN LOCOMOTIVE ENGINES, PARTS OF WHICH ARE APPLICABLE
TO OTHER STEAM ENGINES;" in which said Letters Patent there is contained
a proviso, that we, the said Robert Hawthorn and William Hawthorn, or one
of us, shall cause a particular description of the nature of our said Invention,
and in what manner the same is to be performed; under our hands and seals,

page_text: or under the hand and seal of one of us, to be inrolled in Her said Majesty'
High Court of Chancery within six calendar months next and immediatel
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, we, the said
Robert Hawthorn and William Hawthorn, do hereby declare that the nature
of our said Invention, and the manner in which the same is to be performed
is particularly described..and ascertained in and by the following Specifica
tion thereof, reference being had to the Drawings hereunto annexed (tha
is to say)-
Whereas steam has been heretofore worked expansively in locomotive as
well as other steam engines, but in the case of the former with comparatively
small advantage; for though by varying the stroke of the slide valve the steam
is cut off at various portions of..the stroke. of the piston, yet at the same time
the passages for the ingress and egress of the steam are constantly being
changed, so that little or no benefit results from this mode of expansion:
And whereas also there is great difficulty experienced in keeping the slide
valve steam-tight, or in what may be called a perfect working condition, in
consequence of the constant variation in the stroke, which tends to wear the
surface or face on which it works irregularly: Now, the nature of our said
Invention consists in adapting to locomotive engines an auxiliary expansion
slide frame, which fits to and works upon the same surface or face, and is
actuated by the same eccentrics as the ordinary slide valve, whereby the said
defects arising from the variation in stroke are fully remedied. The slide
valve is kept constantly steam-tight, and rendered regular and uniform in
its action, and the steam may be applied with full and unimpared force untill
cut off, and may be cut off almost instantaneously at any portion of the stroke
of, the piston.
In Figure 1 of the Drawings hereunto annexed we have given an elevation,
partly in section, of so much of a locomotive engine of our construction as is
necessary to exhibit the said improvements; Figure 2 is a plan of a portion of
the gearing, on an enlarged scale; Figure 3 is a plan of a cylinder and steam
chest, with the cover of the steam chest removed, to shew the slide valve and
auxiliary, expansion slide frame; Figure 4 is a side view of one cylinder and
longitudinal section of the slides and steam chest; and Figure 5, a cross section
of the parts represented in Figure 4. The cylinders, it will be observed, are
placed on the outside. a represents the ordinary slide valve, which is placed
in a horizontal position, and worked directly from the driving axle A by two
ordinary eccentrics 1 and 2. B is a coupling link, of a new form, which is

page_text: contrived so as to diminish as, much as possible the friction and wear upon the
slotted ends of the eccentric rods 3, 4, and the connecting. pin; the wide space
in the middle part of the link allows the eccentric rods to work without moving
the slide valve, so that the valve is constantly at rest, and closely shut when
out of gear. c, c, is the new auxiliary. expansion..slide frame, which, as before
stated, is fitted to and works upon the same surface or face, as the slide, valves.
d, d, (Figure 4,) are projections on the inside of the expansion slide frame, so
that when the frame is in motion it overlaps alternately the ends of the slide
valve in a greater or less degree; according to the amount of the expansion..
e is a hollow rod, attached to the expansion slide frame in the usual manner,
and made hollow, in order that the rod (5) to the ordinary, slide valve, may pass
through it; (it may be made also solid, similar to that of the slide valve, and
worked through a separate stuffing; box either above or at one side of the slide
rod.) (Figure 1) is a fixed pivot or short. weigh bar., g, h, (Figure 1,) a
beam on two levers, shewn separately in Figure 6, worked or fixed upon the
said pivot or short weigh bar, as the case may be; the lower end of the beam
or lever h is connected by the links i and the rod e to the expansion slide
frame, and the upper end of the beam or lever g is connected by the rod E to
the back eccentric, or that for working the engine the back way, so that by the
gearing thus described the said eccentric communicates its motion to the
expansion slide frame. k, Figures (1 and 6) represents' a groove or slot in
which the pin at the end of the rod E moves; and o, 1, 1, 1, (Figure 1,) gear-
ing by which the engine driver can vary the position of this pin at pleasure,
and thereby cause the stroke of the expansion slide frame to correspond
exactly with the amount of the expansion required. A dial is placed at the foot
plate in view of the engine driver, which indicates minutely the amount of the
expansion at any part of the stroke. When expansion is not required, the pin
is raised into the slit m (Figure 6), and at the same time the inclined surfaces
on the end of the lever o press against the pins 6, 7, which keep the expansion
slide frame firmly secured and at rest when out of gear, and thereby prevent
all unnecessary wear and tear.
The movement thus communicated by the back eccentrics to the expansion
slide frame has a very advantageous effect as regards cutting off the steam
quickly. A similar movement may also be obtained by different gearing where
only one eccentric is used to one cylinder, by connecting the said gearing to
one side of the eccentric at a certain angle with the eccentric rod, but we
prefer using two eccentrics. When the slide valve has been once adjusted to
work in the manner before described, it never has occasion to be varied, what-
ever may be the amount of the expansion. We find it to be of very consider-

page_text: _able advantage to regulate the blast pipe and damper, so that they shall act
with more or less energy, according to the amount of expansion required,
which is regulated at the discretion of the engine driver from the foot plate.
And having now described the nature of our said Invention, and in what
manner the same is to be performed, we declare that what we claim is,--
First, the auxiliary expansion slide frame before described, fitted to and
working as aforesaid, upon the same surface or face as the ordinary slide
valve.
And, secondly, the method or means before described of communicating
motion to the said auxiliary expansion slide frame from the ordinary eccentrics
used for working the slide valves, whether one eccentric is made use of or two
eccentrics, and whether such method or means are applied to the auxiliary
expansion slide frame of our Invention before described, or to any other
appendage intended to serve the same purpose..
In witness whereof, we have hereunto set our hands and seals, this
Thirtieth day of August, One thousand eight hundred and forty-three.