AN IMPROVEMENT IN STEAM ENGINES
Year: 1855

page_text: LETTERS PATENT to Theophilus Wood Bunning, of Newcastle-upon-Tyne,
Engineer, for the Invention of "AN IMPROVEMENT IN STEAM ENGINES."
Sealed the 18th September 1855, and dated the 30th March 1855.
PROVISIONAL SPECIFICATION left by the said Theophilus Wood Bunning
at the Office of the Commissioners of Patents, with his Petition, on the
30th March 1855.
I, THEOPHILUS WOOD BUNNING, of Newcastle-upon-Tyne, Engineer, do
hereby declare the nature of the said Invention for "AN IMPROVEMENT IN STEAM
ENGINES" to be as follows:-
My Invention consists in isolating or shutting off the main or working slide
or valve from both boiler and condenser, and in admitting steam through an
additional valve on either side of the piston as may be required, and this
without the necessity of moving the main slide, whereby, let the engine be
stopped at any portion of its stroke, steam being admitted through the 'addi-
tional valve will cause the piston to perform an up or down stroke or portion
of a stroke, according to the side on which and extent to which it is so
admitted, until the piston reaches the proper position for the main slide to act,
when the communications from the boiler and to the condenser are opened
and the engine continues its work.
I am aware that in some cases an additional valve has been used, and the
main slide has been isolated or moved by hand to the desired position' for
starting in the direction required, but the peculiar feature of this my Invention
consists in starting the engine at any portion of its stroke without the necessity
of the main slide being ever moved by hand.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Theophilus Wood Bunning in the Great Seal Patent Office
on the 27th September 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THEOPIIILUS
WOOD BUNNING, of Newcastle-upon-Tyne, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of March, in the year of our Lord One
thousand eight hundred and fifty-five, in the eighteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Theophilus Wood Bunning, Her special licence, that I, the said Theophilus
Wood Bunning, my executors, administrators, and assigns, or such others as
I, the said Theophilus Wood Bunning, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention for
"AN IMPROVEMENT IN STEAM ENGINES," upon the condition (amongst others)
that I, the said Theophilus Wood Bunning, by an instrument in writing
under my hand and seal, 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 Scal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Theophilus Wood Bunning, 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 thereof, reference being had to the Drawings hereunto
annexed, that is to say:-
My Invention consists in isolating or shutting off the main or working slide
or valve from both boiler and condenser, and in admitting steam through an
additional valve on either side of the piston, as may be required, and this
without the necessity of moving the main slide, whereby, let the engine be
stopped at any portion of its stroke, steam being admitted through the addi-
tional valve will cause the piston to perform an up or down stroke or portion
of a stroke, according to the side on which and extent to which it is so
admitted, until the piston reaches the proper position for the main slide to act,
when the communications from the boiler and condenser are opened and the
engine continues its work.
I am aware that in some cases an additional valve has been used, and the

page_text: main slide has been isolated or moved by hand to the desired position for
starting in the direction required, but the peculiar feature of this my Invention
consists in starting the engine at any portion of its stroke, without the necessity
of the main slide being ever moved by hand.
Figures 1, 2, and 3 of the Drawings hereunto annexed are different views
of a pair of marine engines having my Invention applied thereto. A, A, are
the starting valves applied according to my Invention; B, B, are their steain
pipes; C, C, their eduction pipes; and D, D, are the rods and handles for
working the starting valves; E is the throttle valve; F, F, the eduction throttle
valves; and G, G, are the rods, levers, and handles by which these valves are
worked; H, HI, are the injection handles; and I, I, are the injection valves;
K, K, are the eccentrics and rods fixed direct to the slides. The other parts
of the engines need not be described.
It will be seen that for the entire management and control of the engines
I make use of five handles: first, the throttle valve handle G, which is also
connected with the two eduction throttle valves, whereby the whole may be
opened and shut together, although the levers of the double beat valves, here
used as throttle valves, are so arranged that the eduction valves are full open
whilst the steam valve is only half open, which gives the engineer the oppor-
tunity of regulating the admission of steam to the engine without diminishing
the eduction opening; second, the two injection handles H, H; and, third,
the two starting valve handles D, D. These two starting valves are ordinary
box valves with three ports, similar in all respects to an ordinary locomotive
or marine box slide, only of very much smaller dimensions than those used in
the regular working of the engine, in fact only large enough to first give the
machinery motion in the required direction. These valves likewise serve as
blow-through valves.
The eccentrics, it will be seen, are only two in number, and the rods are
permanently in gear with the slide rods, since to give the engines motion it is
never necessary to move the large slides. The eccentrics are loose on the
shaft, and work on stops arranged for the forward and backward motion of
the engines.
It will be seen, therefore, that by a simple motion of the throttle valve lever
the ordinary slides are completely isolated and shut off from both the condenser
and boiler, and any motion can be given to the piston by moving the small
starting valves A, A, which have their own separate steam and exhaust pipes.
In fact, during difficult navigation the engines can be easily worked by hand
any direction or for any length of time at a slow pace; and it will be like-
wise seen that after the engine has been worked by hand in any
direction by
in

page_text: the small-starting valves A, A, during a certain portion of half a revolution,
according to the lap, lead; and angle at which the main excentrics are arranged
to work, it will when the throttle valves are opened at once be in a condition
to continue working in the same direction without the assistance of the small
valves."
.. The advantages: I anticipate deriving from this arrangement are, first; con-
siderable saving in first cost, the present" link motion, double eccentrics,
eccentric rods and links, together with the way bars, sectors, levers, and other
contrivances for reversing the large valves, being dispensed with, and others
substituted of a less expensive character; second, considerable facility in
handling. engines, especially those of large power; which are by my arrange
ment rendered: as completely under the command of the engineer as those of
the smallest dimensions; and, third, a considerable saving of fuel, especially
in the case of direct-acting screw' engines. This class of engine'works best
when the slides are set so as to cut off at a very small-portion of the stroke;
but with double eccentrics and link motion there is a limit to this, since at
certain positions with a great lap both parts of both cylinders are closed to
the steam; and should the engines be stopped at any of these positions, they
would not readily be again set in motion; whereas with my gear, let the lap
be what it may, the engineer can always insure motion being given to the
piston by using the small valves:
And having now described the nature of my said Invention, and in what
manner the same is to be. performed, I declare that I do" not limit myself to
this arrangement exclusively; but I claim the combination and arrangement
of the parts of steam engines in 'such manner that the main slide shall be
isolated from the boiler and condenser, and the first motion given to the engine'
by means of an additional or starting valve without the necessity of moving
the main slide by hand.
In witness whereof, I, the said Theophilus Wood Bunning, have hereunto
set my hand and seal, this Eighteenth day of September, One thousand
eight hundred and fifty-five.
THEO. W. BUNNING. (L.S.)