CERTAIN IMPROVEMENTS IN MACHINERY
Year: 1854

page_text: LETTERS PATENT to Isaac Dodds, of Sheffield, in the County of York,
Engineer, for the Invention of "CERTAIN IMPROVEMENTS IN MACHINERY OR
Sealed the 18th May 1855, and dated the 11th December 1854.
PROVISIONAL SPECIFICATION left by the said Isaac Dodds at the
Office of the Commissioners of Patents, with his Petition, on the
11th December 1854.
I, ISAAC DODDS, of Sheffield, in the County of York, Engineer, do hereby
declare the nature of my said Invention of "CERTAIN IMPROVEMENTS IN MA-
CHINERY OR APPARATUS FOR WORKING THE SLIDE OR STEAM VALVES OF STEAM
ENGINES" to be as follows:-
My improvements in the machinery or apparatus for working the slide
valves or steam valves of steam engines apply more particularly to locomotive,
marine, and stationary steam engines. My Invention consists in performing
such operations by the novel application, employment, or use of a certain
peculiar arrangement of slide motion, instead of the ordinary and well-known
motions called the "link motion" or the "wedge motion," as hitherto em-
ployed. My improved "slide motion" is to be placed upon the upper and
under sides (so called) of the driving or crank shaft of steam engines, which

page_text: sliding motions are designed to move the "excentrics" which work the slide
valves from the forward driving centre to the neutral and back driving centre
or any intermediate centre, so as to enable the engine driver to reverse the
engine or work the engine at any desired power at pleasure.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Isaac Dodds in the Great Seal Patent Office on the
11th June 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ISAAC
DODDS, of Sheffield, in the County of York, Engincer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of December, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Isaac Dodds, Her especial license that I, the said Isaac Dodds, my
executors, administrators, and assigns, or such others as I, the said Isaac
Dodds, 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 "CERTAIN IMPROVEMENTS IN MA-
CHINERY OR APPARATUS FOR WORKING THE SLIDE OR STEAM VALVES OF STEAM
ENGINES," upon the condition (amongst others) that I, the said Isaac Dodds,
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
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Isaac Dodds, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement and accompanying Drawings, that is to say :-
My improvements in machinery or apparatus for working the slide valves
or steam valves of steam engines apply to locomotive, marine, and stationary
steam engines. My Invention consists in performing such operations, whether
for reversing or working the engine expansively, by the novel application,
employment, or use of a certain peculiar arrangement of slide motion, instead

page_text: and "the
is to
of the ordinary and well-known motions called the "link motion
wedge motion," as hitherto employed. My improved "slide motion
be placed upon the upper and under sides (so called) of the driving or crank
shaft of steam engines, which sliding motions are designed to move the
"excentrics" which work the slide valves from the forward driving centre to
the neutral and back driving centre, or any intermediate centre, so as to enable
the engine driver to reverse the engine or work the engine at any desired
power at pleasure. In order that these. improvements may be practically
exhibited in detail and clearly understood, I have attached to these presents a
Sheet of Drawings, exhibiting such parts of steam engines as are necessary to
illustrate the working of my improvements, and in the several Figures of
which they are shewn as adapted thereto, the whole being drawn upon a scale
of half an inch to a foot.
Fig. 1 exhibits a front elevation of the driving axle of a locomotive
passenger" engine, with inside cylinders, and with the application of the
improved valve gear; Fig. 2 is a plan or top view of the same as it would be
seen if the boiler were removed; and Fig. 3 is a side elevation of the apparatus.
Fig. 4 exhibits a front elevation of the driving axle of a locomotive coupled
engine with outside cylinders, also with the application of the improved valve
gear; Fig. 5 is a plan or top view of the same as it would be seen if the
boiler were removed; and Fig. 6 is a side elevation of the apparatus. Fig. 7
exhibits a front view of the application of the improved valve gear to the
driving shaft of a marine engine with bearings inside of the cranks, as arranged
to drive a screw propeller; Fig. 8 is a plan or top view of the same as seen
from above; Fig. 9 is a side elevation of the apparatus; Figs. 10, 11, 12,
represent corresponding views of the same, but adapted to a marine engine
with bearings outside the cranks. It will be observed that in all these several
Figures similar letters of reference are marked upon corresponding parts of
the apparatus. a is the driving axle; b, b, are the eccentric pulleys, made of
wrought iron; c, c, are the eccentric belts or straps; d, d, d, d, are two pairs
of slides, for reversing and working the engine expansively in either fore or
back gear, (and constituting the principal feature of my Invention, formed or
placed upon the driving axle, and made of wrought iron carefully case hardened,
or of any other suitable material; e is a pulley, formed of wrought-iron plates,
to which the slides d, d, are fixed; f is a brass strap with guides for sliding
the pulley e on the driving axle; the main reversing shaft and levers are shewn
at g, being suspended from the boiler in brass bearings, and placed at right
angles over the axle; the slides d, d, are moved by means of the levers h, h,
which have slide blocks attached to them, working in the vertical guides of the

page_text: brass straps f. i is the reversing link; j is the reversing shaft and lever; and
k is the ordinary reversing handle. In reversing the engine, it will be evident
that the most direct method is by pulling the reversing handle from the left
to the right hand, in the direction of the arrow, shewn in Fig. 1, in which the
radial lines, drawn in red, shews the position of the reversing levers when the
engine is reversed. m, m, represent the tails or connecting rods of the eccen-
trics; and n, n, the slide or steam valves, to be operated upon by the motion
as above described; and it will readily be seen by persons conversant with the
steam engine that such slide valves or steam valves may be thus worked (or by
any other suitable arrangement of leverage) from the forward driving centre
to the neutral and back driving centre, or any intermediate centre in the fore
and back gear, so as to enable the driver to reverse the engine, or work the
engine at any desired power at pleasure. I would remark, in conclusion, that
by means of the notches on the quadrant for holding the reversing handle, as
in the ordinary "link motion," the engine may be worked to any degree of
expansion. The same principle, as well as the parallel grooves & guides,
herein-before described, is also applicable to the tightening up of any form
of incline plane employed in the incline expansive & reversing motion for
steam engines.
Having now described the nature of my said Invention, and also clearly
exhibited in the Drawings attached the manner in which the same is to be
performed, by its application to several descriptions of steam engines, I desire
it to be distinctly understood that I claim the peculiar arrangement, application,
and use of this improved slide motion, employed in lieu of the ordinary "link
motion" and "wedge motion," or any other motion employed for the same
purpose, and effected or obtained particularly by the adaptation of the pieces
or parts marked d, d, in the Drawings, to the driving shaft or crank axle of
steam engines, without in any way confining myself to the precise angle of the
said slide pieces, as shewn in the Drawings, nor to any materials of which
the same may be made.
In witness whereof, I, the said Isaac Dodds, have hereunto set my hand
and seal, the Eleventh day of June, in the year of our Lord One
thousand eight hundred and fifty-five.
ISAAC DODDS. (L.S.)