IMPROVEMENTS IN SLIDE VALVES FOR STEAM ENGINES
Year: 1854

page_text: LETTERS PATENT to William McNaught, of Rochdale, in the County of
Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN SLIDE VALVES
FOR STEAM ENGINES."
Sealed the 30th March 1855, and dated the 3rd October 1854.
PROVISIONAL SPECIFICATION left by the said William McNaught at the
Office of the Commissioners of Patents, with his Petition, on the
3rd October 1854.
I, WILLIAM MCNAUGHT, of Rochdale, in the County of Lancaster, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN SLIDE
VALVES FOR STEAM ENGINES" to be as follows:-
My Invention refers to valves for engines in which it is desired to cut off
the steam when a portion of the stroke has been performed. The valve is so
constructed and arranged as to slide in the ordinary manner during the time
that steam is to be admitted; but when it is desired that the supply shall cease,
motion in another direction is imparted to the valve, by which the passages are
closed. In order to illustrate my Invention, I will mention a particular arrange-
ment I employ instead of forming the induction passages as usual, I con-
struct them with alternate openings and closed parts, and in like manner form
the extremities of the valve during the ordinary sliding motion; the openings
in the two parts are coincident, and steam will therefore flow through them
into the working cylinder; but at that period when it is desired to cut off the
supply, I impart a transverse motion to the valve, by which means the solid
parts thereof will pass over the alternate openings which constitute the steam
passages. A method I adopt for effecting the two motions is as follows:-Upon
1

page_text: the slide valve rod is fixed a projection, which extends into a groove, so as to
carry the valve to and fro during the ordinary motion; upon the rod, however,
being turned upon its centre, by any suitable connection with the engine, the
said projection operates as a cam, upon the recess in which it is placed, and
causes the required transverse movement of the valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William McNaught in the Great Seal Patent Office on the
3rd April 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MENAUGHT, of Rochdale, in the County of Lancaster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Third day of October, 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 William McNaught, Her especial licence that I, the said William
McNaught, my executors, administrators, and assigns, or such others as I, the
said William McNaught, 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 "Im-
PROVEMENTS IN SLIDE VALVES FOR STEAM ENGINES," upon the condition
(amongst others) that I, the said William McNaught, 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 William McNaught, 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 state-
ment and accompanying Drawings, that is to say:-
My Invention refers to valves for engines in which it is desired to cut off*
the steam when a portion of the stroke has been performed. The valve is so
constructed and arranged as to slide in the ordinary manner during the time
that steam is to be admitted to the cylinder; but when it is desired that the

page_text: supply shall cease, motion in another direction is imparted to the valve, by
which means the passages are closed.
In order that my Invention may be fully understood, I have appended to
this my Specification a Sheet of Drawings, which I will now proceed to
describe.
Fig. 1 is a plan view of the valve box and valve, the cover being removed;
Fig. 2 is a vertical, and Fig. 3 a cross section, of the same. The lap of the
valve a consists at each end of four projecting portions b, b, b, b, bx, bx, bx, bx,
with intervening spaces c, c, c, c, c*, c*, c*, c*; these projecting portions and
spaces are not opposite to each other, but are so formed that the parts b or b*
are in a line with the spaces on the other side. The apertures leading to the
cylinders are shewn by dots, surrounded by red color at d, d*, and are of similar
form to the laps of the valve, but the spaces and intervening projections are
situate opposite to each other. The valve rod is shewn at e, upon which are
mounted two levers f, projecting into and bearing against the edges of recesses
formed within the valve a. As therefore the valve rod is caused to move to
and fro by any of the usual means adopted for that purpose, the valve will be
moved in the same directions; but if during these movements the rod e be
turned upon its centre, then the levers f will act in the same direction, and
impart a transverse motion to the valve; and it is evident, if this be done when
the laps bor bare between the apertures d or d*, and through which steam is
flowing, that those passages will be closed, and the supply of steam cut off.
The mechanical arrangement for effecting this transverse motion of the valve
may be varied considerably, and will of necessity be modified, in order to meet
particular constructions of engines; but I have in the Drawing, Fig. 1, shewn
an arrangement which will serve for illustration and the better explaining of
my Invention.
Upon the valve rod is mounted fast a lever g, carrying at its
other end a roller, situate within a recess formed by two blocks h, i, the inward
boundaries of which are formed by inclines j, k, as shewn in the Drawing; the
blocks h, i, are capable of being adjusted independently of each other upon
parts which support them, whereby the inclined edges may be caused to advance
towards or recede from each other, and they are capable of being retained in
any
desired position by means of bolts and nuts. According to the position
shewn in the Drawing, the valve is supposed to be moving in the direction of
the black arrow, and the spaces c are advancing over the apertures d, so as to
admit steam to the working cylinder; and this will continue until it is desired
that the supply shall be cut off, by which time the roller of the lever g will
have arrived in contact with the curved incline j, by which means the rod e
will be caused to turn upon its centre, and thro' the medium of the levers f

page_text: communicate a transverse motion to the valve in the direction of the red
arrow; the apertures d will therefore be closed, and the desired operation
obtained. The altered position of the parts above described will have caused
the spaces c* to assume situations coincident with the openings dx, and upon
the return motion of the valve steam will be admitted through them to the
cylinder, during which the roller g will advance along the straight side of the
block until the steam is again to be shut off, when the valve will be returned
to its former position by contact of the roller with the incline k. If it be
desired to alter the periods at which the steam shall be cut off, it will merely
be necessary to adjust the blocks h, i, so that the inclines thereon shall be
further from or nearer to each other. The above is a method by which the
transverse motion of the valve may be effected, but it will be obvious that
rotary cams or other apparatus may, by suitable connections, be arranged to
produce the like result. The vibratory motion of the valve rod e renders it
necessary that its connection with the motive power should be varied from that
in general use; a method I adopt is shewn in Fig. 1. Upon the rod e are
placed two discs 1, 1, formed with collars, which are caused to bear firmly
against each other by means of nuts n; between these discs is placed the cross
head o, which is connected to the excentric or other ordinary apparatus; by
these means, the necessary slide motion is given to the valve, the rod of which
is at the same time at liberty to turn upon its centre, carrying with it the
discs 1, 1.
Having thus described and ascertained the nature of my said Invention, and
the manner in which the same is to be performed, I desire it to be understood
that I claim, as secured to me under the above in part recited Letters Patent,
imparting to the slide valves of steam engines an additional motion, whereby
the steam passages leading to the cylinders are closed at required periods
of the stroke.
In witness whereof, I, the said William McNaught, have hereunto set my
hand and seal, this Second day of April, in the year of our Lord
One thousand eight hundred and fifty-five.
WMNAUGHT. (L.S.)