IMPROVEMENTS IN STEAM. ENGINES
Year: 1870

page_text: LETTERS PATENT to William Scott Underhill, of Newport, in the.
County of Salop, Engineer, for the Invention of "IMPROVEMENTS IN
STEAM. ENGINES."
Sealed the 22nd July 1870, and dated the 25th January 1870.
PROVISIONAL SPECIFICATION left by the said William Scott Underhill
at the Office of the Commissioners of Patents, with his Petition, on
the 25th January 1870.
I, WILLIAM SCOTT UNDERHILL, of Newport, in the County of Salop,
Engineer, do hereby declare the nature of the said Invention for “IM-
PROVEMENTS IN STEAM ENGINES," to be as follows, that is to say:→
My improvements more particularly refer to the relative positions of
the throttle and slide valves, being so placed that full boiler pressure is
admitted into the cylinder. The throttle valves of steam engines are
usually placed a considerable distance from the cylinder, which
arrangement is objectionable, for the steam remaining between the
throttle and the slide valve is always of varying pressure.
"

page_text: The object of my improvements is to overcome these objections.
The steam chest is brought in direct communication with the boiler.
The slide valve and throttle valve are combined; the slide valve is
jacketted, and from the jacket issues a pipe, in which is fitted a throttle
valve of ordinary or other approved form, the slide valve rod answering
the double purpose of throttle and slido rod. The slide rod is supported
at its outer end. by the arm of the governor, to which is attached an
ordinary fork and quadrant, the latter having a D or other other approved
shaped hole in the boss; the end of the valve rod is formed so as to
work freely through it; by these arrangements the governors have instan-
taneous control over the steam as it passes to the cylinder. The valve
rod is fitted with an adjustable collar made in two parts, so that accurate
adjustment can be secured and maintained. I prefer to work this
combination or compound valve by a fork and rocking shaft by which I
am enabled to use one eccentric only to give motion to both pump and
valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Scott Underhill in the Great Seal Patent
Office on the 25th July 1870..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
SCOTT UNDERHILL, of Newport, in the County of Salop, Engineer,
:send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of January, in the
year of our Lord One thousand eight hundred and seventy, in the
thirty-third year of Her reign, did, for Herself, Ier heirs and successors,
give and grant unto me, the said William Scott Underhill, IIer special
licence that I, the said William Scott Underhill, my executors, ad-
ministrators, and assigns, or such others as I, tho said William Scott
Underhill, 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

page_text: Invention for "IMPROVEMENTS IN STEAM ENGINES," upon the condition
(amongst others) that I, the said William Scott Underhill, my exe-
cutors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
samo 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 Scott Underhill, 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, reference being had to the Drawings here-
unto annexed, and to the letters and figures marked thereon, that is to
say :-
My improvements more particularly refer to the relative positions of
the throttle and slide valves, being so placed that full boiler pressure is
admitted into the cylinder. The throttle valves of steam engines are
usually placed a considerable distance from the cylinder, which arrange-
ment is objectionable, for the steam remaining between the throttle and
the slide valve is always of varying pressure.
The object of my improvements is to overcome these objections.
The steam chest is brought in direct communication with the boiler in
the usual manner. The slide valve and throttle valve are combined;
the slide valve is jacketted, and from the jacket issues a pipe, in which
is fitted a throttle valve of ordinary or other approved form, the slide
valve rod answering the double purpose of throttle and slide rod.
The slide rod is supported at its outer end by the arm of the governor,.
to which is attached an ordinary fork and quadrant, the latter having:
a D or other approved shaped hole in the boss; the end of the valve rod
is formed so as to work freely through it, by these arrangements the
governors have instantaneous control over the steam as it passes to the
cylinder. The valve rod is fitted with an adjustable collar made in two.
parts, so that accurate adjustment can be secured and maintained.
I prefer to work this combination or compound valve by a fork and:
rocking shaft, by which I am enabled to use one eccentric only to. give
motion to both pump and valve.

page_text: I will now proceed to describe my Invention more fully in detail by
aid of the accompanying Drawings, and the letters and figures marked
thereon, that is to say :—
Figure 1 is a front elevation, Figure 2 a plan from the top, Figure 3
a sectional plan, and Figure 4 a back elevation of one of my improved
arrangements for combining the slide valve and throttle valve of steam
engines. (a) represents the slide valve formed with an exhaust cavaty
(a) the slide valve (a) is jacketted as at (6) (6¹) being the ports
conducting the steam into the cylinder; from the jacketting (6) issues
a pipe (c) in which is fitted a throttle valvo (d) of ordinary or other
approved form; (e) is the slide valve rod answering the double purpose
of slide and throttle valvo rod. The slide rod (e) is supported at its outer
end (e) by the arm of the governor to which is attached an ordinary
fork and quadrant, the latter having a D or other approved shaped hole
in the boss, and the end of the slide rod (e) is formed to work freely
in such shaped hole, Figure 1 shewing the end (e) of the slide rod (e)
cut upon its under side so as to produco a D form in section; by these
arrangements the governors have instantaneous control over the steam
as it passes to the cylinder. The slide rod (e) is also fitted with an
adjustable collar (f) made in two parts and working upon a screwed
part of the slide rod (e), so that accurate adjustment can be secured and
maintained.
3
Figure 5 represents in sectional plan another form or arrangement of
my improved combination or compound valve. In this case (9) and (h)
are a slide and throttle valve combined; (i) is a jacketting enclosing the
pipe (k) of the throttle (/); the combined valves (9) and h) with the
jacketting (i) slide by means of the slide rod (m) upon a pipe (n)
secured to a fixed annular chamber (o), the slido rod (m) is formed in a
'similar manner to the slide rod (e), Figure 1; (p) is a second slide valve
formed with ports (¹) and working by means of the slide rod (r)
which is actuated by an eccentric and rod not shewn by the arrangment
illustrated in Figure 5. I am enabled to use the combined slide and
throttle valve as a cut-off valve, thus gaining tho advantages of variable
expansion by the use of two valves, and also great governing power by
the nearness of the throttle to the cylinder. I am also enabled to
conduct the steam into and through the jacketting (i) and valves
(g and h) into the cylinder without the steam passing into the steam

page_text: chest in the usual way, by which means the steam in the cylinder. will
be hotter than if it emptied into the ample steam chest first; the steam
chest may therefore only form a jacket for the valves. I prefer to work
my combination or compound valves as described by a fork and rocking
shaft, by which means I am enabled to use one eccentric only to give
motion to both pump and valve.
Having thus described the object and nature of my said Invention,
and the manner in which the same is to be carried into effect, I claim
without limiting myself to these precise details, the several improve-
ments in the arrangement or combination of steam engine valves,
substantially in manner as herein more fully set forth and specified.
In witness whereof, I, the said William Scott Underhill, have
hereunto set my hand and seal, this Twenty-third day of July,
in the year of our Lord One thousand eight hundred and seventy.