AN IMPROVED REGULATOR FOR STEAM ENGINES
Year: 1872

page_text: LETTERS PATENT to Alfred Henry Davies, of Rhymney Iron Works,
in the Parish of Bedwellty, County of Monmouth, Engineer, for
the Invention of "AN IMPROVED REGULATOR FOR STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said Alfred Henry Davies
at the Office of the Commissioners of Patents, with his Petition,
on the 29th November 1872.
I, ALFRED HENRY DAVIES, of Rhymney Iron Works, in the Parish
of Bedwellty, County of Monmouth, Engineer, do hereby declare the
nature of the said Invention for "AN IMPROVED REGULATOR FOR STEAM
ENGINES," to be as follows:-
This Invention is designed to enable steam engines worked by means
of slide valves to be worked expansively to any degree without prac-
tically altering what is technically called the "lead" of the valve, and
also to enable the same engines to work in the reverse direction (with
the same advantage as to "lead") with only one eccentric cam.

page_text: In order to carry out this Invention the eccentric cam instead of
being keyed or bolted to the crank shaft in the usual manner is loose
and capable of being turned round on the shaft, and at the same time
(by means of an enlongated slot in the cam) of being moved radially to
the centre of the shaft so that it may be brought more nearly concentric
with the shaft. At the side of the loose eccentric cam on the same
shaft is placed a cam plate or crank keyed or bolted to the shaft in the
ordinary manner. To this cam plate or crank the loose eccentric is
fastened by a bolt or pin passing through a hole provided in either the
cam plate or the loose eccentric, and also through a peculiar curved slot
which may be made either in the cam plate or the loose eccentric cam.
This slot is made of such a curve that while allowing the loose eccen-
tric cam to be turned round on the shaft at the same time shortens its
stroke by compelling its centre to move radially towards the centre of
the shaft (by means of the elongated slot), but keeping it always at the
same distance from a line at right angles to the line passing through the
crank pin and the centre of the shaft.
The continuous curved slot here described is not a necessity. A series
of holes the centres of which are placed on the centre line of the slot
may be used instead.
When the loose eccentric cam has been turned until its centre is on
the same line as the centre of the crank pin (and on the opposite side
of the centre of the shaft), it will give its shortest throw, and will then
cause the valve to travel only a distance necessary to give the required
lead" (or opening of the steam ports) for each end of the cylinder.
By continuing the curved slot beyond the centre line of the crank
and turning the loose eccentric cam still farther round the engine will
be enabled to work in the reverse direction, and with the same advantage
with regard to the "lead."
By varying the position of the fastening bolt or pin in the curved
slot the valve may be made to "cut off" at any required part of the
stroke, and thus work the steam to any required degree of expansion.
The eccentric cam may be embraced by a clip and connected to the
valve in any ordinary manner.

page_text: SPECIFICATION filed in pursuance of the conditions of the Letters
Patent, and of an Order of the Lord Chancellor by the said Alfred
Henry Davies in the Great Seal Patent Office on the 9th June 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
HENRY DAVIES, of Rhymney Iron Works, in the Parish of Bedwellty,
County of Monmouth, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-ninth day of November, in the
year of our Lord One thousand eight hundred and seventy-two, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and succes-
sors, give and grant unto me, the said Alfred Henry Davies, Her
special licence that I, the said Alfred Henry Davies, my executors,
administrators, and assigns, or such others as I, the said Alfred
Henry Davies, 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 IMPROVED REGULATOR FOR STEAM ENGINES," upon the con-
dition (amongst others) that I, the said Alfred Henry Davies, my
executors 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 same was to be performed, and cause the same to be filed in the
Great Seal Patent Office on on before the Ninth day of June, (A. H. D.)
One thousand eight hundred and seventy-three.
NOW KNOW YE, that I, the said Alfred Henry Davies, 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 in writing, and on reference to the accom-
panying Sheet of Drawings, that is to say :—
This Invention is designed to enable steam engines worked by means
of slide valves to be worked expansively to any degree without prac-
tically altering what is technically called the "lead" of the valve, and
also to enable the same engines to work in the reverse direction (with
the same advantage as to "lead") with only one eccentric cam.

page_text: In order to carry out this Invention, the eccentric cam instead of
being keyed or bolted to the crank shaft in the usual manner is loose
and capable of being turned round on the shaft, and at the same time
(by means of an elongated slot in the cam) of being moved radially to
the centre of the shaft so that it may be brought more nearly concentric
with the shaft. At the side of the loose eccentric cam on the same
shaft is placed a cam plate or crank keyed or bolted to the shaft in the
ordinary manner. To this cam plate or crank the loose eccentric is
fastened by a bolt or pin passing through a hole provided in either the
cam plate or the loose eccentric cam, and also through a peculiar curved
slot which may be made either in the cam plate or in the loose eccentric
cam. This slot is made of such a curve that while allowing the loose
eccentric cam to be turned round on the shaft at the same time shortens
its stroke by compelling its centre to move radially towards the centre of
the shaft (by means of the elongated slot), but keeping it always at the
same distance from a line at right angles to the line passing through the
crank pin and the centre of the shaft.
The continuous curved slot here described is not a necessity. A series
of holes, the centres of which are placed on the centre line of the slot
may be used instead.
When the loose eccentric cam has been turned round until its centre is
on the same line as the centre of the crank pin (and on the opposite side
of the centre of the shaft), it will give its shortest throw, and will then
cause the valve to travel only a distance necessary to give the required
"lead" (or opening of the steam ports) for each end of the cylinder.
65
By continuing the curved slot beyond the centre line of the crank and
turning the loose eccentric cam still farther round, the engine will be
enabled to work in the reverse direction, and with the same advantage
with regard to the "lead."
By varying the position of the fastening bolt or pin in the curved
slot the valve may be made to "cut off" at any required part of the
stroke, and thus work the steam to any required degree of expansion.
The eccentric cam may be embraced by a clip and connected to the
valve in any ordinary manner.
Such being the nature and object of my said Invention for "An
Improved Regulator for Steam Engines," I will now proceed to describe
more in detail the manner in which the same is to be or may be per-

page_text: formed or carried into practical effect, and in order that the same may be
distinctly understood I have annexed hereunto a Sheet of Drawings
illustrative thereof, and have marked the same with figures and letters
of reference corresponding with those in the following explanation
thereof, that is to say :-
In the annexed Sheet of Drawings, Figure 1 represents a side eleva-
tion of a stationary horizontal steam engine, and Figure 2 is a plan view
of the same as seen from above, and part of which is drawn in section.
Figure 3 shews an enlarged side elevation and edge view of my im-
proved regulator as arranged on the general views of the horizontal
engine (Figures 1 and 2); Figure 4 shews a modified arrangement of
the same principle.
Figures 5 and 6 are separate and enlarged detailed views of the
movable eccentric and cam plate shewn in Figure 3, and Figures 7 and 8
are similar enlarged detail views of the moveable eccentric and cam plate
shewn in the modified arrangement (Figure 4.)
Figure 9 illustrates a modification of detail which may be made in
practice.
l
CE
In Figures 1 and 2, " a, a," is the bed plate of the engine; "b," the
steam cylinder; c," the piston; "d," the slide valve; "e," the con-
necting rod; "f," the crank pin; "g," the crank shaft, and "h," the
eccentric rod. The eccentric cam 68
i," instead of being keyed or other-
wise fixed to the crank shaft in the usual manner is loose, and may be
turned round on the shaft, and being provided with an elongated slot ","
(see Figures 5 and 8,) instead of the usual circular hole, its eccentricity
may be varied by moving it to and fro in the direction of the centre line
of the longer diameter of the slot. The ends and the shorter diameter of
this elongated are made so as to fit the crank shaft, the longer diameter
being made longer than the shorter one by a distance equal to the width
of one of the steam ports (less the amount of "lead" fixed upon.) At the
side of this loose eccentric cam is keyed or otherwise fixed the cam
plate "k" (shewn in the detached views Figures 3 and 6). This cam
plate must be fixed exactly opposite to the crank pin "f" of the engine
(as shewn in Figures 1 and 3.) It is provided with a curved slot "m, m,"
of a peculiar shape through which the bolt "n" (Figure 3) required to
fix the eccentric cam "i" in any desired position is passed. This
slot "
'm, m," is made of such a curve that by turning the eccentric

page_text: cam
"
"
"" round on the shaft, the bolt " n," guided by the slot "m, m,'
constrains the centre of the eccentric to move along the line " 0, 0,'
which is parallel to the line ". P, p," passing through the centre of the
shaft at right angles to the centre line of the crank, and on the opposite
side of the shaft at a distance equal to the "lap" of the valve, together
with the "lead" from the centre of the shaft. The eccentric in Figures 1
and 3 is shewn fixed so as to give the full stroke of the valve and open
the steam ports to their full extent when the engine is required to move
in the direction of the arrow. To shorten the throw of the valve and so
cause it to "cut off" earlier, the eccentric cam "i" must be moved
round on the shaft when the bolt "n" will move in the curved slot "m"
towards "s," and the centre of throw of the eccentric will move along
the line "o, o," towards the centre line of the cam plate. When the
eccentric cam has been turned so that the bolt "n" is on the centre line
of the cam plate and exactly opposite the crank pin the eccentric will
give its shortest throw and will only cause the valve to open each steam
port a distance equal to the "
lead"
given (which it will be observed is
when the crank is on the "dead" centre, and the piston at the end of
its stroke), so that the engine has then an equal tendency to move in
either direction indifferently; but as this is not desirable in practice, I
prefer, instead of making the slot "m, m," continuous throughout to
leave a rib of metal as 66
8 " in the centre to separate the forward and
backward portions of the slot as well as to stiffen the cam plate at that
point.
"
To reverse the engine the bolt" n must be taken out and the eccen-
tric cam turned round until the bolt can be inserted in the slot "m, m,"
on the opposite side of the central rib "8"; the engine will then work
in the opposite direction to that indicated by the arrow, and the length
of throw of the eccentric may be again varied as before described, the
"lead" of the valve remaining practically the same whatever be the
length of its stroke.
Figure 4 illustrates a modified arrangement of the same principle, and
Figures 7 and 8 are separate and enlarged detailed views of the same.
The curved guiding slot in this arrangement being made in the moveable
eccentric cam (see Figure 8) while the cam plate "k" is replaced by a
small fixed crank (see Figures 4 and 7) keyed exactly opposite to the
crank pin "f" The centre of the eccentric moves along the line "0,0,"
(Figure 4) as in the arrangement (see Figure 3) before describod, but

page_text: the fastening bolt "n" is fixed, and the curved guiding slot is the
reverse to that shewn in the arrangement, Figure 3, the eccentric cam
also requiring to be turned in the opposite direction in order to attain
the same result.
The reversal of the engine is effected by removing the bolt "n" to the
opposite side of the central rib
as already explained with regard to
the first arrangement.
66 "
8
Another modification in the details which may be made in practice is
shewn in Figure 9, in which the continuous curved slot is replaced by
a series of circular holes. The fastening bolt in this arrangement would
have to be taken out each time the grade of expansion was required to
be varied.
The eccentric cam "i, i," is shewn as solid, but it may be made in two
portions and bolted together, or in any ordinary manner. It is embraced
by a clip and may be either connected direct to the valve spindle as
shewn on the Drawing (Figures 1 and 2), or in any other convenient
manner.
Having now described the nature and object of my said Invention for
"An Improved Regulator for Steam Engines," together with the
manner in which the same is to be or may be performed or carried into
practical effect, I would remark in conclusion that I do not confine
myself precisely to the various details as shewn in the annexed Sheet of
Drawings, but I claim substantially as my Invention the novel method
and arrangement of the peculiar curved guiding slots used with and in
connection with the elongated slot for the purpose of varying the grade
of expansion of, or reversing the direction of steam engines, without
practically altering the "lead" of their slide valves, together with the
other advantages herein-before described and illustrated on the annexed
Sheet of Drawings.
In witness whereof, I, the said Alfred Henry Davies, have here-
unto set my hand and seal, this Ninth day of June in the year
of our Lord One thousand eight hundred and seventy-three.
ALFRED HENRY DAVIES. (L.S.)