IMPROVEMENTS IN STEAM ENGINES
Year: 1876

page_text: LETTERS PATENT to William Dawes, of Kingston Grove, Leeds, in the County
of York, Engineer, for the Invention of "IMPROVEMENTS IN STEAM ENGINES."
18
PROVISIONAL SPECIFICATION left by the said William Dawes at the Office
of the Commissioners of Patents on the 20th May 1876.
WILLIAM DAWES, of Kingston Grove, Leeds, in the County of York, Engineer.
IMPROVEMENTS IN STEAM ENGINES."
The first part of this Invention consists in a simplified and improved governable
expansion gear" applicable to the ordinary three port and other slide valves, and
it may be thus described-
Having constructed my main valve or valves and their rods and eccentric after
the usual or customary manner, and provided the cut-off slide or slides (valves)
upon or in connection with the same and their rods, I cause the crank shaft end
of the "expansion eccentric rod" to travel in a straight line (or in some cases
nearly so) in lieu of the circle it would describe if attached to a second eccentric,
as is customary in the ordinary hand adjusting "oxpansion gears;" this straight
line, path, or travel of the second or "cut-off" eccentric rod end being across the
line of action of the main valve eccentric rod, and this at various and varying
angles, according to the time, earlier or later, in the piston stroke at which the
cut-off is taking place.
The arrangement of mechanical parts or details for producing this straight line
travel may be varied according to circumstances and the kind or size of engine,
but it must be such as will cause the travel to be equal on both sides of a given
point in the line of the main valve action, and also allow of this line crossing this
central point at any required angle as before explained, for instance, when it is
directly across or at right angles to the main valve line of action it constitutes the
earliest possible cut-off, admitting no steam at all to the cylinder; when at an
angle of 45 degrees from this it will cut off at about "quarter stroke," and when
it is parallel with the main valve line of action (unless arranged as is herein-after
explained) it ceases to cut-off at all, and allows the steam to enter both ends of
the cylinder; the intermediate angles or positions of this travel or line of action
(within this 90 degrees) constituting the various times of cutting off, or degrees
or ratios of expansion, these angles being determined and controlled by the governor
by or through any suitable or convenient connection.
In carrying into effect this part of my Invention I prefer generally to take the
action from the main valve eccentric rod at a point as near as is practicable to the

page_text: eccentric and crank shaft, in some cases employing a pair of dovetailed or other
slides similar to a lathe "slide rest" placed vertically, in some cases a pair of
radial arms and connecting link and rod, and in others an internal rack and pinion,
this choice of actions or arrangements for producing the before described straight
line travel depending upon the kind of engine, the desired economy in first cost,
or other circuinstances; but whichever of the before-named methods I employ I
prefer that it should be supported by or attached to the pedestal which carries the
governor, thus securing facility of connection, simplicity, and fewness of parts.
When it is necessary to extend the range of cut-off or expansion beyond the half
of the piston stroke I arrange the time or angles of action of the before explained
parts with respect to the circle (or nearly circle) formed by the main valve eccentric
rod (at the point of connection or attachment) in such a manner as to give the
necessary "lead" which will extend the range, and also increase the rapidity of
" cut-off."
The second part of this Invention consists in an improved method or system of
relieving or lightening the action of the valves upon their working faces, and is to
a certain extent necessary for the perfect and satisfactory action of the first part,
by rendering the work or duty of the governor so light and easy that its control
of the before-named valves, cut-off, and speed of engine shall be prompt and
satisfactory, this I effect by the employment of wheels, rollers, or "reeling levers,"
applied to or in connection with the cut-off plate or valve in lieu of or in contra-
distinction to the main valve as heretofore applied.
It will be evident that whilst it may be unsafe and therefore impracticable to
employ such a system or method of relief to the main slide valve (as previous
attempts have exemplified) its application to the cut-off valve or plate, or any
similar plate upon the main valve, will be safer and more satisfactory.
In carrying into effect this part of my Invention I employ four or any convenient
number of wheels, rollers, or "reeling levers" underneath, that is, for carrying or
supporting the cut-off valve, these wheels, rollers, or reeling levers being attached
to or supported by either the sides of the main valve or by the stationary "valve
scat face," according to circumstances and the extent of relief required, the former
relieving the cut-off valve only, and the latter relieving both valves, without danger
of leakage to the main valve faces, from the fact that there will be at all times
sufficient pressure upon that valve, notwithstanding the relief, to keep it tight
upon its "seat" and face.
When no expansion valve or plate is required I sometimos employ in lieu
thereof a similar perforated plate and wheels, rollers, or reeling levers for relieving
the main valve, the said wheels or rollers not being applied to the main valve, but
to the perforated plate, as herein-before explained.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Dawes in the Great Seal Patent Office on the 18th November
1876.
WILLIAM DAWES, of Kingston Grove, Leeds, in the County of York, Engineer,
"IMPROVEMENTS IN STEAM ENGINES."
The first part of this Invention consists in a simplified and improved governable
"expansion gear" applicable to the ordinary "three port" and other slide valves,
and it may be thus described-
Having constructed my main valve or valves and their rods and eccentric after
the usual or customary manner, and provided the cut-off slide or slides (valves)
upon or in connection with the same and their rods, I cause the crank shaft end of
the "expansion eccentric rod" to travel in a straight line (or in some cases nearly so)
in lieu of the circle, it would describe if attached to a second eccentric, as is custo-
mary in the ordinary "hand adjusting" expansion gears; this straight line path or

page_text: "travel" of the second or "cut-off” eccentric rod end being across the line of action
of the main valve eccentric rod, and this at various and varying angles according to
the time, earlier or later, in the piston stroke or travel at which the cut-off is taking
place.
The arrangement of mechanical parts or details for producing this staight line
travel may be varied according to circumstances or the kind or size of engine,
but it must be such as will cause the said travel to be equal on both sides of
a given point in the line of the main valve action, and also allow of this line
crossing this central or given point at any required angle, as herein-before explained,
for instance, when it is directly across or at right angles to the main valve line of
action it constitutes the earliest possible cut-off, admitting no steam at all to the
cylinder. When at an angle of forty-five degrees from this, it will cut-off at about
quarter stroko," and when it is parallel with the main valve line of action (unless
arranged as is herein-after explained) it ceases to cut-off at all, and allows the steam
to enter both (either) ends of the cylinder, the intermediate angles or positions of
this travel or line of action (within this ninety degrees) constituting the various
times of "cutting off," or degrees or ratios of expansion, these angles being deter-
mined and controlled by the governer by or through any suitable or convenient
mechanical connection. It should be explained and understood that the effect or
result of this varying straight line path or travel is to alter both the "time" (lead)
and the "travel" of the cut-off valve with respect to the main valve.
In carrying into effect this part of my Invention I prefer generally to take
the action from the main valve eccentric rod at a point as near as is practicablo
to the eccentric and crank shaft, in some cases employing a pair of "dovetailed"
or other slides similar to a lathe "slide rest" placed vertically in some cases a pair of
radial arms and connecting link and rod, anu in others an internal "rack and pinion;"
this choice of "actions" or arrangements for producing the before-described straight
line travel depending upon the kind of engine the desired economy in first cost,
or other circumstances, but whichever of the before-named methods I employ, I
prefer that it should be supported by or attached to the pedestal which carries
(supports) the governor, thus securing simplicity and fewness of parts. When it is
necessary to extend the range of cut-off or expansion beyond the half of the piston
stroke I arrange the tune or angles of action of the before explained parts with
respect to each other, and to the circle or nearly circle formed by the main valve
eccentric rod at the point of connection or attachment, in such a manner as to give
the necessary lead which will extend the range and also increase the rapidity of
the cut-off.
The second part of this Invention consists in an improved method or system of
"relieving" or lightening the action of the valves, and is to a certain extent necessary
for the perfect and satisfactory action of the first part by rendering the work or
duty of the governor so light and easy that its control of the before-named valves,
cut-off, and speed of engine shall be prompt, certain, and satisfactory; this I effect
by the employment of wheels, rollers, or "recling levers," applied to, under, or in
connection with the cut-off plate or valve in contradistinction to the main valve as
heretofore employed. It will be evident that whilst it may be unsafe and therefore
impracticable to employ such a system or method of relief to the main slide valve
(as previous attempts have exemplified), its application to the cut-off valve or plate
or any similar plate upon the main valve will be safer and more satisfactory.
In carrying into effect this part of my Invention I employ four or any convenient
number of wheels, rollers, or "reeling levers," underneath, that is, for carrying or
supporting the cut-off valve or a similar plato or valve, these wheels, rollers, or
reeling levers being attached to or supported by, that is, working upon either the
sides of the main valve, or the stationary "valve scat face," according to circumstances
and the extent of relief required, the former relieving the cut-off valve only, and
the latter relieving both valves, without danger of leakage to the main valve faces,
from the fact that there will at all times be sufficient pressure left or allowed upon
that valve, notwithstanding the relief, to keep it tight upon its seat and face.

page_text: In casos where no expansion valve or plate is required I sometimes employ a
similar perforated plate and wheels, rollers, or reeling levers for relieving the main
valve, the said wheels, rollers, or reeling levers not being applied to the main
valve but to the perforated plate, as herein-before explained.
In the accompanying Drawings Fig. 1. is a plan partly in section of the
expansion gear at the earliest cut-off, and parts of a horizontal engine. Fig. 2 is
an elevation of part of the same. Fig. 3 is an enlarged face view of a modified
arrangement wherein levers and studs are substituted for one of the slides. Figs.
4 and 5, two arrangements for relieving the cut-off and main valves by the use of
the reeling levers and rollers; and Fig. 6 the application of the latter for relieving
the cut-off valves only.
The following letters of reference will also assist in making the construction of
the whole understood, viz. :-
a part of engine shaft; b, ordinary eccentric; c, eccentric rod; d, main valve;
e cut-off valve;f, part of governor standard; g, main pin of expansion gear; h, slide
upon or across the end of the pin g for carrying the light eccentrici; j, rod from
ditto to cut-off valve; k, sliding block inside the eccentric i; l, pin or stud for
carrying the same, and projecting from the side of the main valve eccentric rod c;
m, arm for coupling the gear to the governor by a vertical rod; n, wheel gear for
driving the governor, running loose upon the pin 9 and having no further connection
with the gear; o, o, reeling levers for relieving the cut-off valve, and through it,
in this instance, the main valve; p, p, bearing rollers for the same purpose;
q, q, ditto, ditto, bearing or working upon the side flanges of the main valvo,
and therefore relieving the cut-off valve only.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I wish it to be understood that I do not confine or restrict myself to the
precise details which I have described or referred to, as many variations and
modifications may be made therefrom without deviating from the principles or
main features of the said Invention; but what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein-before in part
recited Letters Patent is -
First. The arrangement and construction of governable expansion gear wherein
by the employment of slides, levers, or other suitable connecting mechanism between
the governor and the main valve, eccentric rod, or other equivalent, the crank shaft
end of the expansion or cut-off valve rod is made or caused to travel in a
straight line, or nearly so, at various angles from the perpendicular and from the
line of action of the main valve, and thus to vary the time of cutting off the steam,
by altering by the governor both the time ("lead") and "travel" of the cut-off
valve.
Second. The use and application of rollers, wheels, or reeling levers to the cut-
off valve or valves, in lieu of, and in contradistinction to, the main valve; thus
rendering practicable this method or system of obtaining relief from excessivo
pressure which, as herein-before explained, the direct application to the main valve
will not do.
In witness whereof, I, the said William Dawes, have hereunto set my hand
and seal, this Seventeeth day of November in the year of our Lord One
Witness,
J. PHEASEY,
100, Woodhouse Lane,
Leeds.
WILLIAM DAWES. (L.S.)