IMPROVEMENTS IN THE CONSTRUCTION AND REGULATION OF STEAM ENGINES, AND APPARATUS THEREFOR."
Year: 1880

page_text: LETTERS PATENT to Henry Davey, of Leeds, in the County of York, for an
Invention of "IMPROVEMENTS IN THE CONSTRUCTION AND REGULATION OF
STEAM ENGINES, AND APPARATUS THEREFOR."
PROVISIONAL SPECIFICATION left by the said Henry Davey at the Office
of the Commissioners of Patents on the 30th December 1880.
HENRY DAVEY, of Leeds, in the County of York. "IMPROVEMENTS IN
THE CONSTRUCTION AND REGULATION OF STEAM ENGINES, AND APPARATUS
THEREFOR."
My Invention relates to the construction of small and easily manageable steam
engines, and the application of such an engine as a subsidiary engine to work or
control the valves of a main engine in such a manner that the direction of rotation
and speed of the main engine shaft are determined and governed by the subsidiary
engine. The apparatus which I employ for regulation may be variously modified
to suit the particular kinds of engines to which it is applied. The subsidiary
engine so applied may be of simple form, having only one cylinder and a flywheel,
but for convenience of reversal it is preferable to employ a small engine having
two cylinders with their pistons working cranks at right angles to one another on
a shaft, which in order to ensure greater regularity of movement should carry one
or more heavy flywheels. I construct such an engine, which may be employed
either for producing motive power itself or for governing a main engine, in the
following manner:-Between the two cylinders I arrange two cylindrical slide
cases, each fitted with a double piston slide governing ports to the two ends of each
cylinder respectively. From the middle of each slide case there is a passage to a
side cavity, and from both ends of each slide case there are passages to another
side cavity. These two cavities have ports governed by a slide, by moving which
by hand either cavity can be put in communication with the steam supply, the
other being made to communicate with the exhaust. Thus either the middle
or the ends of the two slide cases can be supplied with steam while the ends
or the middle open to the exhaust. The slides being worked in the usual

page_text: way by eccentrics on the shaft according as the one or the other cavity is made
the supply cavity, the engine shaft is caused to revolve in the one direction or the
other. In applying a subsidiary engine to control a main engine, I connect the shaft
of the subsidiary engine to the slide or valves of the main engine, providing suitable
stops, so that the subsidiary engine cannot over run the main engine, although the
main engine can over run the subsidiary engine. In case therefore of the main
engine beginning to out run the speed to which the subsidiary engine is timed, the
valves of the main engine will be worked so far inconsistently with the movements
of the engine that these will be retarded. When the main engine has to be
reversed it is only necessary to reverse the subsidiary engine, and the main engine
valves being thereby worked consistently with reversal of the main engine such
reversal will ensue. The speed of the subsidiary engine being regulated by any
known governor, the speed of the main engine becomes regulated to be consistent
with the movements of its valves as determined by the subsidiary engine.
When it is desired to regulate the main engine by varying the cut off instead of
working the main engine valves directly from the subsidiary engine, I work theni
therefrom through sun and planet gearing in the following manner:-I fit the
eccentric of the main slide loose on the main shaft, and I also fit loose on the main
shaft a sleeve which is driven by the subsidiary engine. On the main shaft I
arrange one or more planet wheels which gear with teeth on the sleeve, and also
with teeth on the eccentric, so that the speed of the sleeve being determined by
the subsidiary engine when the main shaft revolves at other than its normal speed, the
planet wheels thereon give such differential movement to the eccentric as to shift its
position relatively to the main shaft, causing the main slide to cut off earlier or later
as the case may be. Stops are provided to prevent this differential movement from
exceeding certain limits. Instead of thus varying the action of the main slide, an
expansion slide working on the back thereof may be driven by an eccentric subject
to the differential action above described, the eccentric of the main slide revolving
in that case in time with the main shaft.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Davey in the Great Seal Patent Office on the 21st June
1881.
"IMPROVEMENTS IN
HENRY DAVEY, of Leeds, in the County of York.
THE CONSTRUCTION AND REGULATION OF STEAM ENGINES, AND APPARATUS
THEREFOR."
My Invention relates to the construction of small and easily manageable steam
engines, and the application of such an engine as a subsidiary engine to work or
control the valves of a main engine in such a manner that the direction of rotation
and speed of the main engine shaft are determined and governed by the subsidiary
engine. The apparatus which I employ for regulation may be variously modified
to suit the particular kinds of engines to which it is applied. The subsidiary
engine so applied may be of simple form, having only one cylinder and a flywheel,
but for convenience of reversal it is preferable to employ a small engine having
two cylinders with their pistons working cranks at right angles to one another on
a shaft which, in order to ensure greater regularity of movement, should carry one
or more heavy flywheels. I construct such an engine, which may be employed
either for producing motive power itself or for governing a main engine, as I will
describe referring to Fig. 1, which is a plan, partly in section, and Fig. 18, which is
a transverse section (shewn inverted) through the cylinders and back part of the
slide casing; a and b are the two cylinders, the pistons of which work cranks at
right angles to each other on the shaft 8. Between the two cylinders is a space
containing two cylindrical slide cases and a chamber between them divided into
compartments, the back compartment h receiving steam supply and the front
compartment & being divided by horizontal partitions into three compartments, by
the middle one of which exhaust is discharged. The cylindrical slide cases are
fitted with double piston slides c and d, which are worked by eccentrics on the
shaft 8.
From the slide cases there are central apertures and passages e leading to
the uppermost compartment of k, and there are end apertures and passages i
leading to the lowest compartment of k. The partition separating h from k has
three parts l, f, m, opening respectively into the lowest, the middle, and the
highest compartments of k, and these ports are governed by a D slide which can
be moved up or down by hand. When it is moved up steam enters by the port 1,
the lowest compartment of k, and thence passes by the aperture i to the ends of
the slide cases, whence by the movement of the slides c and d it passes alternately
to the ends of the cylinders a and b. From these the exhaust passes by the
apertures e to the highest compartment of k and thence by the ports m and f to
the middle compartment whence it is discharged. When the D slide is moved down
the direction of the steam supply and discharge is reversed, the supply entering the
slide cases by the middle apertures e and being discharged by the end apertures i,
and this obviously has the effect of reversing the movement of the engine.
In applying a subsidiary engine (which may be of the kind described, or may, as
stated above, have only one cylinder with a heavy fly wheel) to control a main
engine, I connect the shaft of the subsidiary engine to the slide or valves of the
main engine, providing suitable stops, so that the subsidiary engine cannot outrun
the main engine, although the main engine can outrun the subsidiary engine. In
case therefore of the main engine beginning to outrun the speed to which the
subsidiary engine is timed, the slide or valves of the main engine will be worked
so far inconsistently with the movement of the engine that it will be retarded and
brought back to its normal speed as determined by the subsidiary engine. Also

page_text: when the main engine has to be reversed it is only necessary to reverse the sub-
sidiary engine, and the slide or valves of the main engine being thus altered in
their movement so as to be consistent with reversal of the main engine such
reversal will ensue. The speed of the subsidiary engine being regulated by any
known governor, the speed of the main engine becomes regulated so as to be con-
sistent with the movements of its slide or valves, as determined by the subsidiary
engine. Fig. 2 is a plan partly in section of a compound engine thus regulated by
means of a subsidiary engine, and Fig. 3 is a section of the main engine shaft
shewing a pair of the eccentrics for working the slides. a is the subsidiary engine,
the shaft of which has a pinion g gearing with a wheel h, which runs loose on the
shafts of the main engine carrying with it a pair of eccentrics o, o. Another pair
of eccentrics n, n, are fixed on the shaft 8. Each couple n, o, of the eccentrics by
means of a sway beam m, to the opposite ends of which they are respectively
connected, works one of the main engine slides. When the two eccentrics n and o
are revolving with the same velocity the slides are moved so as to alternate the
steam supply and discharge of the main engine in the regular way; but if, owing
to acceleration of the main engine, the one eccentric n of each couple should outrun
the other eccentric o to the extent limited by a stop working in a slot of n, then
the movements imparted to the opposite ends of the sway beam m will neutralise.
each other, and the slides of the main engine will remain stationary until the speed
of the main engine becomes restored to coincidence with that of the subsidiary
engine. Even if the main engine should not so far outrun the subsidiary engine as to
bring the stop to the end of its slot, the strokes of the main slides will be more or
less lessened, and the steam supply will be thus reduced so as to retard the main
engine.
When it is desired to regulate the main engine by varying the cut off, I work
the main engine valves by sun and planet gearing from the subsidiary engine in
the following manner:
I fit the eccentric of the main slide loose on the main shaft, and I also fit loose on
the main shaft a sleeve which is driven by the subsidiary engine. On the main
shaft I arrange one or more planet wheels which gear with teeth on the sleeve and
also with teeth on the eccentric, so that the speed of the sleeve being determined
by the subsidiary engine when the main shaft revolves at other than its normal
speed the planet wheels thereon give such differential movement to the eccentric as
to shift its position relatively to the main crank, causing the main slide to cut off
steam earlier or later, as the case may be. Stops are provided to prevent this
differential movement exceeding certain limits. Instead of thus varying the action
of the main slide, an expansion slide working on the back thereof may be driven by
an eccentric subject to the differential action above described, the eccentric of the
main slide being in that case fixed on the crank shaft. Fig. 4 is a plan partly
in section of a pair of engines having cut off slides worked in this manner.
Fig. 5 is a plan to an enlarged scale, partly in section, and Fig. 5ª is a
section shewing the sun and planet gearing. The main slides are worked by
eccentrics m, n, fixed on the crank shaft s. The cut off slides on the back of the
main slides are worked by eccentrics o, o, each of which is fixed on a sleeve t loose
on the shaft. The subsidiary engine a by means of a pinion g works a wheel h
fitted to revolve freely round a disc v that is fixed on the shaft s, and has several
planet pinions i mounted on both sides of it. These pinions i gear with internal
teeth of the wheel h, and with external teeth p on the eccentric sleeves t.
As long
as the main shafts and the wheel h revolve uniformly together, the action of the
eccentrics o on the cut off slides is normal, but should the speed of the shaft a differ
from that of the wheel h, which is determined by the subsidiary engine, then the
planet pinions i being thus made to travel along the teeth of h move the sleeves t
so as to set the eccentrics o forwards or backwards, as the case may be, relatively
to the main eccentrics n, thus causing the cut off to be varied. The sun and planet
gear may be modified by using bevil wheels and pinions, as shewn in part plan at
Fig. 6; and to an enlarged scale in part plan at Fig. 7; and in elevation at Fig. 7*.

page_text: In this case the bevil pinions i are mounted on pins projecting from the shaft 8,
and they gear on one side with bevil teeth on the wheel h, and on the other side
with bevil teeth p on the sleeves of the eccentrics o.
The subsidiary engine may be combined with the main slide, and the speed
controlled by a governor, as shewn in Fig. 8, which is a plan, partly in section, of
a pair of engines thus arranged; Fig. 9 is a section of the main shaft shewing the
stop for the wheel y; and Fig. 10 is a section to an enlarged scale of the socket for
the governor spindle. In this construction the pistons a and b of the subsidiary
engine are rigidly attached to the main slides, and are connected to cranks v on a
counter-shaft, a wheel z on which gears with the wheel y. This wheel is loose on
the main shaft 8, but its movement thereon is limited by a stop to half a revolution,
and thus the countershaft can only turn half round relatively to the main shaft 8,
so as to suit either direction of rotation. The alternation of steam to act on the
pistons a and b is effected by subsidiary slides, which are not shewn, but which
may be worked by eccentrics x, x. On the countershaft are mounted the bevil
planet pinions i, which gear on one side with bevil teeth on the cut off eccentrics o,
and on the other side with bevil teeth on a sleeve u that is loose on the countershaft,
and has on it a bevil wheel h driving a pinion g on the spindle of a governor n.
When owing to acceleration the governor balls tend to fly outwards the coned
endt of the governor spindle is drawn in opposition to a spring into its conical
socket, which operates as a friction brake, retarding the governor, and consequently
retarding the wheel hand sleeve u. This retardation of u acting through the
planet pinions i causes the eccentrics o to be shifted relatively to the cranks v,
thus varying the cut off.
Having thus described the nature of my Invention, and in what manner the
same is to be performed, I claim,―
First. The construction of engine herein described with reference to Figs. 1 and 1*,
having its slide cases communicating with supply and discharge passages by parts
governed by a slide, by the manual movement of which the engine can be reversed.
Second. The combination of a subsidiary engine with eccentrics of a main
engine, so that the speed and direction of rotation of the main engine shaft are
controlled by that of the subsidiary engine shaft, substantially as herein described
with reference to Figs. 2 and 3.
Third. Connecting the eccentrics of a main engine through sun and planet gear
to the shaft of a subsidiary engine, substantially as and for the purposes herein
described with reference to Figs. 4, 5, 5, and Figs, 6, 7, and 7°.
Fourth. Working the slides of a main engine by a subsidiary engine and con-
necting the cut off eccentrics through sun and planet gear to a governor, substantially
as herein described with reference to Figs. 8, 9, and 10.
In witness whereof, I, the said Henry Davey, have hereunto set my hand
and seal, this Eighteenth day of June, in the year of our Lord One thousand
eight hundred and eighty one.
HENRY DAVEY. (L.S.)