IMPROVEMENTS IN DISTRIBUTING VALVES FOR MOTIVE-POWER ENGINES
Year: 1875

page_text: LETTERS PATENT to John Darlington and James Donnithorne Thomas,
of 2, Coleman Street Buildings, Moorgate Street, in the City of
London, for the Invention of "IMPROVEMENTS IN DISTRIBUTING VALVES
FOR MOTIVE-POWER ENGINES."
Sealed the 6th December 1875, and dated the 24th June 1875.
PROVISIONAL SPECIFICATION left by the said John Darlington and
James Donnithorne Thomas at the Office of the Commissioners of
Patents, with their Petition, on the 24th June 1875.
We, JOHN DARLINGTON and JAMES DONNITHORNE THOMAS, of 2,
Coleman Street Buildings, Moorgate Street, in the City of London, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
DISTRIBUTING VALVES FOR MOTIVE-POWER ENGINES,” to be as follows :—
These improvements relate to cylindrical rotating valves used for the
purpose of distributing the pressure fluid to motive-power engines,
which receive their motion from any fluid under pressure.

page_text: In constructing our valve we so arrange the passages that one set of
passages in the interior of the valve is constantly in communication
with the fluid pressure, and that another set of passages also in the
interior of the valve is constantly in communication with the exhaust.
Suitable openings are made through the outside shell of the valve 5
communicating with these several passages, which openings, as the
valves revolves, place the cylinder passages alternately in communication
with the pressure or with the exhaust.
We so arrange these openings that the pressure shall tend to keep the
valve in equilibrium, that is, that one set of pressure and exhaust 1
openings shall be balanced by other similar sets of openings in other
parts of the circumference of the valve, and to do this effectually we
cause the valve to be rotated at a different speed from that of the engine,
such difference of speed being governed by the number of portways to
which the fluid is to be distributed, and the number of openings for this 1
purpose in the periphery of the valve.
•
We purpose driving the valve in one arrangement as follows:-An
externally geared wheel is keyed on a driving spindle, which rotates
equally with the engine; into this is geared a pinion carried on a stud
fixed in a lever arm, free to be moved about the centre of the said a
driving spindle. This pinion also gears into an internally geared wheel,
which is keyed on to the cylindrical valve.
The proportions of these wheels may be varied to suit the various
relative velocities of the engine and valve.
By shifting the lever arm carrying the intermediate pinion the
relative positions of the valve with the engine crank may be altered and
the cut off varied, or the engine may be stopped or reversed.
We do not confine ourselves to the arrangement of gearing here
described for rotating the valve, as the same movement may be obtained
from any revolving shaft by means of a train of spur or bevel gearing,
the proportion and disposition of the wheels being varied to suit the
varying conditions under which the pressure fluid has to be distributed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Darlington and James Donnithorne Thomas
in the Great Seal Patent Office on the 24th December 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOHN
DARLINGTON and JAMES DONNITHORNE THOMAS, of No. 2, Coleman
Street, Buildings, in the City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of June, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto us, the said John Darlington and James
Donnithorne Thomas Her special licence that we, the said John
Darlington and James Donnithorne Thomas, our executors, administra-
tors, and assigns, or such others as we, the said John Darlington and
James Donnithorne Thomas, our 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 "IMPROVEMENTS IN DISTRIBUTING VALVES FOR MOTIVE-
POWER ENGINES," upon the condition (amongst others) that we, the said
John Darlington and James Donnithorne Thomas, our executors or
administrators, by an instrument in writing under our, 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 within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that we, the said John Darlington and James
Donnithorne Thomas, do hereby declare the nature of our 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 accompanying Sheets of Drawings, and to the figures
and letters marked thereon, that is to say :—
.
These improvements relate to cylindrical rotating valves used for the

page_text: purpose of distributing the pressure fluid to motive-power engines,
which receive their motion from any fluid under pressure.
In constructing our valve we so arrange the passages that one set of
passages in the interior of the valve is constantly in communication
with the fluid pressure, and that another set of passages, also in the 5
interior of the valve, is constantly in communication with the exhaust.
Suitable openings are made through the outside shell of the valve
communicating with these several passages, which openings, as the
valve revolves, place the cylinder passages alternately in communication
with the pressure or with the exhaust.
We so arrange these openings that the pressure shall tend to keep
the valve in equilibrium, that is, that one set of pressure and exhaust
openings shall be balanced by other similar sets of openings in other
parts of the circumference of the valve; and in order that we may so
arrange these said parts effectually we cause the valve to be rotated at 1
a different speed if necessary from that of the engine, such difference
of speed being governed by the number of portways to which the fluid
is to be distributed, and the number of openings for this purpose in the
periphery of the valve.
We purpose driving the valve. in one arrangement as follows:-An :
externally geared wheel is keyed on a driving spindle, which rotates
equally with the engine; into this is geared a pinion carried on a stud
fixed in a lever arm, free to be moved about the centre of the said
driving spindle. This pinion also gears into an internally geared wheel,
which is keyed on to the cylindrical valve.
The proportions of these wheels may be varied to suit the various
relative velocities of the engine and valve.
By shifting the lever arm carrying the intermediate pinion the relative
positions of the valve with the engine crank may be altered and the
cut off varied, or the engine may be stopped or reversed.
We do not confine ourselves to the arrangement of gearing here
described for rotating the valve, as the same movement may be obtained
from any revolving shaft by means of a train of spur or bevel gearing,
the proportions and disposition of the wheels being varied to suit the
varying conditions under which the pressure fluid has to be distributed,
such train of gearing being always arranged substantially as described
1

page_text: and illustrated, that is to say, so that the intermediate pinion between
the driving wheel and the driven may be moved around the driving
wheel at pleasure while still gearing into both, thus altering the relative
positions of one wheel with the other.
Figs. 1, 2, 3, 4, 5, and 6 on Sheet 1 represent a valve arranged in
accordance with our Invention for distributing the motive fluid to a set
of three cylinders arranged as shewn in Figs. 14 and 15 on Sheet 2, that
is, as in Fig. 14. The cylinders are arranged in the same plane radiating
from a common centre, making angles of about 120 degrees with each
other.
The cylinders are single acting, that is to say, the pressure is admitted
to and exhausted from the outer ends of the cylinders only, the inner
ends being open towards a central chamber or cavity, into which the
exhaust steam is carried by preference. Each of these cylinders is fitted
with a piston. Each of these pistons has a connecting rod, and are all
connected to one crank working within the central chamber or cavity,
or as in Fig. 15 the cylinders may be arranged in a line side by side
above a chamber or cavity through which the crank shaft passes, the
cranks being set at an angle of about 120 degrees with each other.
Fig. 1 is a longitudinal section through the valve casing, the valve
itself being shewn in this Figure in elevation; Fig. 2 is a front elevation;
Fig. 3 is a plan; Fig. 4 is a section on line E, F; Fig. 5 is a section on
C, D; and Fig. 6 is longitudinal section of the valve itself taken
through the pressure passages, the same letters and figures of reference
indicating corresponding parts in all the corresponding Figures.
a, a, a, are the passages to which the steam or other pressure is to
be distributed; c is a cavity into which the exhausted steam passes after
leaving the valve, communicating by passages b, b, with the central
cavity or with the atmosphere direct, as may be arranged; e is the inlet
pipe by which the steam is led to the valve; f.f, are steam passages and
9. 9, exhausting passages formed in the interior of the valve, and com-
municating with the pressure and exhaust chambers; openings h, h,
and i, i, are made through the outside shell of the valve by which the
steam may pass to or from the interior passages formed in the valve, the
length of these openings in the direction of the circumference being
governed by the portion of an entire revolution, during which it is
desired to keep either set of passages in communication with the passages

page_text: a, a, a. We so arrange these openings that the pressures operating on
the valve may balance each other, and by keeping the valve in equi-
librium reduce the friction and consequent wear and power required to
rotate the valve to a minimum.
In the arrangements shewn on Figs. 14 and 15 on Sheet 2, to which i
the valve arranged as shewn on Figs. 1, 2, 3, 4, 5, and 6 on Sheet 1 is
applicable, it is necessary that the valve should rotate at one half the
speed of the crank, and in the opposite direction. We therefore cause
the valve to be rotated as follows:-k is a shaft attached to the crank
shaft and revolving with it, and running through the centre of the valve 1
but not attached to it. On the end of this shaft is fixed an externally
geared pinion wheel 7. This pinion gears into an intermediate pinion m
running loose on stud n fixed to a moveable lever o. The pinion malso
gears into an internally geared wheel p, which is fixed to and revolves
with the valve, and which is twice the diameter of the driving pinion 2. 1
It will be seen from this arrangement that the valve is driven as required
at one half the speed of the crank and in an opposite direction.
When it is required to reverse the motion of the engine the moveable
lever o which is pivotted on the shaft k and capable of being moved
around it is thrown over into a new position carrying the pinion m with 2
it, and consequently the wheel p affixed to the valve, thus altering the
relative positions of the valve and the crank, and directing the steam
from the piston of one cylinder on to the piston of another at pleasure.
and this may be done either while the engine is in motion or at rest.
When it is never required to reverse the engine the stud n may be fixed 2
to an immoveable support 7, as shewn in Figs. 7 and 8 on Sheet 2.
It is evident that this arrangement of valve may be adapted to almost
any form of engine to which it may be desired to distribute fluid
pressure.
Fig. 16 on Sheet 2 shews an arrangement in which two double acting 8
cylinders arc coupled to one crank shaft, the cranks being directly
opposite to each other and in the same plane. For this arrangement

page_text: The passages in the valve shewn in Figs. 10, 11, 12, and 18 are
arranged as shewn on Figs. 1, 2, 3, 4, 5, and 6 on Sheet 1, the valve
being rotated as follows :-
:— is a shaft connected to the crank shaft and
revolving with it; on the end of this shaft is fixed an externally geared
pinion wheel; this pinion gears into another pinion of equal diameter m
which is fixed to and revolves with another pinion w of less diameter,
which again gears into a pinion wheel p affixed to the valve. The
wheel p is twice the diameter of the wheel to, consequently the valve is
driven at one half the speed of the the crank shaft in the same direction,
this being the motion required to distribute pressure to the arrangement
of engine above alluded to. The wheels m and ware fixed to each
other and revolve together, and are carried by the moveable lever o
when it is required that the engine should be capable of being reversed.
Where it is required to distribute steam to an engine arranged as in
Figs. 17 and 18 on Sheet 2, that is, either four single acting cylinders
acting on one crank pin, or two double acting cylinders, the cranks to
which they are connected being set at right angles, or thereabouts, the
arrangement of valve shewn in Figs. 7, 8, and 9 on Sheet 2 would be
applicable, Fig. 7 being a longitudinal section through the valve and its
casing; Fig. 8 a front elevation and Fig. 9 a section on the line C, D.
From these Figures it will be seen that there are three sets of steam and
three sets of exhaust ports and passages in the valve, and that it is
necessary that the valve should be rotated at one-third the speed of the
engine and in the opposite direction. To accomplish this the valve is
driven as shewn in Figs. 7, 8, and 9, which is a similar arrangement to
that shewn in Figs. 1, 2, and 3 on Sheet 1, with this difference, that the
proportion of the wheels to p is as three to one instead of two to one
as before.
Having now described and particularly ascertained the nature of our
said Invention, and in what manner the same is or may be used or
carried into effect, we would observe in conclusion that what we consider
to be novel and original and therefore claim as the Invention secured to
us by the herein-before in part recited Letters Patent is,—
First. Constructing rotating cylindrical valves for distributing fluid
pressure substantially as herein described and illustrated.
Second. Driving rotating cylindrical valves for distributing fluid
pressure by the arrangements of gearing herein described and illustrated.

page_text: Third. The combination of the cylindrical rotating valves and the
gear for driving them as herein described and illustrated.
In witness whereof, we, the said John Darlington and James
Donnithorne Thomas, have hereunto set our hands and seals, this
Twenty-fourth day of December, in the year of our Lord One 5
thousand eight hundred and seventy-five.