IMPROVEMENTS IN THE MEANS OF STARTING STEAM ENGINES
Year: 1874

page_text: LETTERS PATENT to John Frederick Spencer, of No. 28, Great George
Street, Westminster, in the County of Middlesex, and William
Inglis, of Bolton, in the County of Lancaster, for the Invention of
" Tunna ***
"
"
IMPROVEMENTS IN THE MEANS OF STARTING STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said John Frederick Spencer
and William Inglis at the Office of the Commissioners of Patents,
with their Petition, on the 23rd April 1874.
We, JOHN FREDERICK SPENCER, of No. 28, Great George Street,
Westminster, in the County of Middlesex, and WILLIAM INGLIS, of
Bolton, in the County of Lancaster, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MEANS OF STARTING STEAM
ENGINES," to be as follows:-
The object of the present Invention is to secure certainty in starting
in cither direction single engines having only one crank, or two or more

page_text: engines working together having cranks in line with or opposite to each
other, or nearly so, and to avoid the risk to which such engines are
liable of stopping on the centres. For this purpose we provide a supple-
mentary engine of small dimensions as compared with the main or
working engine or engines. The piston of this supplementary or starting
engine is permanently connected by the usual connecting rod to a crank
or disc on the main shaft or on a countershaft geared thereto, the pin of
such crank or disc being placed at about right angles with the main or
driving crank or cranks, or in such position as to act at right angles, or
nearly so, to the main crank or cranks. The supplementary engine is
provided with suitable valves or a side worked by hand gear when it is
used as a starting engine, and its eduction may communicate with the
main condenser. In ordinary working the piston of the supplementary
engines is simply moved by the main engine without steam pressing on
it, the valves or slide being so arranged and set as to permit free passage
from the one end of the cylinder to the other, or from both ends to the
engines working together having cranks in line with or opposite to each
other, or nearly so, and to avoid the risk to which such engines aro
liable of stopping on the centres. For this purpose we provide a supple-
mentary engine of small dimensions as compared with the main or
working engine or engines. The piston of this supplementary or starting
engine is permanently connected by the usual connecting rod to a crank
or disc on the main shaft or on a countershaft geared thereto, the pin of
such crank or disc being placed at about right angles with the main or
driving crank or cranks, or in such position as to act at right angles, or
nearly so, to the main crank or cranks. The supplementary engine is
provided with suitable valves or a side worked by hand gear when it is
used as a starting engine, and its eduction may communicate with the
main condenser. In ordinary working the piston of the supplementary
engines is simply moved by the main engine without steam pressing on
it, the valves or slide being so arranged and set as to permit free passage
from the one end of the cylinder to the other, or from both ends to the
condenser or to the atmosphere.
The dimensions of the supplementary engine must be such as to ensure
sufficient power to move the main engine or engines off their dead
centres, and it may therefore be used for turning the main engine or
engines when they are not under steam.
The position of the supplementary engine may be varied according to
the arrangement of the main or driving engine or engines; by preference
for engines having inverted cylinders we place the cylinder of the
supplementary engine inverted over the end of the crank shaft, con-
necting it to a pin on an outside crank or disc on the main crank shaft,
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Frederick Spencer and William Inglis in tho
Great Seal Patent Office on the 21st October 1874.

page_text: the County of Middlesex, and WILLIAM INGLIS, of Bolton, in the County
of Lancaster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of April, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-seventh year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto us, the said John Frederick Spencer and
William Inglis, Her special license, that we, the said John Frederick
Spencer and William Inglis, our executors, administrators, and assigns,
or such others as we, the said John Frederick Spencer and William
Inglis, 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 THE MEANS OF STARTING STEAM ENGINES," upon the
condition (amongst others) that we, the said John Frederick Spencer
and William Inglis, our executors or administrators, by an instrument
in writing under our or their hands and seals, or under the hand and
seal of one of us or them, 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 Patont
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, tho said Jolin Frederick Spencer, on behalf
of myself and the said William Inglis, do hereby declare the nature of
the said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following
statement thereof, reference being had to the accompanying Sheet of
Drawings, and to the figures and letters marked thereon, that is to
say:―
The object of the present Invention is to secure certainty in starting
in either direction single engines having only one crank, or two or more
engines working together having cranks in line with or opposite to each
other, or nearly so, and to avoid the risk to which such engines are
liable of stopping on the centre. For this purpose we provido a supple-..

page_text: position in which the pressure on the main piston can act effectively on
its crank.
Fig. 2 represents on an enlarged scale a section of a slide valve
adapted to the supplementary engine. K, K, are the passages to the
ends of the supplementary cylinder; and L, the exhaust passage which
may lead to the atmosphere, main condenser, or elsewhere as thought
desirable. This slide valve acts as the common D slide, but the exhaust
cavity in the slide is made sufficiently long to allow the opposite ends of
the cylinder to be in free communication with each other and with the
exhaust passage when the slide is in its middle position, thus providing
against accumulation of steam or water in either cud of the cylinder
which would cause power to be wasted in driving the supplementary
engine when it is not in use for starting the main engine. The slide
valve of the supplementary engine is moved by means of a hand wheel M
fixed on a spindle N, a screw on which spindle works in a nut mounted
on one arm of a crank lever O; the other arm is connected to the slide
rod P by the rod Q. By turning the hand wheel the slide is moved so
as to admit steam to either end of the supplementary cylinder whilst the
other end continues in communication with the exhaust.
The application of this Invention is not confined to engines having
only one main cylinder, but it may also be applied with advantage to
compound engines having two or more cylinders working on to one
crank or on to cranks in line with or opposite to each other, or nearly
so, their starting from all positions being in such cases uncertain.
The position of the supplementary engine and the arrangement of
hand gear for moving its slide valve as well as the form of the latter
may be varied for different types of engines, and cocks or valves com-
municating with the condenser, atmosphere, or elsewhere may be fitted
to both ends of the supplementary cylinder to ensure freedom of motion
to its piston when it is driven by the main engine.
Having thus described the nature of our Invention, and in what
manner the same is to be performed, we claim, the use, for the purpose
of starting steam engines, of a supplementary engine arranged to act on
the main shaft by a crank set at such an angle to the main crank or
cranks as to be effective when the latter are at or near their dead points,

page_text: such supplementary engine being provided with hand valve gear, sub-
stantially as hercin described.
•
In witness, whereof, I, the said John Frederick Spencer, have
hereunto set my hand and scal, this Nineteenth day of October,
in the year of our Lord One thousand eight hundred and seventy-
four.
JOHN FREDERICK SPENCER. (L.S.)