IMPROVED MECHANISM FOR STARTING AND WORKING STEAM ENGINES, PARTLY APPLICABLE TO OTHER PURPOSES
Year: 1869

page_text: LETTERS PATENT to William Macgeorge, Engineer, of No. 1, Castle
Court, Birchin Lane, London, and Arthur Rigg, junior, of the
City of Chester, Engineer, for the Invention of "IMPROVED MECHANISM
FOR STARTING AND WORKING STEAM ENGINES, PARTLY APPLICABLE TO OTHER
PURPOSES"
Sealed the 7th January 1870, and dated the 19th July 1869.
PROVISIONAL SPECIFICATION left by the said William Macgeorge
and Arthur Rigg at the Office of the Commissioners of Patents,
with their Petition, on the 19th July 1869.
We, WILLIAM MACGEORGE, Engineer, of. No. 1, Castle Court, Birchin
Lane, London, and ARTHUR RIGG, junior, of the City of Chester,
Engineer, do hereby declare the nature of the said Invention for
"IMPROVED MECHANISM FOR STARTING. AND WORKING STEAM ENGINES, PARTLY
APPLICABLE TO OTHER PURPOSES," to be as follows:-
The object of our Invention is to provide means for turuing cranks
over their dead centers in the case of single cylinder engines or
Price 8d1

page_text: compound engines where the dead centers of the cranks coincide in
position, and also to provide a cut-off expansion valve which can be
readily thrown out of action when starting the engine or whenever
desired.
.
The first part of our Invention is accomplished by fixing a cam upon
the engine shaft with a roller held against it by steam pressure or by
any other convenient means. This roller is alternately elevated, and
depresses itself as the cam revolves, and the position of the cam relatively
to the engine crank is so adjusted that power is borrowed to lift the
roller while the piston of the engine is about the middle part of its
stroke and given back again while the crank passes over its dead centers.
When desired steam may be admitted, and exhausted from behind the
piston or plunger which presses the roller against the cam
upou the
engine shaft, or instead of using a cam and roller the same results may
be obtained from link work or other mechanism arranged so that the
turning apparatus makes two reciprocations for every one of the engine
piston. Where an engine has to be reversed a second cam may be
applied, or the whole arrangement made in duplicate. With link work
or other systems a piston may be used and steam admitted on either
side. Lastly, these arrangements for turning cranks over their dead
centers may be used in all cases where a reciprocating motion has to
be converted into a circular one, and to motors where the source of
power is other than steam.
The second part of our Invention consists of two gridiron valves
working in grooves carried upon a slide valve and capable of closing
the apertures through the body of the slide valve by which steam is
admitted to the cylinder. The traverse of these grids is at right angles
to that of the slide valve, and may be produced by rollers and inclined
planes fixed upon the grids and the valve casing. The movement of
the slide valve opens and closes the grids, and the positions at which
they cut off steam may be determined by altering the stroke of the
slide valve or adjusting the positions of the inclined planes or rollers.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Macgeorge and Arthur Rigg in the Great
Seal Patent Office on the 7th January 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
MACGEORGE, Engineer, of No. 1, Castle Court, Birchin Lane, London,
and ARTHUR RIGG, junior, of the City of Chester, Engineer, send
greeting.
WHEREAS. Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of July, in the year of
our Lord One thousand eight hundred and sixty-nine, in the twenty-third
year of Her reign, did, for Herselt, Her heirs and successors, give and
grant unto us, the said William Macgeorge and Arthur Rigg, junior,
Her special licence that we, the said William Macgeorge and Arthur
Rigg, junior, our executors, administrators, and assigns, or such others
as we, the said William Macgeorge and Arthur Rigg, junior, 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
"IMPROVED MECHANISM FOR STARTING AND WORKING STEAM ENGINE, PARTLY
APPLICABLE TO OTHER PURPOSES," upon the condition (amongst others) that
we, the said William Macgeorge and Arthur Rigg, junior, 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 William Macgeorge and Arthur
Rigg, junior, do hereby declare the nature of our said Invention, and
¡n what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement (that is to say):-
The first part of our Invention provides for the turning of cranks over
their dead centers and rendering more uniform the velocity and power

page_text: of shafts driven by them. This object is accomplished by equalising
the power expended in each revolution.
The second part of our Invention consists of an expansion valve, the
apparatus for expansion being thrown in and out of gear by altering the
travel of the slide valve.
In order that the nature of our Invention may be more fully
understood we will proceed to describe the Figures upon the Sheets of
Drawings hereto attached and the mode in which the parts act.
Figure 1. represents one form of apparatus to carry out the first part
of our Invention as applied to a steam engine. A is the engine crank;
B, the main shaft; C, a cam fixed upon the shaft B; F, a plunger
working in the cylinder L and carrying a roller E in bearings so that
it can revolve freely. When steam is admitted through the pipe G into
the cylinder L and under the plunger F, and the cam C is in the
position shewn by Figure 1, then the crank A will be turned over its
dead center by this apparatus in the direction of the arrow from the
position shewn in Figure 1 towards that shewn in Figure 2.
Figures 1, 2, 3, 4, and 5 shew different positions of the apparatus
during one entire revolution of the main shaft. When this mode of
carrying out our Invention is to be applied in the reverse as well as
in the forward action of the engine another cam D, as shewn dotted in
Figure 1, may be fixed upon the main shaft B and by suitable apparatus
be brought into gear with the roller E whenever required.
In Figure 6 is shewn an arrangement of linkwork by which the object
of our Invention may be accomplished. Upon the main shaft B there
is a crank K joined by a connecting rod with the links (a, b,) and (b, c).
The link (a, b,) oscillates on its center (a) and is connected by means
of the link (b, c,) with a slide block P, and a piston inside the cylinder L.
When the main shaft B turns round then the piston in the cylinder L
moves backwards and forwards. When steam is admitted under this
piston the links (a, b,) and (b, c,) are forced outwardly from their
position, as shewn in the Drawing, so acting upon the crank K and
turning the shaft B in the direction of the arrow. By means of a slide
valve or other arrangement steam may be admitted on either side of
the piston in the cylinder L, as required, and for this purpose we prefer
to connect the valve spindle R with the weigh shaft or reversing lever

page_text: which moves the link motion W (Figure 1). An oscillating cylinder
may be used instead of the fixed cylinder L and the link (b, c).
Another mode of carrying out this first part of our Invention is shewn
in Figure 7. A being the crank, and B the main shaft, as before
described. Upon the shaft B is a wheel P gearing into another Q
which makes two revolutions for every one of the wheel P, upon the
wheel Qor convected with it there is a crank pin K and other
mechanism, as shewn. The valve spindle R is either moved by the
weigh bar together with the link W (Figure 1), by an independant
handle in order to reverse the pressure. This part of our Invention can
be applied to any machinery in which motive power is conveyed by
means of cranks or substitutes for them, and is not therefore confined to
steam engines.
or
As examples of other applications Figure 8 represents a lathe with a
cam arrangement applied. A spring S here takes the place of the
cylinder L and plunger F (Figure 1).
Figure 9 represents an application of this first part of our Invention
to a winch handle A. Here a spring S which presses in either direction
takes the place of the piston in L and links (a, b,) and (b, c,) Figure 6.
One method of carrying into effect the second part of our Invention
is represented in the upper part of Figure 1 and Figure 10.
M is a
slide valve; N, N, its steam ports covered by grids O, sliding in
grooves and carried up and down with the valve. When the openings
in these grids coincide with those through the body of the slide steam
passes into the cylinder in the usual manner, but a sufficient movement
of the grids closes the steam passages. This movement is accomplished
by adjustable stops fastened upon the valve case acting upon the grids
and moving them backwards and forwards. The link W works the
valve in the usual manuer, but when at or near to its longest stroke
the stops upon the valve case operate on the grids, so closing the steam
ports, but with a shorter stroke of the valve these stops do not come
into operation, and therefore by the action of the inner stops alone the
valve ports are kept open.
Having thus described the nature of our Invention, and the manner in
which the same may be carried into effect, we would have it understood
that we do not confine or restrict ourselves to the precise details or

page_text: arrangements described, as variations can be made without deviating
from the main features of our Invention; but what we claim is, a
combination of pressure with machinery for rendering more uniform
the velocity and power of shafts driven by cranks, and for turning the
cranks over their dead centers, substantially as herein described.
In witness whereof, we, the said William Macgeorge and Arthur
Rigg, junior, have hereunto set our hands and seals, this Sixth
day of January, in the year of our Lord One thousand eight
hundred and seventy.
W. MACGEORGE.
(L.S.)
ARTHUR RIGG, JUNIOR. (L.S.)