A NEW OR IMPROVED BRAKE FOR COLLIERY AND OTHER STEAM ENGINES
Year: 1856

page_text: LETTERS PATENT to James Griffiths, of Wolverhampton, in the County
of Stafford, Engineer, for the Invention of "A NEW OR IMPROVED BRAKE
FOR COLLIERY AND OTHER STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said James Griffiths at the
Office of the Commissioners of Patents, with his Petition, on the 22nd
February 1856.
I, JAMES GRIFFITHS, of Wolverhampton, in the County of Stafford,
Engineer, do hereby declare the nature of the Invention for "A NEW OR
IMPROVED BRAKE FOR COLLIERY AND OTHER STEAM ENGINES," to be as follows:--
In the ordinary brake for colliery engines, a piece of wood or other sub-
stance is made to press upon a pulley fixed on the main shaft of the engine
or the drum shaft. My new or improved brake consists of one or two nearly
semicircular pieces of wood or other substance, made to press upon the edge
of a toothed wheel instead of a smooth pulley. In applying my Invention
to colliery engines, I make the said pieces of wood press upon the toothed
wheel situated on the drum shaft, and by which motion is transmitted from
the axis of the fly wheel to the said drum; but I do not limit myself to any
particular position of the wheel to which the pressure is applied, the essence
of my Invention consisting in making a brake by pressing upon a toothed
wheel instead of a smooth pulley. Although my Invention is specially
applicable to colliery engines, yet it may be applied to steam engines in
general.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Griffiths in the Great Seal Patent Office on the
20th August 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
GRIFFITHS, of Wolverhampton, in the County of Stafford, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of February, in the year of our
Lord One thousand eight húndred and fifty-six, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said James Griffiths, Her special licence that I, the said James Griffiths, my
executors, administrators, and assigns, or such others as I, the said James
Griffiths, my 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 "A NEW OR IMPROVED BRAKE FOR
COLLIERY AND OTHER STEAM ENGINES," upon the condition (amongst others)
that I, the said James Griffiths, my executors or administrators, by an instru-
ment in writing under my, 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said James Griffiths, 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, that is to say:-
My Invention consists of a new or improved brake for colliery and other
steam engines, constructed in the manner herein-after described, and illus-
trated in the accompanying Drawing.
Figure 1 represents my Invention in side elevation; and Figure 2 repre-
sents the same in plan. In the ordinary brake for colliery engines, a piece of
wood or other substance is made to press upon a pulley fixed on the main
shaft of the engine or on the drum shaft.
My Invention consists of a semi-cylindrical or nearly semi-cylindrical piece
of wood a, or of two such picces a, b, made to press upon the edge of the
toothed wheel c, instead of upon a smooth pulley. The said pieces of wood

page_text: a, b, are jointed to the bracket d at e, f; the said pieces of wood a, b, are
tightened upon the wheel c by the arm or lever g; the said arm or lever g is
connected with a by the link h, and with b by the link k. By raising the arm
or lever g, the part a is pulled downwards and the part upwards, and the
said parts a, b, are thus made to grasp the toothed wheel c, and arrest its
motion. The toothed wheel c is situated on the drum shaft of colliery engines,
and is the wheel by which motion is transmitted from the axis of the fly wheel
to the said drum. I is a winch or handle on the axis m; n is a chain, fixed at
one end to the arm or lever g, and at the other to the axis m. By turning the
winch or handle I, the chain n may be coiled on the axis m, and the arm or
lever raised. By the raising of the said arm or lever g, the semi-circles a
and are made to press on the wheel c, as already described. A pall and
ratchet o retain the axis m in the position in which it has been placed, and
maintain the pressure on the wheel c.
Although my Invention is specially applicable to colliery engines, yet it may
be applied to steam engines in general.
Having now described the nature of my said Invention, and the manner of
carrying the same into effect, I wish it to be understood that I do not limit
myself to the precise details herein described and represented, as the same
may be varied without departing from the nature of my said Invention; but
I claim as my Invention the new or improved brake for colliery and other
.steam engines, constructed as hercin-before described, and represented in the
accompanying Drawing; that is to say, a brake in which pressure is exercised
upon a toothed wheel, as described, instead of a smooth pulley, as usually
practised.
In witness whereof, I, the said James Griffiths, have hereunto set my
hand and seal, this Nineteenth day of August, in the year of our Lord
One thousand eight hundred and fifty-six.
o Witness,
GEORGE SHAW.
JAMES GRIFFITHS. (L.S.)