Improvements in Pneumatic Hammers.
Year: 1891

page_text: Date of Application, 11th Mar., 1891
Complete Specification Left, 9th Dec., 1891-Accepted, 9th Jan.,
1892
PROVISIONAL SPECIFICATION.
Improvements in Pneumatic Hammers.
We JAMES FREDERICK LAKE, of Countess Road, Sheffield in the County of
York, Engineer, and GEORGE HENRY CRAWSHAW, of Storth House, Holmesfield
in the County of Derby, Gentleman, do hereby declare the nature of our invention
to be as follows :-
This invention has for its object to simplify the valve mechanism used for
regulating the blow of the hammer; and it refers more particularly to pneumatic
hammers in which there is a vertically moving air cylinder, the piston rod being
attached to the hammer head or tup.
Ilitherto it has been necessary to use two or more valves, but where one valve
has been proposed to be used, it has been distinctly understood that it was placed
in the centre of the cylinder, the object being to enable it to admit air on each side
of the piston i.e. above and below.
We propose to use only one valve, and to communicate through it only with the
top side of the piston, the lower half of the cylinder being without a valve, but a
free port is made into the cylinder about its centre to allow the air free egress and
entrance.
The valve is preferably cylindrical and has a valve rod of large diameter, which
projects outwards, and which can be pressed inwards by a wedge or its equivalent
worked by the attendant.
The valve rod is hollow, closed at both ends and provided with openings into the
interior made near each end for the passage of air, so that when the valve is moved
from its seat, the compressed air inside the cylinder can escape, in any required
quantity, as the holes above described are more or less exposed; this action
regulates the force of the blow.
The valve is kept up to its seating by the pressure of a coiled spring placed at
the back, and we prefer to fix the valve horizontally.
The valve as described communicates with the cylinder above the travel of the
piston, and an opening or free air port made halfway down the cylinder or
thereabouts communicates with the lower portion.
By this arrangement of valve opening into the upper part of the cylinder, we
can permit the escape of air so as, to regulate the cushioning power from the
maximum to the minimum according to the blow required.
Dated the 10th day of March 1891.
ROBT. F. DRURY, Fel. Inst. P.A.,
Bank Buildings, George Street, Sheffield, Agent for Applicants.
COMPLETE SPECIFICATION.
Improvements in Pneumatic Hammers.
We JAMES FREDERICK LAKE, of Countess Road, Sheffield in the County of
York, Engineer, and GEORGE HENRY CRAWSHAW, of Storth House, Holmesfield
in the County of Derby, Gentleman, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
This invention has for its object to simplify the valve mechanism ordinarily used
in pneumatic hammers for regulating the blow of the hammer, and it refers more
particularly to pneumatic hammers in which there is a vertically moving air
cylinder, with the outer end of the piston rod attached to the hammer or tup.

page_text: Hitherto in such hammers it has been usual to use two or more valves, or when
one valve has been proposed to be used, it has been arranged in the centre or there-
abouts of the cylinder, so that it might carry out the intended object of admitting
air on each side of the piston alternately, and of permitting a portion to escape in
a similar manner.
I carry out my invention in the manner illustrated in the accompanying drawings
in which,
Fig. 1, represents a partly sectional view of the top of moving cylinder, with
the valve, and operating incline or wedge.
Fig. 2, section of valve.
Fig. 3, section of valve of original construction.
Similar letters refer to similar parts in any of the figures.
In carrying out the invention I use by preference only one valve A, which
communicates only with the space in the top part of the cylinder marked B, and
above the travel of the piston, the lower half of the cylinder being without a
valve, but a free or open port C, is made into the cylinder at or near the centre to
allow the free entrance and escape of air.
The valve A, is preferably cylindrical and its shank is provided with one or more
outside longitudinal grooves or air passages D, which terminate below the
underside of the valve seating.
The valve is held with elastic pressure against the seating by the reaction of a
coiled (or other form) of spring E, bearing against the head of the valve, and the
apertures F, permit the passage of air into and out of the cylinder.
The valve is opened to permit the passage of air by the action of a tapered slide
or wedge piece G, which when moved forward by the attendant presses the valve
from its seat and allows the compressed air in the cylinder to escape in a large or
small volume, as the ends of the grooves D, are more or less exposed.
A modification in the construction of the valve, being the one described in the
Provisional Specification and shown in Fig. 3, has its shank made hollow with
ports H, at each end for the passage of air into or out of the cylinder, the other
parts of the valve are similar to those first described and its action is the same.
By this arrangement of a valve opening into the upper part B, of the moving
cylinder of pneumatic hammers, in combination with a centrally placed open port C,
as described, the escape of compressed air, and the consequent variation of the
cushioning effect, can be so completely and effectively regulated and controlled
that the blow of the hammer can be changed from minimum to the maximum of
power, or regulated to any desired intermediate power.
Having now particularly described my invention and shown how it may be carried
into effect, I wish to be understood that although I have described a valve, the
construction of which is very suitable and effective for the purpose named, I do
not bind myself to that particular construction, but what I claim is :-
Constructing the (vertically moving) air cylinder of pneumatic hammers with an
air escape valve for the purpose specified capable of being regulated at will by the
attendant while the hammer is at work, in combination with an open port centrally
arranged in the cylinder, substantially as set forth.
Dated the 7th day of December 1891
ROBT. F. DRURY,
Bank Buildings, George Street, Sheffield, Agent for Applicants.