IMPROVEMENTS IN PNEUMATIC HAMMERS OR STAMP- MILLS FOR CRUSHING ORES AND FOR OTHER PURPOSES "
Year: 1883

page_text: LETTERS PATENT to Charles Sholl, of Tower Chambers, in the City of, London,
for an Invention of "IMPROVEMENTS IN PNEUMATIC HAMMERS OR STAMP-
MILLS FOR CRUSHING ORES AND FOR OTHER PURPOSES "
PROVISIONAL SPECIFICATION left by the said Charles Sholl at the Office
of the Commissioners of Patents on the 7th September 1883.
CHARLES SHOLL, of Tower Chambers in the City of London
If
IMPROVEMENTS
IN PNEUMATIC HAMMERS OR STAMP-MILLS FOR CRUSHING ORES AND FOR OTHER
PURPOSES
"
My invention rolates chiefly to pneumatic hammers or stamp-mills of the class
described in the Specification of former Letters Patent dated 13th July A.D. 1875
No. 2524; that is to say, stamp-mills in which atmospheric air is employed to
form a cushion for the hammer or stamp.
The said invention comprises various improvements and novel features of
construction as hereinafter set forth.
In carrying my said invention into practice I make the pneumatic cylinder and
the stamp or hammer separately, and connect them by means of flauges and bolts ;
and I make the pneumatic cylinder either in one piece or in two pieces which are
connected at, or near, the centre of the cylinder by means of flanges and bolts.
The bottom of the cylinder is cast in one piece with the body thereof to prevent
the escape of air under compression which might otherwise occur by leakage
during the reciprocation of the piston.
I also provide the said cylinder with a lining composed of a metallic alloy to
counteract the effect of the heat evolved by the constant compression of air in the
cylinder by the reciprocation of the piston. This lining is either flanged and
connected by the bolts at the junction of the top and bottom portions of the
cylinder, or it is made in one piece and, held in place by a cover bolted to the said
cylinder. I use for this lining any metallic alloy which is durable under the
influence of friction and which is a bad conductor of heat.
Instead of the orifices in the cylinder for the ingress and egress of air as
described in the said former specification I form two long slots in the pneumatic

page_text: cylinder, through which slots passes a transverse pin; and upon this pin is pivotted
what I term a "plug" pneumatic piston furnished with rings composed of a
metallic alloy. This piston is reciprocated either by a bifurcated connecting rod,
or by two connecting rods coupled at one end to the said pin and at the other
end to the crank of the main driving shaft of the stamp-mill. The said slots
are made long enough to admit air beneath the piston when the same is at the
top of its stroke, and above the said piston when it is at the bottom of its stroke.
These slots are more advantageous than the said small holes or orifices, for the
purpose above stated.
In order to keep the said cylinder cool I employ a perforated pipe (which is
preferably circular) in connection with a suitable apparatus for supplying water
thereto. Two perforated branch pipes lead from the said pipe and are arranged in
recesses in the guides of the said cylinder so that a constant stream of cold water
can be made to flow over the outside surface of the pneumatic cylinder and
eventually escape into the coffer where the material is crushed.
When these stamp-mills are employed in the Colonies or other parts of the globe
where no means are at hand for re-boring the pneumatic cylinder, I provide the
following substitute for the cushion of air, that is to say, I fix a helical spring
to the top of the pneumatic piston so that as the said piston approaches the
top of its stroke it compresses the said spring. A similar spring may, if desired,
be fitted to the bottom of the piston. These springs can be readily replaced when
required.
I sometimes use an inverted steam cylinder of any desirable description, which
cylinder is provided with rods depending from a "bow," or other contrivance
reciprocated by the said engine and coupled on either side to the pin which passes
through the piston as above described. I am thus enabled to reciprocate the piston
by "direct action" and to dispense with belts and a separate motor.
In some cases I form a hollow space or tube through the centre of the pneumatic
cylinder for the purpose of feeding the ore in such a manner that it falls into
the centre of an annular shoe on the hammer or stamp. This shoe will wear more
evenly than those ordinarily employed and the crushed ore will be equally
distributed to the screens or grates. In this case I employ an annular piston
instead of a piston of the ordinary type.
Although I have described my invention particularly as applicable to a stamp-
mill for crushing ore, it is obvious that I can apply it to hammers or stamp-mills
for other purposes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Sholl in the Patent Office on the 7th March 1884.
CHARLES SHOLL, of Tower Chambers, in the City of London,
'IMPROVEMENTS
IN PNEUMATIC HAMMERS OR STAMP-MILLS FOR CRUSHING ORES, AND FOR OTHER
PURPOSES
"
'
My invention relates chiefly to pneumatic hammers or stamp-mills of the class
described in the Specification of former Letters Patent dated 13th July, A.D. 1875,
N° 2524, that is to say, stamp-mills in which atmospheric air is employed as a
cushion for the hammer or stamp as hereinafter specified.
The said invention comprises various improvements and novel features of
construction as hereinafter set forth..
In the accompanying drawing-
Figure 1 is a vertical central section of my improved stamp-mill, with some of
the parts shewn in elevation.
Figure as a section on the line x, x, Figure 1.
Figure 3 is a horizontal section of the pneumatic cylinder and its guides.
Figure 4 is a vertical central, section of another form or modification of my
improved stamp-mill, with some of the parts shewn in elevation, and
Figure 5 is a horizontal section of the pneumatic cylinder shewing the cross-
head in elevation
Like letters indicate corresponding parts throughout the drawing
In Figures 1 and 2, A indicates the pneumatic cylinder and B the stamp
or hammer. These parts are preferably made separately for convenience in
transportation and in supplying duplicates of these parts of the apparatus. And
the said parts ore rigidly united by means of the flanges a, a¹ and bolts a³ as
shown in Figure 1. The cylinder A is, for the same purpose, made in two parts
which are equal, or nearly equal, in length and are rigidly connected by means of
the flanges b, b' and suitable bolts, and the top or end of the cylinder is cast in
one piece with the body thereof. I also provide the said cylinder with a lining A¹
composed of a metallic alloy which will counteract the effect of the heat evolved
by the constant compression of air in the cylinder by the reciprocating action
of the piston. This lining A' is sometimes made in two pieces each provided with
a flange, and the said flanges are held between the flanges b, b' of the top and
bottom portions of the cylinder, as shown in Figure 2. In other cases the said
lining is made in one piece, which is provided with a flange and is held in place
by a cover C bolted to the cylinder A as shown in Figure 4.
I use for this lining any metallic alloy which is durable and will diminish
the friction between the cylinder and piston, and which is a bad conductor
of heat.
"
Instead of admitting air to the cylinder, to serve as a cushion, by means of the
orifices or apertures as described in the said former Specification, I make the
cylinder with two longitudinal slots D, through which passes a transverse pin E..
Upon this pin is pivotted what I term a plug" pneumatic piston F furnished
with rings fof a metallic alloy. This piston is reciprocated either by a bifurcated
connecting rod G, as shown in Figures 1 and 2, or by two connecting rods G¹, G³,
as shown in Figure 4, the said rod or rods being coupled at one end to the said
pin E or to the pins E' E' (Figure 4) and at the other end to the crank of the
main driving shaft H. The slots D are made of such length that they will admit
air between the piston and either end of the cylinder, but in the up-stroke of the
.

page_text: piston, the upper ends of the said slots will be closed thereby, and in the down-
stroke of the piston, the lower ends of the said slots will be closed thereby, so that
the air admitted above or below the piston will be compressed, and act as a cushion.
The said slots are more advantageous for this purpose than the orifices or apertures
described in the said former specification.
In addition to the lining A¹ I provide the following means for keeping the
cylinder A cool and for supplying water to moisten the ore or other material to be
crushed, that is to say, a circular perforated pipe I is placed above the cup J at
the upper end of the coffer K. This pipe is connected with a suitable water-
supply. Two perforated branch-pipes I extend from the pipe I and are arranged
between recesses or grooves in the guides i and corresponding recesses or grooves
in the exterior of the cylinder, as shown in Figures 2 and 3. By these means
a constant stream of cold water can be made to flow over the outer surface of the
pneumatic cylinder and eventually escape into the coffer K where the ore or other
material is crushed.
In Figure 4 I have shewn a modification of my invention wherein I make the
cylinder A and stamp B with a central tube M through which the ore can be fed
from a hopper N in such a manner that it falls through the centre of an annular
shoe B¹ on the hammer-or stamp B into the coffer K. When the apparatus is
thus constructed, the shoe B¹ will wear more evenly or uniformly than those
ordinarily employed and the crushed ore or other material will be equally
distributed to the screens or grates. In the apparatus shewn in Figure 4. the
cylinder and stamp are made in one piece and an annular piston F1 must be
employed instead of a piston of the ordinary type.
When my improved stamp-mill is to be employed in the Colonies or other parts
of the globe where no means are readily attainable for re-boring the pneumatic
cylinder, I provide the following substitute for the air-cushion above described,
that is to say, I fix a spring L, which may be an ordinary buffer-spring, to the
top of the piston F, as shown in Figures 1 and 2, so that as the said piston
approaches the top of its stroke it compresses the said spring. A similar spring
may, if desired, be fitted to the bottom of the piston. These springs can be readily
replaced when required.
I sometimes use an inverted steam-cylinder of any desirable description, the
piston of which is connected in any suitable manner to the piston F. I am thus
enabled to reciprocate the piston by direct action as described in the said former
Specification and to dispense with belts and a separate motor.
Having thus fully described my said invention and the manner of performing
the same I wish it understood that although I have above referred particularly to
a stamp-mill for crushing ore, I can apply my said invention to hammers or stamp-
mills for other purposes and I Claim:
First. The stamp or hammer and the pneumatic cylinder made separately and
rigidly united, substantially as, and for the purpose, set forth.
Second. The pneumatic cylinder made in two parts which are rigidly united,
substantially as, and for the purpose, set forth.
Third. The combination, with the pneumatic cylinder, of the lining composed of
a metallic alloy, substantially as, and for the purpose, set forth.
Fourth. In the working of my improved hammer or stamp-mill, the admission
of air to the cylinder, to serve as a cushion, by means of the longitudinal slots,
substantially as set forth.
Fifth. The perforated water-pipe arranged above the coffer and having the
perforated branch-pipes extending therefrom between the cylinder and its guides,
substantially as, and for the purpose, set forth.
Sixth. The employment of a spring as a substitute for the air cushion,
substantially as, and for the purpose, set forth.
Seventh. The construction of the pneumatic cylinder and the hammer or stamp
with the central tube, substantially as, and for the purpose, set forth.

page_text: Eighth The improved pneumatic hammer or stamp-mill consisting of the parts
constructed and combined substantially as described with reference to either
of the modifications shewn in the accompanying drawing, and operating as, and
for, the purpose, set forth.
In witness whereof I the said Charles Sholl have hereunto set my hand and
seal this Fifth day of March in the year of our Lord One thousand eight hundred
and eighty four.
CHARLES: SHOLL (L.S.)