IMPROVEMENTS IN THE WORKING AND CONSTRUCTION OF POWER HAMMERS. IN WHICH THE RECIPROCATING MOTION IS TRANSMITTED THROUGH THE AGENCY OF AN ELASTIC FLUID, AND IN APPARATUS USED IN CONNECTION THEREWITH."
Year: 1877

page_text: LETTERS PATENT to David Davy, of Park Iron Works, Sheffield, in the County
of York, Engineer, for the Invention of "IMPROVEMENTS IN THE WORKING
AND CONSTRUCTION OF POWER HAMMERS. IN WHICH THE RECIPROCATING
MOTION IS TRANSMITTED THROUGH THE AGENCY OF AN ELASTIC FLUID, AND
IN APPARATUS USED IN CONNECTION THEREWITH."
PROVISIONAL SPECIFICATION left by the said David Davy at the Office
of the Commissioners of Patents on the 9th June 1877.
DAVID DAVY, of Park Iron Works, Sheffield, in the County of York, Engineer.
"IMPROVEMENTS IN THE WORKING AND CONSTRUCTION OF POWER, HAMMERS IN
WHICH THE RECIPROCATING MOTION IS TRANSMITTED THROUGH THE AGENCY OF, AN
ELASTIC FLUID, AND IN APPARATUS USED IN CONNECTION THEREWITH."
.:)
My Invention relates to power hammers of that kind in which the hammer head
is actuated from a crank, eccentric, or other motive mechanism through the medium
of an elastic fluid contained in a cylinder, which is made to reciprocate by said
crank, eccentric, or other mechanism, the hammer head being attached to a piston
within the cylinder. In such hammers the pressure above and beneath the piston
is equal when the hammer is at rest, but as the cylinder reciprocates the piston
and hammer head, which also reciprocate, are by their momentum caused to make
a longer stroke than that of the cylinder, due to the throw of the crank or eccentric
alone, and the fluid is consequently compressed on one side of the piston, and
rarefied on the other. The air or other elastic fluid being admitted to the cylinder
at atmospheric pressure the compression required to raise the hammer and accelerate
its fall must necessarily be effected within the cylinder itself, which involves the
use of a cylinder of large capacity, and renders the construction of a powerful
hammer on this principle almost impracticable.
My Invention has for its object to increase the effectiveness of the blow, and at
same time permit of a comparatively small cylinder being used, thus rendering the
machine less cumbrous to construct, and it consists in the employment of air, steam,

page_text: or other suitable elastic fluid introduced into the cylinder at a higher pressure than
that of the atmosphere, the pressure of the fluid being increased according to the
power required.
The Invention also consists in certain improvements in the cylinder and apparatus
connected therewith for the supplying the air, steam, or other elastic fluid thereto,
and governing the pressure therein, and in apparatus for maintaining a reserve of
the air or other elastic fluid (except steam) at a constant pressure to provide against
loss by leakage or otherwise."
In carrying out my Invention I introduce into the reciprocating chamber steam,
compressed air, or other elastic fluid at a higher pressure than that of the atmosphere,
and for this purpose I provide pipes, suitably arranged, and connected to the cylinder
to permit of it reciprocating.
In one arrangement" the pipes are fixed parallel to the line of motion of the
cylinder, and pass through stuffing boxes in the ends of chambers formed on
the outside of the cylinder, and communicating with the interior thereof by one or
more of a series of holes closed by screw plug at will to regulate the amount of
extra compression in the cylinder, due to the momentum of the hammer and piston.
In this arrangement the stuffing boxes move with the cylinder, and slide up and
down the pipes; but in lieu thereof I may employ pipes having swivel joints, or
having sufficient elasticity to allow of the movement of the cylinder without
sliding swivel or other joints.
The office and action of the clastic fluid at a higher pressure than that of the
atmosphere is similar to that above described, that is to say, when the hammer is
Then at work the
at rest the pressure is equal on both sides of the piston; and when at
fluid on one side of the piston is allowed to expand slightly, whilst that on the
otlier side is raised to a still higher pressure.
.:
To prevent excess of pressure I may provide relief, channels in the sides of the
cylinder, which will allow the fluid to pass from one side of the piston to the other
when it passes beyond 'n'given point.
4 i,
For compressing the air or other elastic fluid (except steam) I employ a pump,
in which the inlet valve is so arranged as to draw the air through cold water to
cool and cleanse it, and in order to maintain a constant pressure I employ an accu-
mulator suitably loaded.
To prevent a further supply of air without stopping the pump when the accumu-
lator is
sufficiently charged the accumulator ram, when it has risen to a given
height, is by suitable connections made to raise the inlet valve of the pump off its
seat, so that the pump will cease to supply air until the accumulator ram has
descended sufficiently to allow the inlet valve to close again.
$ 1
When steam is employed provision would be made to get rid of the water of
ondensation

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David Davy in the Great Seal Patent Office: on the 8th December
1877.
66
DAVID DAVY, of Park Iron Works, Sheffield, in the County of York, Engineer.
IMPROVEMENTS IN THE WORKING AND CONSTRUCTION OF POWER HAMMERS IN
WHICH THE RECIPROCATING MOTION IS TRANSMITTED THROUGH THE AGENCY OF AN
ELASTIC FLUID, AND IN APPARATUS USED IN CONNECTION THEREWITH.”
My Invention relates to power hammers of that kind in which the hammer head
is actuated from a crank, eccentric, or other motive mechanism through the medium.
of an elastic fluid contained in a cylinder which is interposed between the hammer
and its actuating shaft, and, which is made to reciprocate by said crank, eccentric,
or other mechanism, the hammer head being attached to a piston within the
cylinder. In such hammers the pressure above and beneath the piston is equal
when the hammer is at rest, but as the cylinder reciprocates the piston and hammer
head, which also reciprocate, are by their momentum caused to make a longer.
stroke than that of the cylinder, which is due to the throw of the crank or eccentric
alone, and the fluid is consequently compressed on one side of the piston, and
rarefied on the other. The air or other elastic fluid having heen hitherto admitted to
the cylinder at atmospheric pressure the compression beneath and above the piston
required to raise the hammer, and to accelerate its fall, has necessarily been effected.
within the cylinder itself, thereby involving the use of a cylinder of large capacity,.
and consequently rendering the construction of a powerful hammer on this prin-
ciple almost impracticable.
My Invention has for its object to enable the effectiveness of the blow to be
increased, and yet a comparatively small cylinder to be used, so that the machine.
is less cumbrous to construct, and it consists in the employment of air, steam, or
other suitable elastic fluid introduced into the cylinder at a higher pressure than
that of the atmosphere, the pressure of the fluid being increased according to the.
power required.
The Invention also consists in certain improvements in the cylinder and apparatus
connected therewith, and in apparatus for maintaining a reserve of the air or other.
elastic fluid (except steam) at a constant pressure to provide against loss by leakage
or otherwise.
In carrying out my Invention I introduce into the reciprocating chamber steam,
compressed air, or other elastic fluid at a higher pressure than that of the atmosphere,
and for this purpose I provide pipes suitably arranged and connected to the cylinder
to permit it to reciprocate.
In one arrangement the pipes are fixed parallel to the line of motion of the
cylinder, and pass through stuffing boxes in the ends of chambers formed on the
outside of the cylinder, and communicating with the interior thereof by one or
more of a series of holes, which may be closed by screw plugs at will to regulate
the amount of extra compression in the cylinder, due to the momentum of the
hammer and piston. In this arrangement the stuffing boxes move with the cylinder,
and slide up and down the pipes; but in lieu thereof I may employ pipes having
swivel joints, or having sufficient elasticity to allow of the movement of the cylinder
without sliding, swivel, or other joints.
The office and action of the elastic fluid at a higher pressure than that of the
atmosphere is similar to that above described, that is to say, when the hammer is
at rest the pressure is equal on both sides of the piston, and when at work the
fluid on one side of the piston is allowed to expand slightly, whilst that on the
other side is raised to a still higher pressure.
To prevent excess of pressure I may provide relief channels in the sides. of the
cylinder, which will allow the fluid to pass from one side of the piston to the other,.
when it passes beyond a given point.

page_text: For compressing the air or other elastic fluid (except steam) I employ a pump,
in which the inlet is so arranged that the air is cooled and cleansed by being drawn
through cold water, and in order to maintain a constant pressure I employ an accu-
mulator suitably loaded.
To prevent a further supply of air to the accumulator when sufficiently charged
without stopping the pump the accumulator ram, when it has risen to a given
height, is by suitable connections made to raise the inlet or suction valve of the
pump off its seat, so that the pump will cease to supply air until the accumulator
ram has descended sufficiently to allow the suction valve to close again."
When steam is employed it will be generated in the ordinary way, and no "com-
pression pump will be necessary. In this case it will be requisite to make provision
matting wid of the seater of condensation.
Figure 1 represents a front elevation of my improved power hammer, the cylinder
being shown in section; Figure 2 represents a vertical section of the same on line
1-1, Figure 1; and Figure 3, a horizontal section on line 2-2, Figure 1.
Figure 4 represents the application of a flexible pipe for conveying the com-
pressed air, steam, or other elastic fluid employed to the cylinder.
Figure 5 represents an elevation, and Figure 6 a vertical section on line 3-3,
Figure 5, of the air-compressing pump and the accumulator for maintaining the
reserve of air under pressure, the two latter Figures being drawn to a larger
scale.
In Figures 1 and 2 A is the hammer head attached to the rod of a piston B,
which works in a cylinder C that is operated through a connecting rod D by a
crank shaft E in the ordinary manner. The steam, air, or other elastic fluid under
pressure is introduced by one or two pipes F provided with stop-cocks.
In Figures 1 and 2 I have shown one method of connecting the pipes to the
cylinder, but do not limit myself thereto, as the mode of attachment may be varied
as before mentioned.
The portions F¹ of the pipes are parallel to the cylinder and pass through stuffing
boxes on the ends of the two chambers G on the outside of the cylinder. These
chambers cominunicate with the cylinder by one or more holes H; these holes
may be fitted with screw plugs H₁, by which those not in use are closed in order
to regulate the extra compression, but the screw plugs may be dispensed with, and
two or more holes provided for the admission of compressed air situated imme-
diately above and below the piston when in a central position; but I do not limit
myself to this arrangement, as the position of the holes may be varied in hammers
of different sizes. I are longitudinal relief channels formed in the inside of the
cylinder for a certain distance from the top end to allow the fluid to pass from the
upper to the lower side of the piston, when the latter passes beyond the end of said
channel.
In Figures 5 and 6, K. is the pump plunger worked from an eccentric or crank
on a shaft L, or otherwise; it is fitted to work in a barrel M, provided with suction
and delivery valves N, O, and the whole contained in a closed chamber or cistern P
filled with water above the level of an opening at one side, with a cup Q
attached, forming a sort of syphon trap, the cup also containing water, through
which the air must pass to the pump; R is the accumulator ram, and R¹ its
cylinder, which may be partly immersed in the water in chamber P to keep cool
the compressed air supplied by the pump through the delivery valve O and delivery
pipe O¹ to the accumulator; S is a rock shaft mounted in the cistern P, and pro-
vided with a cam or lever S¹ that takes under and raises the suction valve N when
the shaft is oscillated. One end of the shaft is prolonged through the side of the
cistern P, and provided with a lever arm and connecting rod not shown, but indi-
cated by the dotted lines T, the connecting rod terminating in such a form as to be
acted on by the accumulator ram R, or the cross bar R, by which it is loaded

page_text: when it rises to a certain height, so as to oscillate shaft S, and cause the suction
valve to be raised off its seat to prevent the further supply of compressed air to
the accumulator without stopping the pump.
Having described the nature of my Invention, and the manner of performing
the same, I declare that what I claim as my Invention to be protected by the herein-
before in part recited Letters Patent is,―
1st. The application and employment in the cylinder of a power hammer (of
the kind herein shown and described) of air, steam, or other elastic fluid at a
pressure (when the hammer is at rest) higher than that of the atmosphere, as and
for the purpose specified.
2nd. In a power hammer working with steam, compressed air, or other elastic
fluid as described, the combination with the working cylinder of the chambers G
communicating with the cylinder by holes H, and having flexible or jointed pipes
attached, substantially as shown and described for the purpose specified.
3rd. In a power hammer working with compressed air, steam, or other elastic
fluid, as described, the combination with the reciprocating cylinder and the
chambers communicating therewith, and provided with stuffing boxes, of the
parallel admission pipes for the stuffing boxes to slide upon, substantially as and
for the purpose specified.
4th. In a power hammer working with steam, compressed air, or other elastic
fluid, as described, the combination with the reciprocating cylinder and its piston
of the relief channels in the cylinder, substantially as and for a purpose specified.
5th. The combination in a power hammer working with steam, compressed air,
or other elastic fluid, as described, of the several improvements described and shown
in Figures 1 and 2 of the Drawings.
6th. In an air-compressing pump, arranging the air inlet so that the air must
be drawn through water, in order to pass to the pump, substantially as and for the
purpose specified.
7th. The combination with an air-compressing pump and accumulator for com-
pressed air of a device operated by the accumulator, ram, or other part in connection
therewith, and acting on the suction valve of the pump, substantially as and for the
purpose specified.
In witness whereof, I, the said David Davy, have hereunto set my hand and
seal, this Sixth day of December, in the year of our Lord One thousand
eight hundred and seventy-seven.
DAVID DAVY. (L.S.)