Improvements in Fluid Pressure Hammers and like Tools or Machines.
Year: 1897

page_text: Date of Application, 18th June, 1897-Accepted, 24th July, 1897
COMPLETE SPECIFICATION.
Improvements in Fluid Pressure Hammers and like Tools or
Machines.
I, CHARLES HARRIS JOHNSON, of Haas Building, Third Street, Springfield,
Sangamon County, Illinois, United States of America, engineer, do hereby
declare the nature of my invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
My invention relates particularly to machines adapted to be operated by fluid
pressure, and especially to that class of machines that are known in the art as
portable pneumatic hammers.
The object of my invention is to provide a simple, economical and efficient
fluid pressure hammer: and the invention consists in the features, combinations
and details of construction hereinafter described and claimed.
In the accompanying drawings, Figure 1 is a central, longitudinal, sectional
elevation of a pneumatic hammer fitted with my improvements and with the
movable parts arranged at one limit of their motion and Fig. 2 a similar view
of the movable parts arranged at the opposite limit of their motion.
severe
In the art to which this invention relates, and in fact in the art generally, it is
well known that where a reciprocating piston is used there is a
jar incident to the sudden stoppage of the piston and its starting on its opposite
movement. Especially is this true when tools of this class are made sufficiently
overcome this objection,
powerful for the operation of riveting. In order to
various tools have been devised having counterpoises and balances, and made so
heavy as to be no longer portable in the true sense of the word. To overcome
these objections and provide a tool of such construction that it will automatically
establish a balance or equipoise between the parts and prevent or absorb shocks
or jars is the principal object of my invention.
In describing and illustrating my improvements, I prefer to describe and
illustrate them in connection with what is known as a portable pneumatic
hammer. I do this for the sake of brevity and clearness; but I wish it to be
distinctly understood that I do not desire to be limited strictly to this class of
mechanism, as my improvements are capable of being adapted and used in various
other mechanisms, by slight modifications and arrangements of parts which the
skilled mechanic is capable of performing, without departing from the spirit of
the invention.
In constructing a pneumatic hammer in accordance with my improvements,
I make what I term a cylindrical casing A, of the desired size, shape and strength
to hold the operative mechanisms. This casing is preferably provided with a
handle portion a, that carries the inlet valve B and operating lever b. The casing
portion is further provided with a cylindrical chamber a¹, in which is mounted
at one end a cylindrical holder. C that carries the operating tool C¹-in this in-
stance a rivet set. The tool-holder is provided with an annular flange
abuts against the end of the casing proper and is held in place by means of a cap D
c that

page_text: 1
and a helical spring d, which is inserted between the cap and the annular
shoulder the helical spring permitting of a movement of the holder when
occasion requires.
To operate on the tool and maintain balance of the parts or prevent shock or
jar, I make what I term a reciprocating cylinder E and mount it in a cylindrical
chamber of the casing. The reciprocating cylinder and the casing are so arranged
and constructed as to provide an annular chamber e between such parts--such
annular chamber being preferably at all times in communication with the inlet
passage el that leads from the inlet valve. Mounted in the reciprocating cylinder
is a piston hammer G provided at one end with a head portion and so arranged
as to provide an annular chamber between it and the auxiliary reciprocating
cylinder. The auxiliary reciprocating cylinder is also provided with passages g
that afford communication between the chambers e and g', so that fluid pressure at
the proper time may pass from the source of the fluid pressure supply to the
interior annular chamber.
In order to operate the piston hammer in one of its directions and the reciproca-
ting cylinder in the opposite direction, I provide the piston hammer with a
longitudinal passage or opening G which opens into a space at one end between
it and the extreme end of the reciprocating cylinder; and at or near the other end
are provided transverse passages g³ that allow it to alternately communicate with
the annular chamber and the casing chamber a. The casing chamber a¹ is
provided with exhaust passages a³ through which the fluid pressure is ultimately
exhausted into the open air.
Having thus described the construction of parts, I will now proceed to describe
the operation of the mechanism. Assuming the parts to be in the position shown
in Fig. 2, the lever is depressed, the inlet valve open, and fluid pressure flows
into the annular chamber é, acts on the forward part of the shoulder c³ of the
reciprocating cylinder and forces it inward to the position shown in Fig. 1, 30
as to contact the tool-holder and thereby deliver a blow on the tool. At the
same time a certain amount of pressure flows through the passages into the
inner, annular chamber and acts against the head of the piston hammer to
force the same back to the position shown in Fig. 1. This equalizes in a measure
the blow delivered on the tool, and each acts to balance the other movement, so
that there is very little tendency to recoil. The fluid pressure then passes in
through the passages g³ and G₁ into the chamber e³ of the reciprocating cylinder
between the end of the reciprocating cylinder and the piston hammer, so that it
may act in an expansive manner upon a larger area and against the direct pressure
of the smaller surface and force the piston hammer in-as shown in Fig. 2-to
deliver a blow direct to the tool. At the same time the fluid pressure acts to force
the reciprocating cylinder outwardly or backwardly to the piston shown in Fig. 2,
which serves to act as a balance to the inward thrust and prevent or minimize the
recoil. These operations are repeated and continued as often as desired and as
rapidly as desired, due to the amount of and length of time that fluid pressure is
furnished. The reciprocating cylinder may be provided with a second set of
transverse openings K, which act to more quickly exhaust the pressure and permit
the reverse movement of the piston to take place with greater rapidity.
The principal advantage due to my improvement is that I provide a tool of
minimum lightness, containing only enough of metal to withstand the strains
incident to use, and which minimizes the amount of shock, jar and recoil due to
the use of this class of tools.
While I have described my invention with more or less minuteness as regards
details, and as being embodied in certain precise forms and available to certain
specified means, I do not desire to be limited thereto unduly, or any more than is
pointed out in the claims. On the contrary, I contemplate all proper uses,
changes in form, construction and arrangement the omission of immaterial
eléments and the substitution of equivalents, as circumstances may suggest or
necessity render expedient.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. A valveless portable pneumatic hammer, in which there is combined a cas-
ing provided with inlet and exhaust openings, an operating tool in one end thereof,
a reciprocating piston in such casing arranged to contact the tool at one limit of
its stroke, and provided with a fluid pressure channel whereby fluid pressure is
admitted from one side of the piston to the other to reciprocate and operate the
same, substantially as described.
2. In a machine of the class described, a casing provided with a fluid pressure
chamber and inlet and exhaust openings, an operating tool in one end thereof,
a reciprocating piston hammer in the casing arranged to contact the operating
tool at one limit of its stroke and divide the pressure chamber into two chambers,
and means whereby fluid pressure is admitted constantly to one side of the piston
and through the piston is alternately admitted to and exhausted from the other
side of the piston to reciprocate the same and operate the parts, substantially as
described.
3. In mechanisms of the class described, the combination of a casing provided
with a cylindrical chamber, and two reciprocating portions mounted therein so
as to have opposite motions at substantially the same time, substantially as
described.
4. In mechanisms of the class described, the combination of a casing provided
with a cyclindrical chamber, a reciprocating cylinder mounted therein, a reciproca-
ting piston mounted in the reciprocating cylinder, and means for furnishing fluid
pressure to the parts so as to move them in opposite directions, substantially as
described.
5. In mechanisms of the class described, the combination of a casing provided
with a cylindrical chamber, a reciprocating cylinder mounted therein and having
one end closed, a reciprocating piston mounted in the open end of the reciproca-
ting cylinder, and means for furnishing fluid pressure to the parts to move them in
opposite directions during substantially or nearly the same period of time,
substantially as described.
6. In mechanisms of the class described, the combination of a casing provided
with a cylindrical chamber, a reciprocating cylinder mounted therein having one
end closed and providing an annular fluid pressure chamber between it and the
casing to drive it in one direction, and a reciprocating piston mounted in the open
end of said cylinder so as to provide a second annular pressure chamber between'
it and the cylinder and provided with a longitudinal passage there through to
furnish communication with the annular chamber and the space between the
inner end of the piston and cylinder so as to furnish fluid pressure to drive the
piston in one and the cylinder in an opposite direction, substantially as described.
7. In mechanisms of the class described, the combination of a casing provided
with a longitudinal cylindrical chamber, a cylindrical tool-holder yieldingly
mounted in one end of the casing, a tool in said holder, a reciprocating cylinder
mounted in the casing so as to contact the tool-holder at one limit of its motion,
a piston hammer reciprocatingly mounted in the cylinder and arranged to contact
the tool at one limit of its motion, and means for furnishing fluid pressure to the
parts so as to operate the same and alternately drive them so as to contact the tool
holder and the tool alternately, substantially as described.
8. In mechanisms of the class described, the combination of a casing provided
with a longitudinal cylindrical chamber, a cylindrical tool-holder yieldingly
mounted in said chamber at one end of the casing, a tool in said tool-holder, a
reciprocating cylinder mounted in the chamber of the casing and arranged to
contact such tool-holder at one limit of its motion and providing an angular
fluid pressure chamber between it and the casing, a piston hammer reciprocatingly
mounted in said cylinder arranged to contact the tool at one limit of its motion

page_text: providing between it and the cylinder an annular pressure chamber and provided
with a longitudinal opening or passage to alternately admit and exhaust fluid
pressure between the end of the piston and the end of the cylinder to assist the
reciprocating of the parts, and means for furnishing fluid pressure so as to
operate the parts to contact the hammer and holder alternately, substantially as
described.
9. In mechanisms of the class described, the combination of a casing provided
with a cylindrical chamber, a reciprocating cylinder mounted therein having one
end closed and provided with an annular fluid pressure chamber between it and
the casing to drive it in one direction and with pressure inlet openings g³ at one
end and exhaust openings K at or near the opposite end, and a reciprocating
piston mounted in the open end of said cylinder so as to provide a second annular
pressure chamber between it and the cylinder and connected with the inlet open-
ing and providing a second pressure chamber between it and the cylinder and
provided with a longitudinal passage through the piston to furnish communica-
tion with the annular chamber and space between the inner end of the piston and
the closed end of the cylinder with the exhaust openings near the forward end
of the piston, substantially as described.
101 of Tuna 1897
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.