Improvements in Pneumatic Percussive Tools.
Year: 1898

page_text: Date of Application, 14th June, 1898-Accepted, 7th Jan., 1899
Improvements in Pneumatic Percussive Tools.
I, HERMAN GEORGE KOTTEN, of 150, Nassau Street, New York, United States
of America, Merchant, 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:―
My invention consists of an improved construction of pneumatic tool in which
a solid piston hammer is employed, and consists especially in a novel construction
of exhaust ports, which are located in the chisel bushing and communicate with
the main exhaust, in combination with other ports and passages; so arranged
relatively to each other that the hammer has a comparatively slow movement
away from the chisel or tool employed, but has an exceedingly rapid or accelerated
movement in the direction of said chisel.
It further consists of novel details of construction all as will be hereinafter
fully set forth.
Referring to the accompanying drawing
Figures and 2 represent longitudinal sectional views of a pneumatic tool
embodying my invention, showing the different positions which the piston hammer
thereof assumes at the end and commencement of its stroke respectively, and
Figure 3 represents a section on line x-x Figure 1, showing the relative
positions of the various ports and passages in the cylinder or casing of the tool.
Similar letters of reference indicate corresponding parts in the figures.
1 designates a pneumatic tool, the same consisting of a suitable barrel or
cylinder, which has the inlet port 1 therein, said port communicating with the
passages 2 and 3, which discharge into the main inlet port 4 in proximity to which
is located an annular groove or supply chamber 5, which extends around the
interior periphery of the cylinder 1, whereby no side pressure upon the piston
hammer A can exist and the same can reciprocate freely in either direction.
6 designates an inlet port communicating with the interior of the cylinder, a
short distance at one side of or to the right of the chamber 5 said port 6 leading
into the passage 7 and port 8, which opens into the cylinder near the chisel end
of the tool, in the present instance, at a point adjacent to the termination of the
chisel bushing 18.
11 designates a plurality of exhaust ports which pass through the chisel
bushing 18 and communicate by the annular passage 12 with the main exhaust
passage 10, which discharges into the atmosphere through the port 13, said exhaust
ports 11 being controlled by the nose or projecting striking face A of the piston
hammer A, which latter consists of the enlarged portions B, D, F, which are
connected by the grooves or reduced portions or necks C and E, said nose A
entering the bore 18* of the chisel bushing 18 when said hammer is near the
end of its stroke, it being noted that said nose moves entirely out of said bore 18*
when near the other end of its stroke.
14 designates an inlet port located a slight distance to one side of or to the left
of the main inlet port 4 and communicating with the passage 15 which admits the

page_text: motive fluid to the interior of the cylinder through the port 16, located at the
right hand portion thereof.
17 designates a chisel or tool which is held in the chisel bushing 18, said
bushing being held in position by means of a latch pin 19 or any other suitable
fastening device.
The operation is as follows:
The fluid supply pipe (not shown) is connected with the inlet 1 of the cylinder
and the motive fluid entering the cylinder passes to the main inlet port 4 and the
annular supply chamber 5.
In Figure 1 the piston hammer A is shown at or near its extreme downward
or left hand position at the point where it contacts with the chisel or tool 17, the
chamber 5 being now in communication with the port 6 through the medium
of the neck or groove E of said hammer. The motive fluid passes through the
port 6 and channel 7 and enters the cylinder at the port 8 in proximity to the
chisel bushing and since the latter is secured within the cylinder or casing,
the pressure of the motive fluid drives the piston hammer back or away from the
chisel.
When the piston hammer is in the position seen in Figure 1, the exhaust
port 9, which is substantially one-fourth the area of port 11, is open and allows
the pressure within the cylinder upon the back or right hand end of said hammer,
to escape through the passage 10 and port 13 into the atmosphere.
The motive fluid after passing through the port 8 in the front of the cylinder,
drives the hammer upwardly or towards the right until said hammer closes the
supply chamber 5, at which time no motive fluid can enter the port 6, passage 7
and port 8 in the front end of the cylinder, but the expansion of the compressed
air will drive the hammer still further back until the reduced end thereof leaves
the bore 18 of the chisel bushing, in which latter it has an air tight fit and opens
the exhaust port 11 in said bushing, by means of which communication is had
with the port 12, passage 10 and the main exhaust port 13 leading to the
atmosphere.
At about this period the supply chamber 5 is in communication with the port 14
as indicated in Figure 2, by reason of the neck or groove C and the motive fluid
passes through the port 14 and passage 15 and enters the back or extreme right
hand end of the cylinder through the port 16, and the hammer is driven forcibly
and rapidly into contact with the chisel or tool 17.
When the hammer is in the position indicated in Figure 2, the exhaust port 11
is open and permits all the air to escape from the front end of the cylinder out
through the port 12, exhaust passage 10 and main exhaust port 13, into the
atmosphere.
When the hammer in its downward stroke closes the supply chamber 5, no
more air can enter the back or right hand end of the cylinder but the expansion
of the compressed air will drive the hammer downwardly until the latter contacts
with the chisel or tool and at about this period opens the exhaust port 9, again,
the parts then appearing as seen in Figure 1.
It will be evident that since the hammer in the above described tool works only
for one-quarter of its stroke at a direct pressure and the remaining three-quarters
of said stroke, by expansion, the tool uses the motive fluid very economically and
as the inlet port 8 on the front end of the cylinder is but one-quarter the size of
the inlet port 16 on the back end of the cylinder and since the exhaust port 9 on
the back or right hand end of the cylinder is but one-quarter the size of the
exhaust ports 11 on the front or chisel end of the cylinder, the hammer has a
comparatively slow backward movement and a very rapid forward movement in
the direction of the chisel or tool, thereby striking a very hard and rapid blow
thereon.
It will be understood that the terms right and left or front and back end of the
tool are merely relative terms, the chisel end of the tool being termed the front
and the opposite end the back end.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1st. A pneumatic tool having its inlet port in the front end of the cylinder,
substantially one-quarter the size of the inlet port on the back end of the cylinder,
and the exhaust port on the back end of said cylinder substantially one-quarter
the size of the exhaust port on the front or chisel end of the cylinder, and all of
said ports being controlled by the piston hammer, whereby a comparatively slow
backward movement and a very fast forward movement of the hammer is obtained.
2nd. In a pneumatic-tool, a cylinder having a piston therein, the striking face
or nose of said hammer being of reduced diameter, a chisel bushing in which said
nose has an air tight fit when the hammer is in its extreme forward or downward
position, an exhaust port controlled by said nose and leading to the atmosphere,
said nose being adapted to be moved out of said bushing, and other inlet and
exhaust ports whereby movement is imparted to said hammer.
3rd. In a pneumatic tool, a cylinder, a piston hammer contained therein, said
hammer consisting of the grooved portions or necks C, E, the solid portions B,
D, F of greater diameter and the nose A of reduced diameter, in combination with
inlet and exhaust ports for admitting and exhausting the motive fluid to and from
said cylinder, certain of said exhaust ports being controlled by the nose of said
hammer.
4th. In a pneumatic tool, a cylinder and a main inlet port having an enlarged
supply chamber communicating therewith, said chamber being located within
the interior periphery of the cylinder, whereby no side pressure on the hammer
exists, and other inlet and exhaust ports located within said cylinder, in combi-
nation with a hammer having a nose of reduced diameter, said nose being adapted
to control certain of said exhaust ports.
5th. In a pneumatic tool, a cylinder having a chisel bushing secured therein, a
piston hammer having a nose adapted to have an air tight fit in said bushing,
when said hammer is in its extreme forward position, an exhaust port passing
through said bushing, and communicating with a main exhaust passage in said
cylinder, a main inlet and other inlet and exhaust ports for enabling motion to
be imparted to said hammer.
6th. In a pneumatic tool, a cylinder having a main inlet port 4, an annular
supply chamber 5, communicating therewith, inlet ports 14, 16, and a communi-
cating passage 15 located in said cylinder, other inlet ports 6, 8, and a
communicating passage 7, a chisel bushing having a portion of reduced diameter
into which the nose of the hammer is adapted to enter, exhaust ports 11 in said
chisel bushing communicating with a port 12 which leads to the main exhaust
passage 10 and an exhaust passage 9 communicating with said main exhaust, said
hammer consisting of the portions B, D, F, connected by the necks C, E of
reduced diameter, the nose of said hammer being adapted to enter said chisel
bushing.
7th. In a pneumatic tool, a cylinder, a chisel bushing therein, exhaust ports
extending through said bushing to an annular passage and thence to the atmos-
phere, a piston hammer adapted to reciprocate in said cylinder and provided with
a nose of reduced diameter, said nose controlling said ports and means for
actuating said hammer.
8th. A pneumatic tool, consisting of a cylinder having an inlet port in the front
end thereof substantially one-quarter the size of the inlet port on the back end
thereof, and an exhaust port at the back end thereof substantially one-quarter
the size of the exhaust port on the front or chisel end thereof, and a hammer in.
said cylinder provided with a reduced nose, the latter being adapted to control
said exhaust port at the chisel end of said cylinder.
9th. In a pneumatic tool, a cylinder, a piston hammer contained therein and
provided with a nose of reduced diameter, exhaust ports in said cylinder controlled
by said nose and means for actuating said hammer.

page_text: 10th. In a pneumatic tool, a cylinder having a main inlet port for the motive
Huid, an enlarged supply chamber communicating therewith, and located within
the interior periphery of said cylinder, a piston hammer movable in said cylinder
and provided with a reduced nose, a chisel bushing in said cylinder, which said
nose is adapted to enter and an exhaust port in said bushing controlled by said
nose.
11th. In a pneumatic tool, the combination of a cylinder having a chisel
bushing with an exhaust port therein, a piston hammer having a nose of reduced
diameter controlling said port, and means for reciprocating said hammer.
12th. In a pneumatic tool, the combination of a cylinder, a chisel bushing,
inserted therein, a plurality of exhaust ports extending through said bushing and
communicating with an annular massage, the larger leading to the atmosphere, a
solid hammer in said cylinder provided with a nose of reduced diameter adapted
to control said ports, and means for imparting to said hammer a comparatively
slow backward movement and a very fast forward movement.
13th. In a pneumatic tool, a cylinder, a piston hammer adapted to reciprocate
therein, said hammer being provided with a projecting striking face, an exhaust
port in said cylinder controlled by said striking face and other ports controlled
by said hammer for actuating the latter.
Dated this 9th day of June 1898
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.