Improvements in Preumatic Impact Tools.
Year: 1898

page_text: Date of Application, 16th Aug., 1893-Accepted, 11th Feb., 1899
COMPLETE SPECIFICATION.
Improvements in Preumatic Impact Tools.
I, SAMUEL OLDHAM, a citizen of the United States, residing at No. 4326, Tacka-
wanna Street, Frankford, in the County of Philadelphia and State of Pennsyl-
vania, Manufacturer, 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 has relation to an impact tool of the valveless class; and in
such connection it relates to the construction and arrangement of such a
tool.
The principal objects of my invention are first, to provide an impact tool of
simple construction, wherein the reciprocating piston or hammer may be caused
to operate with little or no friction on the cylinder of the tool and wherein the
piston or hammer is adapted to reciprocate more quickly and to be maintained
with a uniform fluid pressure on its sides or surfaces in use; and second, to
provide an impact tool with a reciprocating piston or hammer adapted to operate
within its cylinder with friction appreciably reduced, and with the avoidance of
side or surface pressure and with a piston or hammer which is quick to act
and is always maintained at a uniform pressure of the motive fluid on its sides
or surfaces, and further in which the said fluid is permitted to freely pass to.
the upper and lower heads of the piston or hammer without regard to what the
position of the piston or hammer may be within its cylinder.
My invention stated in general terms, consists of an impact tool constructed
and arranged in substantially the manner hereinafter described and claimed.
The nature and scope of my invention will be more fully understood from the
following description taken in connection with the accompanying drawings form-
ing part hereof, in which
Figure 1, is a front elevation of an impact tool embodying main features of my
invention.
Fig. 2, is a similar view with a portion of the outer sleeve or shell broken
away to illustrate the arrangement of the fluid inlet port of the tool.
Fig. 3, is a vertical central section of the tool.
Fig. 4, is a transverse sectional view on the line 4-4, of Fig. 2.
Fig. 5, is a cross-sectional view on the line 5-5, of Fig. 2.
Fig. 6, is a cross-sectional view on the line 6-6, of Fig. 3.
Fig. 7, is a cross sectional view on the line 7-7, of Fig. 4.
Fig. 8, is a side elevational view of the tool partly broken away to show the
means for preventing the hammer or piston from turning in the cylinder and
also to illustrate the location and arrangement of the exhaust ports; and
Fig. 9, is a cross-sectional view on the line 99, of Fig. 8.
Referring to the drawings a, represents the cylinder or casing of the tool.
This cylinder a, is preferably formed of an inner shell a¹, and an, exterior
sleeve, to permit of the formation of the various ports and channels in said
cylinder. At preferably the upper end of the cylinder a, is formed an opening b,

page_text: which extends through the inner shell a¹. This opening b, is in communication
with an opening 13, formed in a screw cap B, closing the upper end of the
cylinder a, to which cap is preferably secured the tube conveying air, gas or
other motive fluid. From the opening b, and between the inner and outer
casings of the cylinder a, is provided a vertical channel ¹. This channel b¹,
terminates in a semicircular groove or channel 62, in cross section, in inlet ports 54
and, in the interior of the cylinder a. The inlet port 64, is preferably dia-
metrically opposite to the inlet port . At a short distance above the port 64, in
the wall of the cylinder «, is provided a port d, and channels, leading to the
upper end of the cylinder and below the port.65, is provided a similar port e,
and channels e¹, leading to the lower end of the said cylinder «. Within this
cylinder a, and snugly fitting its bore is a reciprocating piston or hammer f,
having the cylindrical upper and lower heads f¹ and f, and provided with a
series of concavities and g¹, which when the members of the tool are assembled
are located opposite to and in communication respectively with the inlet ports 54
and 5, as clearly illustrated in Figs. 3 and 5. A concavity g, of the series of
the piston or hammer f, serves in one position to form a means of communication
between the inlet port 64; port d, and channels d, to the interior of the cylinder a,
above the upper head fi, of the piston or hammer f, while in the other position
of the said piston or hammer f, another concavity g¹, of the series forms a
means of communication between the inlet port 65, port e, and channels e¹, to
the interior of the cylinder a, below the lower head f2, of the piston or hammer f.
The upper head f, during the movement of the piston or hammer f will alter-
nately open and close the port d, and the lower head f, at the same time will
alternately close and open the port e. From the interior of the cylinder a,
extends the exhaust ports or channels h, leading from a space at the upper end
of the cylinder to preferably the lower end of the casing a, and from a space at
the lower end of the cylinder the exhaust ports or channels h¹, lead preferably to
the same end of the casing a¹, as illustrated in Fig. 8.
In certain of the figures of the drawings four concavities in the piston or
hammer f, have been shown and described, while in certain of the other figures
of the drawings, but two concavities have been shown and described and herein-
after is fully explained the advantages incident to the use of such in a tool of
my invention.
When four concavities are employed in the piston or hammer there is formed
at the end walls of the same, ribs m, which bear against the wall of the cylinder a,
and appreciably reduce the frictional contact of the piston or hammer f, with its
cylinder a, as compared with the use of two concavities and with the remaining
portions between the said two concavities rounded off and resting against the
wall of the cylinder a. Another advantage of forming the piston or hammer
with four concavities instead of two is that the piston or hammer will freely
turn in the cylinder a, and be always in a position to present concavities opposite
the inlet ports 6 and 65, thereby ensuring the uniform wear through use of the
piston or hammer f.
"
4
To prevent the piston or hammer f, so turning that the concavities of the
same might fail to register with. the said inlet ports 6 and 65, of the cylinder a,
the construction of piston or hammer f, as illustrated in Fig. 8, may be employed
and in which in addition to having only two concavities and g¹, there is provided
in the wall of the cylinder a, a screw-pin n, adapted to enter a vertical slot n',
in one of the heads of the piston or hammer f. This arrangement while it
permits of the reciprocation of the piston or hammer will prevent turning thereof
during operation of the tool. Under this arrangement of the piston or hammer
there is only required for the operation of the tool, the provision of two concavities
opposite each other.
:-- ·
The mode of operation of the tool hereinbefore described, is as follows:-
The motive fluid is caused to enter the cap B, through the opening B¹, and it
then passes into the opening b, in the wall of the cylinder a.
From the open-

page_text: ing b, the said fluid passes through the channel b¹, into the groove b², then
through the ports 64 and 65, respectively and is presented to the concavities of
the piston or hammer f, on opposite sides of the same. When the piston or
hammer f, is in the position as illustrated in Fig. 3, the motive fluid in one
of the concavities g, will pass through the port d, and the channels d', to the
interior of the cylinder a, above the upper head f¹, of the piston or hammer f, to
depress the same. During the downward movement of said piston or hammer
the exhaust in the lower end of the cylinder is forced out through the exhaust
ports h, which are kept open until the piston or hammer reaches its lowermost
position, when the lower head f, will close the ports h¹, and will clear the port,
and permit it to communicate with a concavity g', opposite to that above
mentioned. At the same time the head f¹, will close the port d, and will clear
the exhaust port h. In this latter position, the fluid which has heretofore
remained passive in one of the concavities will now pass through the port e, and
the channel e¹, to the lower end of the cylinder a, below the lower head f of
the piston or hammer f, whereby it will be raised. In the upward movement
of the piston or hammer f, its upper head f¹, will force the air in the upper end
of the cylinder a, through the exhaust ports h.
From the foregoing description it will be readily understood that the piston
or hammer in operation is balanced by reason of its being subjected to equal or
substantially equal pressure of the fluid on opposite sides and that the fluid in
operating the piston or hammer alternately traverses the wall of the cylinder
at points also diametrically opposite. It will also be understood that inasmuch
as the fluid is conveyed directly from opposite concavities to opposite ends of the
cylinder and does not traverse the piston or hammer, the operation of the same
will be more rapid, since it will respond almost instantly to the pressure of the
fluid. Again by concaving the piston or hammer so as to leave ribs at the ends
of the concaved portions of the same, friction between the piston or hammer and
internal bore of the cylinder is reduced correspondingly and there is also permitted
thereby a free turning of the piston or hammer during either movement of the
same within the bore of the tool, thereby ensuring uniform wear of the piston
or hammer in use.
It will be observed, due to the particular construction and arrangement of the
piston or hammer in its bore or cylinder, as illustrated in Figs. 1 to 7, inclusive
that it matters not what the particular position of the same may be the motive
fluid will always be conducted to either the upper or lower heads of the piston
or hammer even if certain of the ribs formed by the walls of the concavities on
said piston or hammer are directly opposite the respective inlet ports 4 and 65,
of the cylinder, because the motive fluid will pass in such instances in two of
the concavities on either side of the piston or hammer without interfering with
the effective working of the piston or hammer f, or conduct of the motive
fluid to the upper and lower heads thereof.
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
1. In a pneumatic impact tool, a cylinder provided with a fluid inlet, a channel
leading from said inlet and a groove forming the terminal of said channel,
ports communicating with said cylinder and leading from said groove, a piston
or hammer having concavities opposite each other and adapted to register with
said ports, inlet ports and channels leading respectively from one of the con-
cavities of said piston or hammer to the upper portion thereof and from the other
of the concavities of said piston or hammer to the lower portion of the same,
substantially as and for the purposes described.
2. In a pneumatic impact tool, a cylinder having a fluid-inlet, a channel leading
from said inlet and provided with a semicircular groove forming the terminal
of said channel, two diametrically opposite ports communicating with the

page_text: interior of the cylinder and leading from the terminal of said groove, a piston or
hammer having two concavities diametrically opposite to each other and adapted
to register with said ports and two inlet ports and channels leading respectively
from one of said concavities to the upper portion of said piston or hammer and
from the other of said concavities to the lower portion of the same, substantially
as and for the purposes described.
3. In a pneumatic impact tool, a cylinder having an inlet port in its wall, a
channel leading from said port, a groove forming the terminal of said channel,
fluid inlets leading from said groove to the interior of said cylinder opposite to
each other, a piston or hammer adapted to reciprocate in said cylinder and having
a series of concavities, whereof each is in communication with one of said fluid
inlets, a port leading from certain of said concavities to a space above the upper
head of said piston or hammer, a port leading from certain other concavities to a
space below the lower head of said piston or hammer, said ports adapted to be
alternately brought into open communication with said fluid inlets through said
concavities during reciprocation of said piston or hammer, and exhaust ports
leading from a space above and a space below said piston heads and adapted to
be alternately opened and closed by movement of said piston or hammer, substan-
tially as and for the purposes described.
SAMUEL OLDHAM,
Per J. G. Lorrain, M.I.E.E., M.I.Mech. E.,
Chartered Patent Agent, Norfolk House, London, W.C.