Improvements in Pneumatic Tools.
Year: 1895

page_text: Date of Application, 8th Jan., 1895--Accepted, 9th Mar., 1895
UUMI LELE STEL
Improvements in Pneumatic Tools.
I, JAMES WOLSTENCROFT, North-east corner Harrison and Willow Streets,
Frankford, Philadelphia, Pennsylvania, Manufacturer, 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:-
This invention relates to devices wherein atmospheric air or other fluid pressure
is used for operating a reciprocating tool employed for stone dressing, 'calking,
riveting, dental use, rock drilling, etc., and it consists in the construction and novel
arrangement of parts as hereinafter set forth.
In the accompanying drawing;
Figure 1, is a longitudinal section of a tool embodying my invention;
Figure 2, is a longitudinal section showing a modification thereof;
Figure 3, is a transverse section on the line 3, 3, of Fig. 2, and
Figure 4, is a transverse section on the line 4, 4, of Fig. 2.
Referring by reference characters to the drawing, A, designates a shell or
casing, having at one end, as here shown, a reduced portion a, within which a tool
holder A', reciprocates. A tubular nut a', surrounds the tool or tool holder and a
spring a², abutting at one end against an interior shoulder of the nut and an annular
shoulder a³, on the tool or tool holder serves to retain and to return the tool or tool
holder to its inner or normal position after being operated upon by the striker. It
will be seen that the tool or tool holder has a very short movement limited by the
walls of an annular chamber a', within which the shoulder a³, is arranged. The
opposite end of the casing A, is provided with a cap A2, having the pressure supply
duct as, and an exhaust port aº.
1n Fig. 1, B indicates the striker of substantially solid metal, and having a
bearing in a reduced portion b, of the casing A. The end of the striker B, adjacent
the tool or tool holder, has an annular pressure bearing surface 6', and from this
surface a duct 2, leads through the striker and has an opening 63, into the
chamber 6, of the casing.
B', designates the distributing valve, having a substantially cup-shaped portion
arranged within and of slightly smaller diameter than the chamber 6, and engaging
around the striker B. This valve has a hollow stem portion B2, communicating
with the interior of the main portion of the valve. This stem portion is movable
in a bushing C, and it is provided with an induction port or ports c, for receiving
air from the chamber 6, and an exhaust port or ports c¹, communicating with the
outlet a. The portion B2, and the closure or bushing C, act as the valve proper
for the admission and exhaust of the operating current. The casing A, is also
provided with an exhaust port or ports c², adjacent the end of the striker, and
controlled by the movement thereof.
In the operation of the device in Figure 1, above described, the reciprocations
of the striker B, and distributing valve B, in opposite directions, are practically
simultaneous, but in a measure successive. Air under constant pressure through
the duct a³, enters the chamber c³, through the ports c, and acting on the upper
surface of the striker drives the same with force against the tool or tool holder, as
shown in the drawing. The pressure also prevailing on the greater interior area of the
valve B', reciprocates it until its exhaust ports extend beyond the bushing or valve
seat C, where the prevailing body of air is exhausted. When the valve B', is in
its exhaust position the opening ³, of the port 62, is uncovered thereby, so that a

page_text: pressure of air rushes through said port 2 and bears against the shoulder , and
the bottom of the striker B, and forces it up until its lower end registers with the
exhaust port c². During this return movement of the striker, and before the
exhaust port c², has been opened, the air pressure on the external shoulder c, of
the valve B', will have moved said valve until the opening 63, is closed thereby,
and the ports c, of said valve are in communication with the chamber pre-
paratory to another stroke. The valve may have a yielding abutment c, and the
striker may have a yielding abutment c°.
Referring now to the example shown in Fig. 2, a striker D, is shown as fitting
the casing A, throughout its interior length; a bushing D', being arranged in
said casing for convenience. In this construction a duct d, for the air pressure to
operate on the part ¹, and bottom of the striker, is formed in the shell or in the
bushing D'.
A
The striker D, in this example is hollow or substantially cup-shaped, and the
enlarged portion d', of a distributing valve D³, operates therein. The striker D,
in this example, serves as a closure for the inlet of the duct d, and thereby directly
controls the induction as well as the eduction of fluid at its striking end.
constant pressure at 6, at the upper end of the striker has to be overcome during
its return movement in the example of Figure 2, but this is wholly obviated in the
example of Figure 1; in other respects the construction and operation are
practically similar in Figures 1 and 2, and in both examples there is no pressure
resistance to the striking movement of the striker.
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. In a pneumatic tool the combination with a cylinder having a tool support at
one end and a valve casing at the other, of a striker fitted to and guided by said
cylinder, and a longitudinally movable distributing valve independent of the
cylinder, fitted to and guided by said striker at one end, and by said casing at the
other end.
2. In a pneumatic tool, the combination with a cylinder having a tool support
at one end and a valve casing at the other, of a striker fitted to and guided for a
portion of its length by said cylinder, a distributing valve independent of the
cylinder having a cylindrical portion at one end surrounding and guided upon a
remaining portion of the length of the striker; said valve guided at its other end
by said casing.
3. In a pneumatic tool, the combination of a casing, a movable striker within the
casing, means for producing the striking movements of the striker, means for
admitting fluid pressure between the striking end of the striker and the tool end of
the casing, and means for exhausting pressure at said striking end, consisting in an
independent exhaust port controlled by the movements of said striker.
4. In a pneumatic tool, the combination of a casing, a movable striker therein, a
distributing valve for controlling the induction and eduction of fluid pressure
above the striker, a duct extending through the striker, also controlled by said
valve for admitting fluid pressure below the striker, and means for exhausting said
fluid below the striker.
Dated this 7th day of January 1801