Improvements in Pneumatic Percussive Hand Tools.
Year: 1892

page_text: Date of Application, 29th Nov., 1892-Accepted, 28th Jan., 1893
COMPLETE SPECIFICATION.
Improvements in Pneumatic Percussive Hand Tools.
We, JOHN GUGLIELMINOTTI CARLINET, of Seven Stars Hotel, Draughtsman,
JAMES WOLSTENCROFT, of 1701, Harrison Street, Manufacturer, WILLIAM
O'NEILL, of Frankford Avenue, near Wakeling Street, Manufacturer, and
WILLIAM HENRY SOLEY, of 1926, Harrison Street, Machinist, all of Philadelphia,
Pennsylvania, United States of America, do hereby declare the nature of the
said invention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
The object of the invention is to so construct a pneumatic percussive hand tool
as to avoid the jar caused by the striking of the tool upon the article being cut.
This object is attained in the following manner, reference being had to the accom-
panying drawing, in which :-
Fig. 4, is a section on the line 3-4, Fig. 1.
Fig. 5, is a section on the line 5-6, Fig. 1.
Fig. 6, is a longitudinal sectional view of the tool having a compound plunger.
Fig. 7, is a longitudinal sectional view of a tool made in accordance with my
invention in which both plungers are striking plungers.
Fig. 8, is a section on the line 7-8, Fig. 7, and-
Fig. 9, is a view of a modification of the tool shown in Fig. 7.
Pneumatic tools as ordinarily constructed are very hard upon the operator, the
trembling of the tool, owing to the number of strokes given, prevents the operator
from working with the tool continuously, the strain upon the nerves being very
great, as the operator practically takes all the back thrust of the tool when its
plunger is driven forward, and the main object of the invention is to overcome this
difficulty, although it is wished to cover other points relating to the general con-
struction of the mechanism by which quick action is attained, at the same time
making the tool of simple elements that can be readily manufactured and put
together.
A, is the casing, hollow throughout its entire length, forming the cylinder a. At
one side of the casing is formed a passage b, terminating in a coupling head b', at
the rear end of the tool, to which the tube may be attached.
This passage b, is connected with the cylinder chamber a, through the passages b³, b³,
as clearly shown in Fig. 1.
At the rear of the casing A, is an extension casing A¹, screwed into the casing A.
At the forward end of the casing is another extension A², also screwed into the
casing A. This casing A2, carries the impact tool.
D, and E, are two plungers, D, being the striking plunger, and E, the re-action
plunger. The plunger D, has a head d, in which are suitable packing rings.
This head fits snugly within the cylinder a, and can be reciprocated from the
centre, to the packing or cushions f, which are mounted between a shoulder on
the casing A, and the face of the extension A².
The plunger D, fits snugly in the packing f, and extends to the head F, carrying
the tool F. This tool is secured to the head by a set screw f', or by other
means.
Between the head F, and a shoulder on the extension A2, is a cushion f', which is
compressed slightly when the head F, is struck by the plunger D, the head
returning to its normal position after being struck, owing to the character of the
cushion.

page_text: In the extension A², is an opening a¹, to allow the free escape of any air that
may pass beyond the head d, of the plunger, and into the space between the head F,
and the plunger.
The air under pressure passes through the tube b, into the passage b², to the
centre portion of the cylinder a, causing the plunger to strike the blow. The
plunger is returned to its central position owing to the pressure of air in the
space g, back of the head d, the central space being open to the atmosphere.
In order to so operate the valves as to allow the plunger to return to its normal
position, the mechanism is constructed in the following manner.
As before remarked, E, is the reaction plunger having a head e, and provided
with suitable packing rings. This head fits snugly in the cylinder a, and projects
into the extension A', as clearly shown in Fig. 1, this plunger E, is hollow, and
adapted to the plunger is a piston G, which is secured to a piston rod G', carried
by a head G2, which has a slight reciprocating motion within the plug H,
being limited in its motion by a pin h, which passes through a slot in the
head G².
The plug H, is adjustable, and by turning it the valve piston G, can be so
adjusted as to regulate the position of the plungers E and D, and consequently
increase or diminish the blow given by the plunger D.
A spring is mounted between the head G2, and the plug, so that when the
piston G, is acted upon by the air in the centre portion of the cylinder a, it
will compress the spring a sufficient distance to allow the valve to operate
properly.
A set screw ³, regulates the movement of the piston G.
The inlet passage i, communicates with an annular space, which in turn com-
municates with the air inlet passage 62. The passage i, as shown in Fig. 1, when
the pistons are apart, is closed, preventing air gaining access to the centre portion
of the cylinder u, but allowing both plungers to return to their central positions,
air pressure being at the back of the heads d, and e.
The air in the centre portion of the cylinder, when the stroke has been made, is
exhausted through the exhaust passage k, to a chamber K, back of the piston E,
from which it escapes to the atmosphere through ports k¹.
It will be noticed that compressed air is at all times at the back of the
plungers D, and E; the area of the back of each plunger is less than the face,
and consequently the moment the admission port i, is closed and the space between
the plungers is open to exhaust, the plungers will be returned to their central
positions. When the plungers reach this position, however, the air inlet port i, in
the plunger E, passes the end of the piston G, thus allowing air under pressure to
enter the centre portion of the cylinder, and in the meantime the exhaust port k,
is closed by the head G, thus preventing the escape of air through the passages
without first acting on the two plungers.
Between the casing A, and the extension A', is a cushion packing l, similar to
the cushion packing, at the opposite end of the tool.
Thus, it will be seen that while the stroke is sufficient to give the ordinary blow
upon the tool, the plunger E, receives the back thrust, so that the operator holding
the casing A, will not be subjected to the trembling of the tool as heretofore.
In Fig. 6, we have shown a tool similar in construction to that shown in Fig. 1,
with the exception that the plunger D, is made in two parts for the purpose of
returning the plunger proper D', to its normal central line x, at each stroke.
There is sufficient lost motion between the sleeve section D2, and the centre
section D¹, to allow for any rebound of the central section of the plunger D', as the
air will act upon the tubular section D³, and move it, at the same time the air will
move the plunger E, and the central section D', of the plunger will not be moved
to its central line until it is acted upon by the tubular section D', thus always
insuring the return of the plunger to its centre line, and not have it pass beyond its
line, or not to the line.
In Fig. 7, a modification is shown of the tool in which both plungers strike a

page_text: blow on the tool carrying head F, the plunger E, having an extension E', which
passes through the plunger D, and this extension is so situated in respect to the
head that when the plunger E, returns to its centre position it will strike a blow
on the head F; so that in this instance both the plungers D, and E, strike a blow,
the plunger D, striking a blow when the plungers are separated and the plunger E,
striking a blow when they are drawn together as readily understood by referring to
Figs. 7 and 8.
The valve mechanism in this arrangement is somewhat different from that shown
in Fig. 1, the fluid passage b, communicates with a circular passage, which has
one or more partitions 63, allowing the fluid to pass under the plunger D, while the
passage b², to the space back of the plunger E, is formed in a ring, and mounted
loosely within the plunger E, is a cylindrical valve G³, which can slide within the
space shown so as to cut off or expose the opening 2, for the admission and exhaust
of fluid.
When the plungers are separated as shown in Fig. 7, the fluid escapes through
the passage, chamber H, passage, to the exhaust chamber K', but when the
plungers are brought together the inlet opening 3, communicates with the steam
passage and steam enters the passage K, and into the space between the plungers.
The valve G, however, being loose within the plunger E, will cut off the steam,
owing to its momentum as it will close the opening 2.
In Fig. 9. we have shown one plunger mounted within the other and the steam
inlet ports arranged on each side of the head of the central plunger so that when
steam is taken at one end the plunger will strike and the other retract, while when
the steam is taken at the opposite end the movement is reversed. A cushion is used
to limit the movement of the plungers.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. The combination in a pneumatic tool, of the casing, the tool carrier or tool,
plungers in the casing, both of said plungers being mounted in the casing and
independent of each other, with ports and valves whereby the plungers are moved
from a central line outwards in opposite directions and return to the central line
simultaneously, substantially as specified.
2. The combination in a pneumatic tool, of the casing, a tool carrier or tool, the
striking plunger D, and a counteracting plunger E, both mounted in the casing
and independent of each other, with ports and valves whereby the plungers are
moved from the central line outwards in opposite directions and returned to the
central line simultaneously, substantially as specified.
3. The combination of the casing A, the passage at the side of said casing
having inlet ports 62, 63, plungers D, and E, a tool head acted upon by the
plunger D, a piston G, within the plunger E, ports in said plunger, whereby as
compressed air or other fluid is admitted through the inlet passage, the plungers
will be moved apart and brought together, substantially as described.
4. The combination of the hollow casing A, having extensions A¹, and A²,
a passage b, at the side of the casing, with inlet ports 12, 63, communicating with
the interior of the casing, a tool head carried by the extension A³, and a piston G,
carried by the extension A', the striking plunger D, and counter acting plunger E,
passages in said counter acting plunger so situated in respect to the piston G, as to
automatically cut off the supply and exhaust, substantially as described.
5. The combination of the casing A, the inlet ports therefor, the plungers D,
and E, within the said casing, a tool head upon which the plunger D, acts, a
piston G, within the plunger E, inlet and exhaust ports in the plunger E, with
mechanism for regulating the position of the piston G, in relation to the ports,
substantially as described.
6. The combination of the casing A, inlet ports therefor, the plunger E, inlet
and exhaust ports therein, a piston acting in conjunction with the said ports, with a

page_text: two-part striking plunger D, one adapted to slide within the other, substantially as
described.
7. The combination of the casing A, the inlet tube b, passages 62, and 63, forming
communications between the tube and the interior of the casing, a tool head carried
by the casing, a tool striking plunger D, having a head d, and a counter acting
plunger E, having a head e, inlet ports i, and exhaust ports k, in the plunger E,
a piston G, mounted within the plunger, the forward movement of the plunger
being caused by the air or other fluid entering the central portion of the chamber
between the two plungers through the passage 62, and passage i, and the return
movement of the plunger being caused by air acting upon the rear of the heads of
the plungers, substantially as described.
8. The combination of the casing A, inlet ports therefor, the tool head, the tool
plunger D, and the counteracting plunger E, having inlet and exhaust ports therein,
a piston G, mounted within said plunger E, a head G2, connected to the plunger, a
spring back of said head, substantially as described.
9. The combination in the casing A, of the inlet ports therefor, the plungers D,
and E, inlet and exhaust ports in the plunger E, piston G, within the said plunger,
a head G², carrying said piston, a spring, with mechanism for adjusting the piston G,
in relation to the ports in the plunger E, substantially as described.
10. The combination in a pneumatic tool, of the casing, the plungers D, and E,
therein, a tool head at one end of said casing, and an adjustable valve carrying plug
at the opposite end of the casing whereby the force of the blow is regulated, sub-
stantially as described.
11. The combination in a pneumatic tool, of the casing, with two plungers therein,
a tool carrier, said plungers operating alternately upon said tool carrier, sub-
stantially as described.
12. The combination of the casing, the cylindrical plunger D, a plunger E,
having an extension E¹, passing through the plunger D, with a tool carrier against
which both plungers strike, with valve mechanism therefor, substantially as
described.
Dated this 18th day of November 1892.
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C., Agents for the Applicants.