Improvements in Pneumatic Tools for Stone Planing, Carving, Metal Working, Boiler Calking, and like Operations.
Year: 1892

page_text: Date of Application, 5th Apr., 1892-Accepted, 1st Oct., 1892
COMPLETE SPECIFICATION.
Improvements in Pneumatic Tools for Stone Planing, Carving, Metal
Working, Boiler Calking, and like Operations.
I, DANIEL DRAWBAUGH, of Eberly's Mills, in the County of Cumberland,
State of Pennsylvania, U.S.A. Gentleman, 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 :-
This invention relates to that class of tools ordinarily operated by compressed
air or similar elastic gas and adapted to strike a series of blows with great rapidity,
the force of which is utilized in stone, planing, carving and various kinds of metal
working, such as boiler calking, repousse work, etc., etc., and the objects of the
invention are to improve and simplify the construction whereby the initial cost is
reduced the lateral vibration lessened, the diameter of the tool reduced and the
general efficiency increased.
Broadly stated, the invention may be said to cousist primarily in arranging the
cylinder and valve chest with their longitudinal centers substantially in alignment
and within an integral casing. Further than this the invention consists in certain
novel details of construction and combinations and arrangements of parts to be now
described and pointed out particularly in the appended claims.
Referring to the accompanying drawings:
.
Figure 1 is an elevation of a tool constructed in accordance with the present
invention.
Figure 2 is a longitudinal vertical section taken through the pressure and exhaust
passages.
Figure 3 is a similar view at right angles to Figure 2 showing the passages from.
the valve to each end of the cylinder.
Figure 4 is a sectional perspective of the casing.
Figure 5 is a perspective view of the piston and outside of the bushing for the
valve chest.
Figure 6 is a similar view showing the ports and passages on the opposite side.
Like letters of reference in the several figures indicate the same parts.
The preferred construction of tool in the present instance has the usual casing.
or body section A, to which are screwed the cap piece B and the point section C,
the latter carrying the tool stock C' constructed in the usual or any preferred
manner and as it forms no part of the present invention it will not be further
described.
The casing A is cored out at the lower end to form the cylinder, but instead of
the usual formation the opening is now formed way through the entire casing
longitudinally and utilizes the upper end as a valve chamber thereby bringing the.
longitudinal center of the valve chamber and cylinder into alignment. The portion
of the central longitudinal bore utilized for the valve chamber is preferably of
smaller diameter than the cylinder although not necessarily so, and has fitted within
it a bushing D with a solid lower end and a removable plug d at the upper end,
and suitable ports and passages to be presently described. The valve itself is a
pressure or steam actuated one and the pressure to and exhaust from its opposite
ends is controlled by the piston, the passages for this purpose being formed in the
walls of the casing, but the passages for the pressure and exhaust from opposite
ends of the cylinder are formed almost entirely in the valve bushing or piston
itself, thus as the passages controlling the valve are small, the diameter of the tool
66

page_text: may be greatly reduced and the largest sizes may be made of such proportion as to
be easily grasped by the operator.
Compressed air or pressure is admitted through the cap piece B to which the
supply pipe is attached as usual and from the upper end of the bushing D on the
outside thereof is formed a passage F which will be called 'the live pressure
passage and from which two ports f, f, open into the interior of the bushing in
position to be brought alternately into communication with the ports,, leading
respectively to opposite ends of the cylinder, by means of the valve E.
The ports f,, are formed on each side of the bushing and on the side opposite
the live pressure passage and located in a central or intermediate position is the
exhaust portf³ in direct communication with the exhaust passage Ex of ordinary
or preferred form. The passage leading from the port to the upper end of the
cylinder is a simple exterior channel or groove formed in the bushing and opening
out at the bottom of the same while a similar channel not opening out at the bottom
of the bushing is formed in communication with port and adapted to register
with the mouth or opening g of the channel g! leading down in the wall of 'the
casing to a point below the upper end of the piston H when at the outer extreme
of its movement, at which point it is adapted to register with the elongated mouth or
opening H of the channel H' formed in and opening out at the bottom of the
piston. Instead of passing into the piston this passage may, however, continue
down in the casing as indicated in dotted lines, Figure 3.
The valve controlling the ports in the bushing before referred to is provided
with three pistons or partitions, so to speak, forming between them two annular
chambers adapted to alternately connect each of the ports ff with its pressure
supply port and with the exhaust port and when the latter connection is made;
the port at that end is covered and closed by the end piston or partition, as will
be readily understood by those skilled in the art, such construction being well
known at this day.
For shifting the valve in the present instance, pressure is taken from the live
pressure channel F through a small branch channel formed in the exterior of 'the.
bushing to passage, formed in the wall of the casing and leading down to a point
below the upper end of the piston when at the lower extreme of its movement
where it is provided with ports k¹, k2 which are adapted to register with a single
channel formed in the piston itself, which connect said ports alternately with. 'the
passages, leading respectively to opposite ends of the bushing, or more
properly speaking, communicating with ports k, k', respectively which pass through
the bushing at opposite ends to admit air for moving the valve.
These ports, k, it will be noted, particularly, do not pass through the bushing
at 'the extreme ends but at a point slightly removed therefrom thus forming a positive
air cushion for the valve at each extreme of its stroke and preventing any
possibility of its pounding or striking the end of the casing violently.
"The single passage or channel / formed in the piston for connecting the ports
and k, and and, respectively, is a simple drilled passage having three openings
located in the same transverse plane while the ports, with which the outside
openings register are located in transverse planes separated a distance equal to the
length of the stroke of the piston which construction gives the alternate pressure at
opposite ends of the valve. Corresponding to said passage but above and below
the same are passages which communicate with an exhaust passage formed in the
wall of the casing on the opposite side where an elongated port r is formed which
is constantly open to exhaust. These passages communicate alternately with the
passages,, respectively, to exhaust pressure from the end of the valve opposite
to the end taking pressure. The piston is kept from rotating by a spline working
in the groove, thus keeping the ports and passages in proper alignment.
Referring particularly to Figures 4 and 6 it will be seen that the ports k¹, k³,
and, are round and they are formed by simply drilling through the casing from:
the outside and then plugging the outer ends of the holes, while the corresponding

page_text: ports, b, b' in the piston are somewhat clongated and narrowed toward each end and
hence open communication with and from the valve gradually or in a relatively
gradual manner.
This gradual opening of the ports starts and stops the valve gradually and the
result is accomplished by a structure costing practically no more than if the holes
were simply drilled, no inside cutting of the casing being required.
It will be noted that the whole instrument is simple, inasmuch as the difficult and
complicated passages are entirely in the exterior of the bushing enabling the ports
to be accurately formed and finished without the necessity of extreme accuracy in
making the borings for the passages in the casing.
In the preferred construction the bushing and valve fit within the screw threaded
prolongation of the casing onto which the cap piece screws and the cover or
closure d for the upper end of the bushing is held in place by said cap piece
although it is obvious that a screw thread or other fastening means may be
employed to advantage in some instances.
An annular throttle S as shown may be employed for controlling the exhaust
passage with a stop pin for limiting its movement and a disk friction spring S¹
bearing on its side to prevent accidental movement. The exhaust from the valve
may pass into the main exhaust as has been heretofore proposed without departing
from my invention in the least.
The location of the valves and piston in alignment is of the utmost importance
both because of the advantages pointed out in manufacturing and because it
practically does away with lateral vibration, the jar or shock occasioned by the
valve in the present arrangement being exerted in the same direction as that
occasioned by the piston and being so light is practically unnoticed. By arranging
the ports to cut off at the proper point to cushion the return stroke of the hammer
and the movement of the valve in both directions as will be at once understood by
those skilled in the art, all injurious vibration of the tool is practically annihilated
thus overcoming one of the chief objections to handling this class of instrument.
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 the casing having the cylinder and
valve chamber formed in alignment therein, of the tool stock, the piston, the valve
and ports and passages, substantially as described for admitting pressure to opposite
ends of the piston and valves respectively; substantially as described.
2. In a pneumatic tool, the combination with the casing having the central
longitudinal opening, of the independent valve and piston mounted in said central
opening in alignment with each other with ports and passages under the control of
the valve for admitting and exhausting pressure to opposite ends of the piston and
ports and passages under the control of the piston for shifting the valve; substan-
tially as described.
3. In a pneumatic tool, the combination with the casing having the cylinder and
valve chest formed in aligument therein and separate from each other, of the tool
stock the piston, the valve controlling the ports and passages leading from the valve
chest to the cylinder and the passages leading to opposite ends of the valve
controlled by the piston substantially as described.
4. In a pneumatic tool, the combination with the casing having the central
longitudinal opening therein, and the piston mounted in the lower portion of said
opening of the valve bushing mounted in the upper end of said opening separating
the valve chest from the cylinder and having the ports or channels formed in the
exterior thereof, the valve carried by said bushing, the tool stock and the cap
sections; substantially as described.
5. In a pneumatic tool, the combination with the casing having the central
longitudinal opening therein, of smaller diameter at the upper end, the point and

page_text: cap section and tool stock, of the piston mounted in the larger end of the longi-
tudinal opening in the casing, the valve mounted in the smaller end of said opening
and ports and passages controlled by said valve for admitting and exhausting
pressure to opposite ends of the piston; substantially as described.
6. In a pneumatic tool, the combination with the casing having the central
longitudinal opening of smaller diameter at one end, the tool stock and cap sections,
substantially as described, of the valve bushing mounted in the smaller end of said
longitudinal opening and separating the valve chest and cylinder, the valve carried
by the bushing, the piston mounted in the larger end of said opening and the ports
or passages controlled by the valve for admitting and. exhausting pressure to
opposite ends of the piston; substantially as described.
7. In a pneumatic tool, such as herein described the combination with the casing
containing the cylinder, the piston and tool stock, of the valve bushing carried by
said casing in alignment with the cylinder at one end thereof and having longi-
tudinal channels formed in its exterior communicating with channels leading to
opposite ends of the cylinder, and a valve in said bushing controlling the admission
and exhaust of pressure to opposite ends of the cylinder respectively; substantially
as described.
8. In a pneumatic tool adapted to be held in the operator's hand, the combination
with the casing having the cylinder and valve in alignment with ports and passages
substantially as described, and the piston and valve, of the cap enclosing the end of
the casing, having the entrance port in line with the valve, the point section and
the tool stock movably held in said point section independent of the piston:
substantially as described.
9. In a pneumatic tool, the combination with the casing having the central
longitudinal opening of smaller diameter at one end than at the other, and the piston
mounted in the larger end of said opening, of the valve bushing mounted in the
smaller end of said opening with the longitudinal passages formed in the exterior,
one of said passages opening out at the upper end and constituting a live pressure
passage, another of said passages opening out at the lower end and constituting the
passage to the upper end of the cylinder while an intermediate passage communicates
with a passage in the casing leading to the lower end of the cylinder and a valve
controlling said passages; substantially as described.
10. In a pneumatic tool, the combination with the casing having the cylinder and
valve box, formed therein, with the ports for conveying pressure and exhaust from
opposite ends of the valve opening into the valve box at a point slightly removed
from the ends of the same, and the ports and passages leading from the valve box
to opposite ends of the cylinder, of the valve mounted in the valve box for
controlling said last mentioned ports and passages and the piston controlling the
passages leading to the ends of the valve box; substantially as described.
11. In a pneumatic tool, the combination with the valve and piston with their
enclosing casing having the ports controlled by the piston for operating the valve
opening into the valve box at a point slightly removed from the ends whereby
cushions are formed for the valve at each extreme of its movement; substantially
as described.
12. In a pneumatic tool, the combination with the casing having the independent
valve and piston with the single supply passage having two ports, and the passages
leading to each end of the valve formed in the casing, the single passage in the
piston for alternately connecting the pressure and each passage leading to the valve
and the passage in the piston open to exhaust and alternately communicating with
said last mentioned passages; substantially as described.
13. In a pneumatic tool, the combination with the casing or cylinder with air
passages leading from the air port to each end of the cylinder through the valve
box and from the air port to the cylinder at an intermediate point and from an
intermediate point to opposite ends of the valve box, said intermediate ports being
formed from the outside, of the valve box, the valve working therein and controlling

page_text: the passages leading to the ends of the cylinder and the piston working in the-
cylinder and having air passages for connecting the intermediate ports in the
cylinder leading to the valve, the mouths or ports of said passages in the piston
being elongated and narrowed toward each end, whereby the valve is started and.
arrested gradually; substantially as described.
Dated this 5th day of Anril 1892.
W. P. THOMPSON & BOULT,
Agents for the Applicant.