Year: 1887

page_text: Date of Application, 13th Sept., 1887
Complete Left, 24th Dec., 1887
Complete Accepted, 23rd Mar., 1888
I, WILLIAM WILSON HORN, of 151 Strand, Middlesex, Patent Agent, (a com-
munication to me from abroad by John F. Clement of Philadelphia Pennsylvania,
United States of America) do hereby declare the nature of this invention to be as
follows:-
My invention relates to certain new and useful improvements in impact tools and
which invention may be described as follows:-
My invention consists essentially of a ram-cylinder in which a suitable piston or
ram is adapted to reciprocate.
The aforesaid ram is actuated by means of a suitable double-acting pump which is
connected to the aforesaid ram cylinder at both ends thereof, by suitable pipes and is
provided with a pipe by means of which air may enter or leave the aforesaid pipes.
The operation of the aforesaid ram is regulated by means of a valve having two
ports one of which provides a direct communication between the pipe and cylinder
and the other port serves to divert the current. The aforesaid valve is adapted to
work in a suitable valve chest connected with the ram-cylinder. The aforesaid double
acting pump is supported upon a suitable pump carrier mounted upon the post of the
dental engine, and which pump is provided with a pump-operating countershaft and a
driving-belt whereby the said pump operating shaft is operated from the drive-wheel
of the engine. The aforesaid driving belt may be provided with a detachable section,
whereby it may be either used for driving the tool-operating shaft of the engine or the
operating shaft of the pump.
Dth: 101 1
1000

page_text: COMPLETE SPECIFICATION.
An Improved Impact Tool for Dental Purposes.
I, WILLIAM WILSON HORN of the firm of Horn & Son of 151 Strand Middlesex,
Patent Agents (a communication to me from abroad by John F. Clement of
Philadelphia, Pennsylvania, United States of America,) 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 certain improvements in impact-tools-such as tooth-
pluggers, rock-drills, chipping or surfacing machines, &c.—the main objects of my
improvements being to insure the rapid operation of the tool, and to provide a ready
means of regulating the force of the blow."
In the accompanying drawings, Fig. 1 is a longitudinal sectional view of an impact-
tool constructed in accordance with my invention. Fig. 2 is a sectional view of the
pump for operating the same. Figs. 3 and 4 are views of parts of the tool, showing
a controlling-valve adjusted to different positions from that shown in Fig. 1. Fig. 5
is a transverse section of the lower portion of the device. Fig. 6 is a view illustrating
a method of operating a pump for the tool shown in Fig. 1. Fig. 7 is a view of
a valve structure adapted for use in connection with the tool when the latter is
operated by a single-action pump, and Fig. 8 is a view of another single-action tool
with modified form of regulator.
In Fig. 1, A represents a cylinder containing a plunger or ram, B, which can move
freely in said cylinder. The lower end of the cylinder is closed by a tubular plug, a,
in which is guided and free to slide a stem, D, the upper end of which projects into
the cylinder, and has a flange or collar, b, forming a bearing for a spring, d, which is
contained partly in a recess in the inner end of the plug a, and tends to elevate the
stem D to an extent permitted by the head of a stop-screw, f, the stem of the latter
passing through an opening in the flange b, and having a thread adapted to an internal
thread in an opening in the inner end of the plug a, so that by a proper adjustment
of the screw the extent of inward movement or lift of the stem D, due to the action
of the spring d, can be readily regulated.
In the bottom of the spring-receiving recess of the plug a is a washer, i, of rubber
or like material, fitting snugly to the stem D, so as to prevent leakage around the
same.
The tool F is secured to the stem D by means of a transverse key, 9, adapted to
recesses in the tool and stem, the opposite projecting ends of this key being adapted
to vertical slots in the plug a, so that longitudinal movement of the stem, and of
the tool carried thereby, is always permitted, and ready access can be had to the
retaining-key at any time, rapid changing of the tools being thus rendered possible.
With the lower end of the cylinder A communicates a pipe, m, a similar pipe, n,
communicating with the upper end of the cylinder, and these pipes communicate,
through flexible tube p, with pipes n¹ m², respectively at the upper and lower ends of
a pump-cylinder, J, which contains a piston, J¹, the rod k of which is reciprocated in
any suitable manner.

page_text: On the upward stroke of the piston air is forced from the upper portion of the
pump-cylinder into the upper portion of the cylinder A, and drawn from the lower
end of the latter into the lower portion of the pump-cylinder, thus causing the down-
ward movement of the plunger or ram B, which strikes a blow upon the inner end
of the stem D and drives the latter forcibly downward. On the downward stroke of
the pump-piston the action is reversed, air being forced into the lower end of the
cylinder A and drawn from the upper end of the same, so as to cause the elevation of
the ram B, the stem D being lifted by its spring d to the extent permitted by the
stop-screw f.
In
In order to prevent the ram in its upward movement from coming into forcible
contact with the head a¹ at the upper end of the cylinder A, a light spring, 8, is
interposed between said head and the ram, as shown. The movement of the ram B is
thus due both to the direct impulse of the blast of air on one side and the withdrawal
of the air from the opposite side, so that a forcible blow is delivered by the ram.
order, however, that the force of the blow may be regulated during the operation of
the tool, as may be required by the character of the work which is being performed,
I connect the pipes m and n by means of transverse valve-chest, K, in which is a
sliding valve, M, having two ports, t and t, the former passing directly through the
valve, but the port t¹ being right-angled and extending to the end of the valve.
When, therefore, the valve M is adjusted to the position shown in Fig. 1, the flow of
air to or from the upper end of the cylinder A is cut off and a direct communication
is established between the two pipes m and n, so that air flows directly from one to
the other, and no influence is exerted upon the ram B.
When the valve is adjusted to the position shown in Fig. 3, there is a restricted
communication between the pipes m and n, and a restricted communication between
the pipe n and the upper end of the cylinder A, so that the ram is subjected to but
a portion of the full force of the blast, while, when the valve is adjusted to the position
shown in Fig. 4, direct communication between the pipes m and n is cut off and
free communication opened between the pipe n and the upper end of the cylinder A,
so that the ram acts with full force.
The valve M has a projecting stem, which is depressed in order to operate the valve,
a spring, t, serving to move the valve outward.
The valve-stem may be under the influence of an arm, to, at the side of the cylinder,
as shown, for instance, by dotted lines in Fig. 1, so as to provide for the ready operation
of the valve from any point in the length of the cylinder.
The form of valve described may be used with advantage in connection with a tool
operated by a single-acting pump, in which case but a single air-pipe is used, one end
of the valve-chest being open to the atmosphere, as shown in Fig. 7.
Other means within the scope of my invention may be used for regulating the force
of the blow in a single-acting tool. For instance, in Fig. 8 I have shown a con-
struction in which a simple branch tube, c, communicates with the blast-pipe at a
point between the pump and the ram-cylinder, this tube having a series of orifices, c¹,
which may be covered by the fingers of the hand in which the tool is held, the area
of opening for the inlet of air to or its discharge from the branch pipe being regulated
by moving the fingers so as to uncover one or more of the orifices; or the pipe may, if
desired, be open at the end, and may be elastic, so that it can be compressed to a
greater or less extent by the finger, as may be suggested by the desired regulation of
area of the passage provided by the pipe.
The pump shown in this apparatus is a cylinder with a diaphragm, V, instead of a
piston, this form being preferred for use in connection with a single-acting tool.
Prior to my invention pneumatic pluggers have been devised in which the force of
the blow delivered by the ram is regulated by restricting the inlet of air to or its
discharge from the cylinder below the ram, or by restricting the flow through the
blast-pipe; but both of these plans are objectionablo, on account of the back-pressure
or drag upon the pump, which results from such restriction. My invention differs
from these in effecting the regulation, by providing the blast-pipo with means for
supplying said pipe with air, or for the escape of air from said pipe at a point between,

page_text: the pump and the ram cylinder. This independent supply and discharge is in the
nature of a leak in the blast-pipe, and hence weakens the force of the blast or partial
vacuum to the extent of the volume of said leak
Although in the case of the double-action tool there is a partial obstruction of the
communication between the blast-pipe and the cylinder, this is always counteracted by
the provision of an independent means of supply and discharge equal to the obstruction
in the regular communication, so that there is never any back-pressure or drag to
interfere with the perfect freedom and uniformity of movement of the pump, or with
the free reicprocation of the ram in its cylinder.
I can use the ordinary form of dental engine for operating either the double-acting
pump shown in Fig. 1 or the single-acting pump shown in Fig. 8 when my improved
impact tool is to be used as a dental plugger. In this case I bolt the standard
carrying the pump directly to the vertical post or column P of the dental engine, the
driving-shaft u of the pump having a pulley for receiving, as shown by dotted lines
in Fig. 8, the belt & from the drive-wheel S, which is operated by the treadle. Said
shaft is also provided with a crank-disc, y, a rod from which is connected either to
the diaphragm V of the single-acting pump or to the piston-rod k of the pump when
the latter is double-acting.
In order that I may use for the purpose of driving the pump the same belt which
is used for driving the ordinary tool-operating shaft, T, of the dental engine, I provide
said belt with a detachable section, ¹, the removal of which shortens the belt to the
extent necessary to adapt it for driving the pump-operating shaft u, which is some-
what below the shaft T, ordinary hook-and-eye couplings being used to connect the
ends of the belt to the ends of the section ¹ or for connecting the ends of said belt
together when the section ¹ is removed.
I am aware that a pneumatic plugger has been devised in which the pump was
operated by direct connection with the drive wheel S of a dental engine but with such
a device but a few blows per minute can be given to the tool, whereas when the parts
are constructed in accordance with my invention hundreds or thousands of blows per
minute can be given.
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. The combination, in an impact-tool, of the ram cylinder and its ram, a pump,
and a pipe connecting said pump to the ram-cylinder, said pipe having between the
pump and the ram-cylinder a passage through which air can enter or leave the pipe,
all substantially as specified.
2. The combination, in an impact-tool, of the ram cylinder and its ram, a pump,
a pipe connecting the pump and cylinder, and having between the two a passage
through which air can enter or leave the pipe, and means for regulating the effective
inlet or discharge area of said passage, all substantially as specified.
'
3. The combination, in an impact-tool, of the ram-cylinder and ram, a double-
acting pump, and pipes whereby communication is afforded between the opposite
ends of the pump and corresponding ends of the ram-cylinder, all substantially as
specified.
4. The combination of the cylinder and its ram, the movable stem and its lifting-
spring, and a stop-screw independent of said spring and adjustable in a direction
parallel with the line of movement of the stem, so as to limit the lift of said stem by
the spring, all substantially as specified.
5. The combination of the ram-cylinder and ram, a pump, a
pipe connecting the
pump and ram-cylinder, and a valve having two ports, one providing a direct com-
munication between the pipe and cylinder and the other serving to divert the current,
all substantially as specified.
6. The combination of the ram-cylinder and its ram, the pump, the two pipes, ono
communicating with one end of the cylinder and pump and the other with the
opposite ends thereof, a valve-chest connecting the two pipes, and a valve having.

page_text: two ports, one forming a direct communication between one of the pipes and the
cylinder and the other providing a direct communication between the two pipes, all
substantially as specified.
7. The combination of a dental engine, the ram-cylinder and its ram, the pump, and
a connecting-pipe, a pump-carrier mounted on the post of the dental engine, a pump-
operating counter-shaft, and a belt whereby said shaft is operated from the drive-wheel
of the engine, all substantially as specified.
8. The combination of a dental engine, its drive-wheel and tool-operating shaft, a
pump structure mounted on the standard of the engine, and a driving-belt having a
detachable section, whereby it can be used either for driving the tool-operating shaft
of the engine or the operating-shaft of the pump, all substantially as specified.
Dated this 94th day of Decembar 1887