mprovements in Fluid Pressure Percussive Apparatus, the Invention, being Particularly Adapted to Hand Tools.
Year: 1899

page_text: Date of Application, 6th June, 1899-Accepted, 26th Aug.,
1899
COMPLETE SPECIFICATION.
mprovements in Fluid Pressure Percussive Apparatus, the Invention,
being Particularly Adapted to Hand Tools.
We, EDWARD CHARLES MEISSNER, a citizen of the United States, residing at
210, Vine Street, City of St. Louis, State of Missouri, United States of America,
Manufacturer, and PETER HENRY MURPHY, a citizen of the United States, resid-
ng at 524, Brighton Place, City of East St. Louis, State of Illinois, United
States of America, 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:-
-
The invention is illustrated in the accompanying drawings, in which:
Figure 1 is a longitudinal sectional view through our improved percussive
tool showing the piston in its rearmost position.
Figure 2 is a similar view, the handle being omitted, showing the piston in
its forward position.
Figure 3 is a similar view showing the piston in its extreme forward position.
Figure 4 is a view showing the rear face of the valve block.
Figure 5 is a longitudinal sectional view through said valve block.
Figure 6 is a view showing the front face of the valve block.
Figure 7 is a cross sectional view on line 7-7, Figure 5.
Figure 8 is a cross sectional view on line 8-8, Figure 5.
Figure 9 is a longitudinal sectional view through line 9-9, Figure 8.
Figure 10 is an edge view of a sleeve which is introduced into the rear end of
the valve block.
Figure 11 is a cross sectional view through said sleeve.
Figure 12 is a rear end elevational view of the barrel or cylinder.
Figure 13 is a longitudinal sectional view of said barrel or cylinder.
Figure 14 is a cross sectional view through said cylinder on line 14-14, of
Figure 13.
Figure 15 is a cross sectional view through said cylinder on line 15-15,
Figure 13.
Figure 16 is an elevational view showing the handle and a portion of the
cylinder, the flange of the handle being broken away to more clearly show the
manner of locking the coupling sleeve in position.
Figure 17 is a rear edge elevational view of the coupling sleeve, clamping the
cylinder and handle together, and
Figure 18 is a longitudinal sectional view through said coupling sleeve.
This invention relates to a new and useful improvement in fluid pressure
percussive apparatus of that class commonly known as pneumatic hammers, in
which a chisel or tool is loosely introduced into the nose of the cylinder for
receiving impacting blows from the piston. The apparatus or tool is designed
to be held in the hand of an operator, and guided in its work. Fluid pressure,
usually in the form of compressed air, is supplied to the apparatus through the
medium of flexible hose or supply pipe, which is connected to the outer end of
the handle. A throttle valve under control of the operator, controls and regulates
the admission of pressure fluid to the engine.

page_text: The object of this present invention is to construct an apparatus of the
character described, which is simple, cheap and effective in operation, and one
which is free from vibrations usually present in engines of this class, which vibra-
tions render the handling of the tool by the operator extremely tiresome and
difficult.
With this object in view, the invention consists in the novel construction of
the throttle valve, the means for adjusting the tension of its spring, and the
means for regulating or controlling said valve; another feature resides in the
construction of the cylinder, valve block and handle base, whereby said parts
are coupled by the sleeve or collar, and in the provision of means for locking said
sleeve or collar in its home or adjusted position; another feature resides in the
novel construction and method of operation of the piston controlling valve;
another feature resides in the construction of the piston and the port arrange-
ments for admitting pressure to actuate the same, whereby, in the absence of
a tool shank upon which the piston is to deliver a blow, said piston will be moved
forwardly to an abnormal position and cease reciprocating, the pressure being
delivered only at one point, to wit: at the rear of the piston, and said port
arrangements being such that, upon the introduction of the tool, the piston will
be moved rearwardly into an operating position, and immediately commence
reciprocating other features reside in the construction, arrangement and com-
bination of the several parts, all as will hereinafter be described, and afterwards
pointed out in the claims.
In the drawings a indicates a handle provided with a suitable inlet duct or
port, through which the pressure is supplied to the engine. This port terminates
at the outer end of the handle, and a threaded opening b, is provided for the
attachment of the hose or suitable nipple. e indicates a thimble threaded into
the base of the handle and across a live pressure chamber d, said thimble receiv-
ing a sliding throttle valve e, which is held in a closed position by a spring f
A rod g, slidingly mounted in the handle, bears against the valve e, at one end,
and a lever h, pivoted at i bears against the other end of rod g.
The spring f, which tends to hold the throttle valve home, bears at its other
end against a nut j, which is interiorly threaded in the thimble c. Nut j is
provided with an outwardly extending stem k, angular in cross section, which is
received in a correspondingly shaped opening in a cap piece 7, which is held in
its outer position by a spring m, interposed there-between and the nut j.
A pinn, introduced into the outer end of thimble c, after the parts are
assembled, bears against the outer face of the flange on the inner end of the cap
piece, and fits in suitable notches o, provided in the outer face of said flange,
whereby, when said cap piece is pressed inwardly, it slides on stem k, and being
disengaged from the pin n, is capable of being turned to adjust the nut j, in-
wardly or outwardly, which adjustment regulates the amount of travel, and con-
sequently the available area of the throttle valve. When pressure is released
from the cap piece, the spring m forces the same outwardly, and causes an
engagement between one of the notches thereof, and the pin n, which prevents
accidental rotation of the parts.
A by-pass p, is provided within the thimble c, to conduct pressure behind the
throttle valve for the purpose of balancing said valve when in an open position,
so that the same may be easily operated by its spring, and also, for assisting
in holding said valve in a closed position.
The supply duct d, is located to one side of the slot q, in which the lever h
is mounted, and opens into a concentric groover, in the handle base. The
handle base is provided with an interiorly threaded flanges, which engages a
collar or coupling sleeve t, whose forward end is provided with an inturned
Hangeu, fitting over a ring or flange v, formed at the rear end of the cylinder,
The valve block, or that part of the engine which receives the piston controlling
valve, is clamped between the handle base and the end of the cylinder, by means
of this coupling sleeve, and in order to lock the coupling sleeve in its home posi-

page_text: tion and prevent accidental unscrewing thereof, which would seriously affect
the operation of the engine, we notch, or form a series of serrations w, on the
rear edge of this coupling sleeve, as shown more clearly in Figures 16, 17 and 18,
and mount in the flanges of the handle, a spring pressed pawl or dog a, which
is permitted to ride over said serrations, when the collar is being screwed home,
and which prevents the accidental unscrewing of said collar. This dog a is
mounted on a stem, around which is wound a torsional spring y, one end of said
torsional spring entering the flange, and the other end the stem, or a cap piece,
arranged on the outer end of the stem, and by which the same can be turned to
raise the dog out of engagement with the serrations on the end of the coupling
sleeve whenever it is desired to unscrew the said sleeve. The operation of this
dog is shown more clearly in Figures 1 and 16.
We will now describe the port arrangements, and the manner in which pres-
sure is admitted to the piston and its controlling valve. The cylinder or barrel,
which we have marked 20, as an entirety, is bored to two different diameters,
the larger of which receives the head 21, of the piston, and the smaller, the body
portion 22 of said piston, said body portion having a reduced annulus 23. When
the chisel shank is in position, the piston moves forward and delivers an impact-
ing blow, being arrested at such forward movement at practically the point
indicated in Figure 2. Ports 24, 25 and 26 open into the forward end of the
larger bore of the cylinder, near the shoulder or the beginning of the smaller
bore, these ports registering with corresponding ports 27, 28 and 29, formed in
the valve block, and which open at their rear ends into the live pressure chamber
or concentric groove r. Pressure is thus conducted under, or in advance of, the
larger head of the piston, and tends at all times to force said piston rearwardly.
In other words, there is a constant pressure in advance of the piston, and an
intermittent pressure behind the larger head of the piston. This intermittent
pressure is controlled by a valve 30, preferably centrally arranged relative to
the valve block, said valve being of two different diameters, the larger which we
have marked 31, being on the forward end of the valve, while the smaller 32,
forms the rear end of the valve. These two portions of the valve are divided by
an enlarged head or flange 33, which operates in what may be called the largest
bere 34, of the valve block. This valve block, as shown more clearly in Figures 5
and 9, is bored to three different diameters, the largest of which receives a
sleeve 35 (in the rear end of the valve block), and the bore of this sleeve forms
a chamber in which the smallest diameter 32 of the valve operates. The central
head of the valve operates in the bore 34 of the valve block as above described,
while the larger body portion of the valve operates in the smallest bore 36, of
the valve block, Sleeve 35 has a seat formed in its rear end, in which is received
à solid plate 37, while the valve block and sleeve are formed with radial openings
registering with each other, which we have marked 38, said openings leading to
an exhaust space or chamber 39, formed between the flange of the handle base
and valve block, said chamber communicating with the atmosphere through
openings 40.
Valve 30 is formed with an axial opening 41, extending entirely through the
same, which opening, when the valve is moved forwardly, serves to exhaust
pressure from the rear end of the cylinder, said pressure escaping through the
openings, 38, which are enclosed when the valve is in such forward position
When the valve is thus forward, the body portion 31, projects a little distance
into the cylinder, and is designed to co-operate with a stem 42, on the
piston to be hereinafter described. Each of the ports 27, 28 and 29 open into
the bore 36 of the valve block, through ports 43, which ports 43 are opened and
closed by the larger body portion 31, of the valve in its reciprocation. Leading
from the rear end of the bore 34, of the valve block, is a duct or passage 44,
which opens into the smaller bore of the cylinder near its rear end, said passage
being opened or closed by the forward end of the piston by its reduced annulus 23,

page_text: which annulus in one position of the piston admits pressure into the bore 34,
and in another position of the piston establishes communication between the
duct 44 and the exhaust opening 45 in the cylinder, located slightly in advance
of the port 44. In order to accommodate the displacement of air in the bore 34
in front of the head of the valve, we provide a port 46, and which opens into the
exhaust chamber 39 through a groove 47, as shown more clearly in Figures 8
and 9. This port 46 serves no purpose except to relieve the valve of pressure in
front of its head when the same moves forwardly, and to admit air at atmo-
spheric pressure when the valve moves rearwardly.
The operation of the engine as above described, is as follows; Assuming the
parts to be in position as shown in Figure 1 and pressure admitted to chamber d,
when lever is moved forwardly, it will unseat the throttle valve to admit
pressure to the annular chamber r, from which chamber pressure is conducted
through to ports 27, 28 and 29, in registration with the ports 24, 25 and 26,
and admitted into the larger bore of the cylinder near the forward end thereof.
Under such conditions, the tendency of the piston is to move rearwardly, and in
so doing the stem 42 contacts with the forward end of valve 30, and forces said
valve rearwardly so as to close the exhaust ports 38, and open the inlet ports 43,
to admit pressure behind the piston. The piston now moves forward as the
area of the rear end of the piston exceeds the area of the shoulder, being the
difference between the larger and smaller bores of the cylinder, said forward
movement continuing until the reduced annulus 23 opens the port 44 to pressure,
which port admits said pressure behind the head of the valve, causing said valve
to move forward, as shown in Figure 2. The forward end of the piston now
delivers an impacting blow on the shank of the chisel introduced into the end
of the cylinder, after which the pressure behind the piston exhausting through
the axial bore 41 of the valve, the exhaust passages 38, the exhaust chamber 39,
and into the atmosphere through the openings 40, will permit the pressure in
front of the larger head of the piston to move said piston rearwardly until its
stem 42 contacts with the forward end of valve 30, and moves said valve rear-
wardly to close the exhaust passages 38, and open the inlet passages 43, as above
described.
It is desirable in this class of apparatus to provide means whereby the piston
will cease operating in the absence of the tool shank, without necessitating the
operator closing the throttle valve every time he changes the position of the tool
with respect to the work being done, and to accomplish this we permit the
piston to move forwardly to an abnormal position, in the absence of the tool
shank, so as to open the ports 50, 51 and 52, being at the extreme forward ends
of ducts 24, 25 and 26, and, which in normal operation were in front of the
larger head 21, of the piston, and also, open ports 53, 54 and 55, leading from
ports 24, 25 and 26 respectively, just to the rear of ports 50, 51 and 52. No
pressure now being in front of the piston, under these conditions, the pressure
behind the piston will hold it in such forward position until the tool shank is
again inserted to move the piston rearwardly to the position shown in Figure 2,
or to such position that the ports 50, 51 and 52 will be opened in front of the
larger head 21, of the piston. It is obvious that when the piston is in its extreme
position, as shown in Figure 3, being its abnormal forward position, the valve 30
is in its rearward position, and is admitting pressure behind the larger head 21
of the piston, through the ports 43, which pressure can, in some instances, be
relied upon to hold the piston forward, and prevent its operation, without resort
being had to the openings 53, 54 and 55. But by reason of the possibility of
accidental displacement of valve 30, from such rearward position, which might
result in shutting off this pressure behind the piston, and opening the exhaust
of such pressure, we prefer to make the cessation of movement of the piston
positive, by providing the ports 53, 54 and 55. It will be seen that the exhaust
behind the head of the valve is open to the exterior through the port 44, and,
further, that accidental displacement of the valve, in the presence of the ports 53,

page_text: .
54 and 55, is prevented by reason of the constant pressure against the forward
end of the valve. In the front end of the cylinder we prefer to introduce a hard
metal bushing or sleeve 56, to receive the tool shank. The forward end of the
piston is also preferably provided with a groove 57, having notches 58 opening in
front thereof, for the purpose of giving a lead to the valve exhaust in advance
of the rearmost position of the piston. Openings 59, are provided in the forward
end of the cylinder back of the bushing 56, to admit the intake and outward paş-
sage of the air drawn in and forced out by the cylinder in its reciprocations. It
will be noticed that we have referred to several of the ports as being in triplicate,
for the purpose of admitting and exhausting a large volume of pressure fluid,
but it is obvious that but one or more of such ports can be used if desired.
By having the body portions 31 and 32 of the valve of different diameters,
the forward being the greater, said valve is thereby unbalanced, with a tendency
at all times to force said valve to the rear, which tends to relieve the valve of
any injurious shocks or jars resulting from contact of the piston stem 42 there-
with: This increased area at the forward end of the valve likewise holds said
valve in its rearmost position, when the piston is in its abnormal forward posi-
tion; as shown in Figure 3. This unequal area of the valve likewise prevents
the valve from throbbing or floating, and makes its movement in either direction
positive.
We may also introduce a jainb nut 60 on the collar or coupling sleeve, to
engage the flange of the handle base, for the purpose of additional security, if
desired.
We are aware that many minor changes in the construction, arrangement and
combination of the several parts of my device can be made and substituted
for those herein shown and described, without in the least, departing from the
nature and principle of the invention.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
1. The combination with a handle, of a throttle valve mounted therein, said
valve comprising a thimble or sleeve, a throttle valve for controlling openings
through said sleeve, an adjustable nut behind said valve, a spring interposed
between said valve and nut, and a sliding cap piece for adjusting said plug;
substantially as described.
2. The combination with a handle of a throttle valve mounted therein, said
valve comprising a thimble fixed in said handle, a sliding throttle valve arranged
in said thimble for closing ports therein, an adjustable nut behind said valve,
a spring interposed between said nut and valve, a sliding cap piece arranged on
said nut for adjusting the same, and means for locking said cap piece against
rotary movement; substantially as described.
3. The combination with a handle, provided with a handle base, of a valve
block abutting against said base, a cylinder against which the other end of said
valve block abuts, and a collar or coupling sleeve for engaging the cylinder and
said handle base for clamping said parts in position, substantially as described.
4. The combination with the handle base and rotary coupling sleeve, which
latter is formed with a series of serrations or notches upon its rear end, of a
spring pressed dog mounted in said handle base for engaging said notches and
preventing said coupling sleeve from unscrewing; substantially as described.
5. The combination with a handle base formed with flanges s, of a valve block
abutting against said handle base, a cylinder 20, provided with a flange v, at
its rear end and abutting against said valve block, a collar or coupling sleeve t,
formed with an inturned flange u, at its front end, which co-operates with the
cylinder flange v, said coupling sleeve having a threaded connection with the
flange s, and a dog e, engaging notches or serrations w, at the rear of said coup-
ling sleeve, said dog being mounted in the flange of the handle base, and being

page_text: provided with a spring for causing its engagement with the collar or coupling
sleeve; substantially as described.
6. The combination with a threaded flange s, of a coupling sleeve t, engaging
therewith, said coupling sleeve being provided with notches or serrations on its
engaging end, a dog, pivotally mounted in the flanges, a torsional spring for
holding said dog in engagement with the coupling sleeve, and a cap piece fixed
on the dog's spindle, by which the dog may be disengaged from the coupling
sleeve; substantially as described.
7. The combination with a cylinder bored to two different diameters, of a
piston of corresponding diameters arranged in said cylinder, and a piston con-
trolling valve which projects into the larger bore of the cylinder, whereby said
valve is positively thrown in one direction by said piston, and a port for inter-
mittently admitting pressure at the other end of said valve; substantially as
described.
8. The combination with a cylinder bored to two different diameters, of a
piston of corresponding diameters arranged therein, said cylinder being provided
with ports for admitting constant pressure in front of the larger head of said
piston, and a valve of two different diameters, which projects into the said larger
bore of the cylinder for intermittently admitting pressure behind the larger head
of said piston, and a port which is controlled by said piston, for intermittently
admitting and exhausting pressure behind the head of said valve; substantially
as described.
9. The combination with a cylinder formed with two different diameters, of
a piston arranged in said cylinder, the body portion of said piston operating in
the smaller diameter, and the larger head of said piston in the larger diameter,
said head.being connected to said body portion by a reduced shank, of a valve
block arranged at the rear end of said cylinder, said valve block containing a
valve of two diameters, which operates in a correspondingly bored opening, a
pressure supply passage having a port which constantly opens in advance of the
larger head of the piston, and having a port which is controlled by said valve,
which port intermittently admits pressure behind the larger head of the piston,
and a port opening behind the head of the valve, which port is controlled by
the piston; substantially as described
10. The combination with a valve block formed with an inlet passage 27,
port 43, exhaust space 39, and port 44, of a hollow valve 30, provided with a
head, and with an axial bore 41, which co-operates with the exhaust passage
when the valve is in a forward position, and a piston for positively moving said
valve to the rear for closing said exhaust passages and opening the inlet port 43;
substantially as described.
11. The combination with a cylinder formed with a bore of two diameters, of
a piston of corresponding diameters arranged in said bore, a valve block abutting
against the rear end of the cylinder, a hollow valve 30, slidingly mounted in said
valve block, the forward end of which valve projects into the cylinder bore, a
head on said valve, and suitable port arrangements whereby pressure is con-
stantly admitted to force the piston to the rear, the pressure behind said piston
being exhausted through the hollow valve, the piston near the rear extremity
of its stroke contacting with the valve to move the same rearwardly and open a
live pressure port to admit a preponderance of pressure behind the piston; sub-
stantially as described.
12. In a pneumatic hammer, the combination with a cylinder bored to two
different diameters, with a shoulder between, a pressure supply duct opening into
the larger chamber near its forward end, a piston having an enlarged head fitting
in the larger bore, and a small body portion fitting in the small bore, said body
portion having a reduced annulus, a valve which projects into the cylinder, and
which is struck by the piston to be moved in one direction, and a port for inter-
mittently admitting pressure behind the other end of said valve for throwing the
same; substantially as described.

page_text: 13. The combination with a cylinder formed with bores of two different dia-
meters, of a piston arrangéd therein, a valve for controlling the admission of
pressure to, and its exhaust from, the chamber behind the piston, said valve
projecting into said chamber in one of its positions where it is struck by the
piston and moved in one direction, a passage leading from behind the valve
and opening into the piston chamber by a port located in advance of the shoulder
between the bores of the cylinder, which port is adapted to be opened and closed
by the piston, an exhaust port 45, in the cylinder in advance of said last named
passage, said cylinder being likewise provided with a port opening 53, for admitt-
ing pressure behind the piston when said piston has moved forward beyond its
normal operating position; substantially as described.
14. The combination with a cylinder bored to two different diameters, of a
piston operating in said cylinder, said piston having constant pressure in front
of its larger diameter for forcing the same rearwardly, and a valve for intermit-
tently admitting and exhausting a preponderance of pressure behind the larger
diameter of the piston, said valve comprising a body portion of two diameters
and a central head, and a port, which is controlled by said piston for admitting
and exhausting pressure to and from behind said valve head; substantially as
described.
1000
PHILIP M. JUSTICE,
Chartered Patent Agent, London, for the Applicants.