Improvements in Percussive Tools.
Year: 1890

page_text: Date of Application, 21st Oct., 1890
Complete Specification Left, 21st July, 1891-Accepted, 22nd Aug., 1891
PROVISIONAL DI MUITIVATION.
Improvements in Percussive Tools.
I EDWIN FREUND, of 23 Genoa Road, Anerley, in the County of Surrey,
Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
The object of my invention is to effect improvements in the arrangement and
construction of that class of percussive machines, or tools employed for calking,
chipping, shaping and similar operations, and driven by compressed air, steam, or
other suitable elastic fluid, wherein a piston or striker, working in a cylinder,
delivers a blow at each stroke against a tool or toolholder.
In my improved machine, I employ a piston or striker, which is so arranged that
its motion directly opens and closes the inlet and exhaust ports in the cylinder, thus
avoiding the employment of a separate valve for effecting the distribution of the
compressed air, steam, or other fluid. Further, I cause the said piston to strike on
its forward movement against the tool or tool holder, when the front inlet port is
just opening. By this means I secure a regular and firm blow and avoid causing
vibration in the apparatus, because the piston or striker can only follow the tool,
against which it strikes, for a very short distance, while the return stroke is
accelerated by the reaction.
The tool, or tool-holder, is an entirely separate piece, and can be instantly
removed, exchanged, turned round, or reversed, without stopping the movement of
the piston. This is a very convenient arrangement for the attendant, and also
saves time and prevents any chance of overstraining the tube connecting the
machine with the source supplying the driving medium, such overstraining being
liable to occur, if the machine be suddenly stopped.
In operation, the attendant grasps the tool or tool-holder with one hand, while
the other hand grasps a suitable handle provided at the outer end of the cylinder,
or when convenient, the shoulder or chest may be pressed against the said handle.
As every blow of the piston drives the tool a little away from the cylinder, it is
necessary to provide means for its immediate return. In machines of this class,
springs have heretofore been generally employed for this purpose, but in my
improved machine the object is effectively attained by merely pressing the machine
against its work; when in such position a suitable stop on the tool, or tool-holder
bears against a stop on the cylinder, and suitable guides secure the tool being in the
proper position for each blow.
When it is desired to suspend the machine, I provide trunnions on the cylinder,
at or near the centre of gravity of the apparatus and attach a sling links, or other
similar device to the said trunnions, and suspend the machine by a chain or rope
attached to the said sling and passing over a pulley with a counterweight. By this
means the apparatus can readily be turned about on the trunnions, raised or lowered,
and held in any required position, and being suspended from its centre of gravity,
the weight of the machine offers no resistance to its movement by the attendant, the
effect of gravity being practically eliminated.
The said trunnions are preferably hollow and serve as the inlet and outlet for the
air or steam to and from the cylinder, but nozzles separate from the trunnions, may
if preferred, be provided for this
apparatus to machines of the close. I may apply this method of slinging the
described, other than those constructed in
accordance with my invention.
The main advantages of my improved machine over similar existing machines,
are, that only one moving part is employed, that it can be more efficiently handled,

page_text: that the blows are regular and effective, without causing vibration, and that the
cost of manufacture is reduced.
Dated this 21st day of October 1890.
AMBROSE MYALL..
21, Cockspur Street, London, S. W., Agent for the Applicant.
Improvements in Percussive Tools.
I, EDWIN FREUND, of 122 Trinity Road, Upper Tooting, in the County of
Surrey, but late of 23 Genoa Road, Anerley, in the same County, Mechanical
Engineer, 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 object of my invention is to effect improvements in the arrangement and
construction of that class of percussive machines or tools, employed for caulking,
chipping, shaping and similar operations, and driven by compressed air, steam, or
other suitable elastic fluid, wherein a piston or striker, working in a cylinder
delivers a blow at each stroke against a tool, or tool holder.
In my improved machine, I employ a piston, or striker, which is so arranged that
its motion directly opens and closes the inlet and exhaust ports in the cylinder, thus
avoiding the employment of a separate valve for effecting the distribution of the
compressed air, steam, or other fluid. Further I cause the said piston to strike on
its forward movement against the tool, or tool holder, when the front inlet port is
just opening. By this means I secure a regular and firm blow and avoid causing
vibration in the apparatus, because the piston or striker can only follow the tool
against which it strikes for a very short distance, while the return stroke is
accelerated by the reaction.
The tool, or tool holder is an entirely separate piece, and can be instantly
removed, exchanged, turned round, or reversed, without stopping the movement
of the piston. This is a very convenient arrangement for the attendant and
and also saves time and prevents any chance of overstraining the tube con-
necting the machine with the source supplying the driving medium, such over-
straining being liable to occur if the machine be suddenly stopped.
In operation, the attendant grasps the tool, or tool holder with one hand,
while the other hand grasps a suitable handle provided at the outer end of the
cylinder, or when convenient the shoulder or chest may be pressed against the
said handle.
As every blow of the piston drives the tool a little away from the cylinder,
it is necessary to provide means for its immediate return. In machines of this
class springs have heretofore been generally employed for this purpose, but in
my improved machine the object is effectively attained by merely pressing the
machine against its work; when in such position a suitable stop on the tool, or
tool holder bears against a stop on the cylinder, and suitable guides secure the
tool being in the proper position for each blow.
When it is desired to suspend the machine, I provide trunnions on the cylinder,
at or near the centre of gravity of the apparatus, and attach a sling, links, or
other similar device to the said trunnions and suspend the machine by a chain
or rope attached to the said sling and passing over a pulley with a counter-
weight. By this means the apparatus can readily be turned about on the trunnions,
raised or lowered, and held in any required position, and being suspended from its
centre of gravity the weight of the machine offers no resistance to its movement by
the attendant, the effect of gravity being practically eliminated.
The said trunnions are preferably hollow, and serve as the inlet and outlet for the
air or steam, to and from the cylinder, but nozzles, separate from the trunnions, may,

page_text: if preferred, be provided for this purpose. I may apply this method of slinging
the apparatus, to machines of the class described, other than those constructed in
accordance with my invention.
The main advantages of my improved machine over similar existing machines,
are, that only one moving part is employed, that it can be more efficiently handled,
that the blows are regular and effective without causing vibration and that the cost
of manufacture is reduced:
The accompanying two sheets of drawings, represent an apparatus constructed in
accordance with my invention, as also modifications of certain parts.
Fig. 1 is a longitudinal sectional plan of the cylinder, with the piston and tool
removed.
Fig. 2 is a similar sectional view, through a plane at right angles to that of
Fig. 1.
Fig. 3 is a cross section through the lines 2-2 in Figs. 1 and 2.
Fig. 4 is a cross-section through the lines 3-3 in Figs. 1 and 2.
Fig. 5 is a cross-section through the lines 4-4 in Figs. 1 and 2.
Fig. 6 is a cross section through the lines 5-5 in Figs. 1 and 2.
Fig. 7 is an elevation, partly in section, of the piston and rod.
Fig. 8 is a cross-section through the line 6-6 in Fig. 7.
Fig. 9 is an elevation of the piston and rod at right angles to the view shewn in
Fig. 7.
Fig. 10 is a cross section through the line 7-7 in Fig. 9.
Fig. 11 is an elevation of a tool and tool holder, shewing the latter in section.
Fig. 12 is an elevation of a simpler form, of tool not requiring a tool holder.
Fig. 13 is a sectional view of the end of a holder, arranged to carry interchange-
able short tools.
Fig: 14 is an external view of the complete apparatus, to a reduced scale.
Figs. 15, 16 and 17 are diagrammatic sections of a cylinder and piston, shewing the
latter at the centre and the two ends of its stroke, respectively.
Fig. 18 is a longitudinal section of a modified form of piston.
Fig. 19 is a cross-section through the line 8-8 in Fig. 18.
Fig. 20 is a right hand end view of Fig. 18.
Fig. 21 is a longitudinal section of a further modified form of piston.
Fig. 22 is a cross-section through the line 9-9 in Fig. 21.
Fig. 23 is a right hand end view of Fig. 21.
Fig. 24 is a longitudinal section of a cylinder of modified design.
Similar letters of reference denote similar parts throughout the drawings.
Referring to Figs. 1 to 17, A is the cylinder provided at one end with a convenient
handle B, which may be insulated if steam is employed, and at the other with a
stuffing box C and guides D for the tool E. F, Figs. 11 and 14 is a handle screwed
on the tool, and secured, when adjusted to the correct position, by the lock nut H.
The bottom of the recess F forms a stop, which abuts against the end D' of the
guides D.
The tool shewn in Fig. 12 has no separate handle, but is formed with an enlarged
part E', the end of which serves the same purpose as the end of the recess F in
Fig. 11.
In Fig. 13 the end of the rod E is enlarged and provided with a conical
ole, in which short cutting bits E², or other tools can be inserted and changed as
equired.
The striker consists of a piston J, with piston-rod K. The end of this rod and
he end of the tool, or tool holder on which it strikes, are both hardened to reduce
year. LL' are trunnions formed on the cylinder at or about its centre of gravity.
n Fig. 14 a sling M provided with a swivel N is shewn attached to the trunnions,
o that the apparatus can, when required, be suspended from any suitable support.
A convenient arrangement is to attach a chain or rope to the sling, passing over a
ulley and furnished with a counterweight. The apparatus, even if of large size, is
eadily handled and turned in any direction when slung in this manner.
The construction of the ports and passages in the cylinder and piston and their

page_text: action, is as follows. The piston belongs to that class wherein no separate moving
valve, or valves are employed, the piston being so arranged as to open and close the
ports in the cylinder during its traverse and thus to form its own valve.
The trunnion L forms the inlet for the compressed air, steam, or other motor
fluid employed, and the trunnion L' the outlet. PP are the admission ports within 5
the cylinder, communicating with the inlet trunnion L by the passages QQ'. Two
admission ports are employed mainly to balance the pressure upon the piston:
R R are the top exhaust ports, and R2 R3 the bottom exhaust ports. The
ports R R2 communicate with the outlet trunnions L', directly through the
passage S, and the ports R' R³ by means of the annular passages T, T'. Two
longitudinal grooves V V₁ are formed on opposite sides of the piston J, these
grooves come respectively under the inlet ports P P1, and are kept in such position
by a key W in the piston rod K working in grooves WW1 in the cylinder neck,
but any other suitable device may be employed. The bore of the cylinder is
enlarged at X and X', and recesses Y Y and Y Y¹ are formed to communicate 1
respectively therewith. The action is as follows:-The piston-rod end being in
contact with the end of the tool, the motor fluid has access by the ports P P',
grooves V V₁, and recesses Y Y¹ to the end X¹ of the cylinder, the piston is now
driven back, the fluid in the other end of the cylinder escaping through the
ports R R¹ and passages S and T to the outlet trunnion I. The piston: having
reached the end of its stroke, the exhaust ports R R' are closed and the inlet fluid'
has access by the grooves V V' and recesses Y Y, to the end X of the cylinder,
the piston is then driven out again, the exhaust from the under side escaping
through the ports R2 R3 and passages S and T¹, to the outlet trunnion. Cushioning
is obtained at the top end of the cylinder by so arranging the ports and grooves,
that the exhaust is cut off and fresh fluid admitted before the piston reaches the end
of such stroke.
To prevent any possibility of the piston sticking to either end of the cylinder,
so that the inlet fluid cannot gain access to the piston, I may form circular
grooves ZZin each end of the cylinder, and provide grooves a a and b b in the
ends of the piston.
Should the piston stick against the stuffing box end of of the cylinder the fluid
can pass by the groove Z and grooves a a to the undercut part c of the piston,
which will be of sufficient area for the pressure upon it to start the piston; a
similar action will take place at the other end, and for this purpose a recess may be
turned in the end of the piston or in the end of the handle B, which screws into and
closes the cylinder.
The projection E' on the tool or its holder F and the stop D' are an essential
feature of my invention, as they serve to bring the face d of the tool into a certain
position in regard to the ports of the cylinder, simply by the operator pushing the
machine against its work. Neither springs, nor an additional piston, nor any other
special parts are provided for bringing the tool back to this position after the
blow is delivered. If the end e of the striker hits the tool in this position, the
latter will do its work well and the rebound of the former will help it to start on
the return stroke.
If the striker hits too early, sufficient fluid may not have entered the space X¹ to
effect the return stroke. If on the other hand the end of the tool is too far from
the cylinder, the striker will either not reach it, or its energy will have become
more or less exhausted by the prolonged action of the newly admitted fluid, or by
the compression in X'. To get the best effect, the blow should be delivered
immediately after the fluid has been admitted to X'.
When in use the operator places one hand on the handle B, and with the othe
grasps the handle F, or the tool itself when no handle is provided.
If a lighter piston be desired than the solid one previously described, either o
the forms shewn in Figs. 18 to 20, or 21 to 23 may advantageously be employed
In Figs. 18 to 20, holes ff are drilled into the piston and closed at the end b
screw plugs gy', openings h h h h are then made into these holes, so that they s
serv

page_text: the same purpose as the aforesaid grooves V V₁. In Figs. 21 to 23, the piston is
of still lighter form, being hollow at both ends, holes h¹ h¹ h¹³, being provided to
communicate with the hollow parts. For this piston the arrangements of the ports
in the cylinder has to be altered accordingly.
Although the trunnions on the cylinder have been described as forming the inlet
and outlet nozzles, such nozzles may, if preferred, be placed on any other convenient
part of the cylinder, thus in Fig. 24 an inlet nozzle i is shewn communicating with
the interior of a hollow handle B.
Within this handle is a valve j, which, when the end of the stem k is pushed in,
admits the fluid to the passages 1 1, communicating with the admission ports; on
ceasing to press the stem k, the differential pressure on the flange m immediately
closes the valve. The machine can thus be started and kept in operation by merely
pressing the said stem with a finger of the hand which holds the handle B, and
stopped by removing such pressure.
Although the forms of cylinder and piston, which I have described and illustrated
are well calculated to perform the required work, I do not necessarily limit myself
thereto, as I may employ any other design of cylinder and valve piston which will
actuate the tool in the required manner. Thus for instance I
cylinder with a liner, or make the cylinder and one cover in a single piece.
may build
up the
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 percussive tool, driven by compressed air, steam, or other suitable elastic
fluid, the combination of a piston, or striker, which, by means of suitable ports and
passages in the piston or cylinder, or in both, opens and closes the admission and
exhaust and thus dispenses with a supplementary valve; with an independent tool
that by means of suitable projections bears against a stop on the cylinder to which
it is pressed, such tool returning to a definite position after each blow of the striker
by the pressure with which the apparatus is held to the work, and capable of being
exchanged, turned round and handled at will, without stopping the motion of the
piston.
2. The combination with a percussive tool, of the class above described, of
trunnions L L and a sling M for suspending the tool, substantially as set forth.
3. The combination with a percussive tool,.of the class above described, of hollow
trunnions L L' forming the inlet and outlet nozzles for the motor fluid and serving
if required for the attachment of a sling M for suspending the tool, substantially as
set forth.
4. In a percussive tool, of the class above described, the combination with a
tool E, of an adjustable handle F, forming a stop, substantially as and for the
purposes set forth.
5. The combination with a percussive tool, of the class above described, of a
starting valvej opened by the pressure of the hand and closed by the motor fluid,
substantially as described and shewn with reference to Fig. 24.
6. The combination of parts forming the percussive tool, substantially as described
and illustrated in the accompanying drawings.
Dated this 21st day of July 1801
AMBROSE MYALL,
21, Cockspur Street, London, S.W., Agent for the Applicant.