Improvements in Pneumatic and other Hammers and Stamps.
Year: 1890

page_text: Date of Application, 14th July, 1890
Complete Specification Left, 13th Apr., 1891-Accepted; 30th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in Pneumatic and other Hammers and Stamps.
I, DANIEL LONGWORTH, 5 and 7, Fenchurch Street, in the City of London,
Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to pneumatic and other hammers and stamps and more
especially to moveable-fulcrum hammers and stamps of the class described in the
Specification of former Letters Patent granted to me on the 8th July 1876,
No. 2794, and it comprises the improvements hereinafter set forth, whereby such
hammers or stamps are rendered more efficient than heretofore.
As the moveable fulcrum described in the Specification of the aforesaid Patent
does not move rapidly enough to vary the force of the blows of the hammer with
the necessary quickness whilst the hammer is in motion, which much of the work
done by hammering requires, I now arrange the moveable fulcrum to be quickly
altered whilst the hammer is at rest, and to rapidly vary the force of the blows
whilst the hammer is in motion. I provide controlling arrangements which may
work in conjunction with but are distinct from the moveable fulcrum.
A rotating crank-shaft works in the framing of the machine and is actuated by a
belt and pulley in the ordinary manner:-This shaft imparts a reciprocating
motion rocking upon a fulcrum-pin placed in the framing of the machine. One end
of this rocking lever has a sleeve sliding upon it connected to the pin of the
crank-shaft, and the other or hammer end of the rocking lever is furnished with
links which are connected to the piston of the actuating air-cylinder of the
hammer or to the actuating air-cylinder itself in the manner to be hereinafter
described.
Two or more holes are made in the framing of the machine, in a line corresponding
with the lowest position of the rocking lever and corresponding holes are made in
the rocking lever, and when it is required to alter the stroke and consequently the
force of the blows of the hammer, the fulcrum-pin is withdrawn from one set of
holes and placed in another set, a temporary pin being provided to hold the rocking
lever in position whilst the change is being effected.
By this arrangement the fulcrum-pin cannot be shifted from its position by the
working of the hammer and the lateral strain upon the hammer guides is con-
siderably reduced, thus enabling the hammer to be run at a high speed.
To rapidly control and vary the force of the blows of the hammer whilst it is in
motion and when required, to prevent the hammer from striking the anvil I arrange
an auxiliary pneumatic cylinder above the hammer or in any other suitable position.
In this cylinder works a piston, which piston is connected by a rod rigidly to the
hammer-head or to parts attached rigidly to the hammer-head.
The controlling cylinder is open at the top, and the controlling action takes place
between the piston and the bottom of the controlling cylinder, and during the
downward stroke of the hammer.
At or near the bottom of the controlling cylinder an inlet valve or valves is or
are fitted.
In the upward stroke of the hammer and controlling piston the inlet
valves open, and admit air between the controlling piston and the bottom of the
controlling cylinder, and on the descent of the piston and hammer the inlet valves
close automatically, the air being confined between the piston and bottom of con-
trolling cylinder and forming a cushion of air sufficient to absorb the force of the
blow and prevent the hammer from striking the anvil or the work thereon.
To regulate the density of this cushion of air and consequently the force of the
blow I furnish the controlling cylinder with a controlling valve preferably of the

page_text: piston type, which valve is placed under the control of the foot or hand of the
workman by suitable mechanism. This controlling valve works in a small cylinder
or chamber attached to, and parallel with the controlling cylinder, which chamber
is open at its top end, and outlet holes or ports are made in the controlling cylinder
at various heights corresponding with the amount of cushioning required. These
holes or ports form a communication between the controlling cylinder and the valve
chamber. When the controlling valve is in its highest position, all these outlet
holes are closed by the valve, and the maximum amount of cushioning and the
minimum force of blow is obtained, by lowering the controlling valve various
degrees of cushioning can be produced and increasing force is given to the blows
when the controlling valve is in its lowest position and all the outlet holes are open
to the atmosphere the maximum blow is given, corresponding with the position of
the fulcrum of the rocking lever at the time being. I can arrange to hold the
inlet valves open when the maximum blow is required."
Instead of or in addition to the controlling piston valve, ordinary plug or screw
down controlling valves may be employed at or near the bottom of the controlling
cylinder.
Instead of fixing the controlling oylinder to the framing of the machine, the
controlling piston may be fixed to the framing of the machine, and the controlling
cylinder attached rigidly to the hammer by two connecting bars
suitable means, the inlet and outlet valves being connected to the fixed controlling
piston.
or other
To still further control the force of the blows whilst the hammer is working,
I can provide for reversing the direction of rotation of the crank-shaft by means of
open and cross-belts and suitable driving pulleys or by other well known appliances.
A brake applied to the fly-wheel of the crank may work in conjunction with this
arrangement and the whole be placed under the control of the foot or hand of the
workman in such a manner that, when rotating in one direction the crank pin in
conjunction with the sliding sleeve of rocking lever causes the hammer to be forced
down quickly and raised up slowly, while by reversing the motion of the crank-
shaft the hammer will be forced down slowly and a lighter blow will be given than
when the shaft revolves in the usual direction.
To prevent the actuating air-cylinder of a pneumatic hammer from being unduly
heated by contact with the hammer-head, I place the air-cylinder at a suitable
distance away from the hammer-head; and I dispense with the usual air-cylinder
guides attached to or formed in the framing of the machine. Where the air-cylinder
is connected rigidly to the hammer, the connection is effected by a neck-piece of
less cross sectional area than the hammer-head so as to diminish the rate of con-
duction of the heat from the hammer-head to the air-cylinder. The air-cylinder
neck-piece and hammer-head form one solid casting or forging. The lower end of
the piston rod of the controlling piston, or the connecting bars of the controlling
cylinder are screwed or cottered to the top of the air-cylinder and the hammer-
head works in guides in the framing of the machine. The air-cylinder is there-
fore guided solely by the hammer-head and piston rod or connecting bars above
described.
The piston of the air-cylinder is connected by a transverse pin with the links of
the rocking lever. This transverse pin is square in section where it passes through
the air-cylinder and the piston and round in section where it passes through the
links, the pin fits the slots in the sides of the air-cylinder but fits the piston only at
its top and bottom sides.
Sometimes the hammer-head is rigidly attached to a piston rod, to which the
air-piston is also rigidly attached. At a suitable distance from the hammer-head
the piston rod passes up through the actuating air-cylinder, and at its upper end is
attached to the controlling piston of the controlling cylinder. The hammer-head
is guided in the framing of the machine, and the piston rod is guided at its upper
end by the controlling cylinder.
The air-cylinder piston rod glands are made as long as possible and the

page_text: air-cylinder is guided solely on the piston rod by its glands and piston, no external
guides of any kind being used.
In order to prevent any lateral strain on the air-cylinder, I connect the links of
the rocking lever to a cross-head which fits and slides upon the piston rod, the said
cross-head being bushed with antifriction metal (or other alloy) where it is in
contact with the piston rod. The cross-head passes through a slot formed in the
gland of the air-cylinder and fits the slot closely at top and bottom only,
the lateral thrust therefore of the links and rocking lever is borne entirely by the
piston rod.
In some cases I connect the cross-head to the air-cylinder in such a manner that,
whilst no lateral strain is thrown upon the air-cylinder, the latter is free to
revolve upon its piston rod, in this case a circular collar formed on the end of the
air-cylinder gland fits closely at the top and bottom only in a slot formed in the
cross-head.
The air-openings leading into the air-cylinder I make in the form of spiral slots
or a series of holes drilled spirally, the vertical length of the slots or series of holes
being of about the same length as the air-cylinder piston. These slots or holes or
the passages leading to them I cover with wire-gauze or other fine material which
will act as a filter to the air to prevent iron scale, mineral or other particles from
entering the air-cylinder.
Where the controlling cylinder is not required I substitute for the controlling
cylinder, a guide-bracket in which the upper end of the piston rod of the hammer
works.
When it is not desirable to guide the hammer-head as in ore stamps and stamps
for beetling fabrics, etc., I guide the lower end of the piston rod, (or the neck-piece
of the air-cylinder) in a suitable bearing in the framing of the machine, suitable
catch trays being provided to prevent oil reaching the hammer-head.
When the hammer is required to give single blows of uniform intensity as in
stamping forgings, raising sheet metal work, etc., I employ a hammer with a rocking
lever moveable fulcrum and air-cylinders as described in this Specification, but instead
of using cams for actuating the hammer as described in my said former Specifi-
cation I connect to the moveable fulcrum rocking lever, an auxiliary lever rocking
on a pin in the framing of the machine. The auxiliary rocking lever has a curved
slot formed in it. The crank-shaft is free to slide in its bearings parallel with its
axis, and on the crank-pin of the crank-shaft I mount a roller which, when a blow
is required, works in the slot of the rocking lever and imparts to it a reciprocating
motion, the curved slot in the rocking lever is so formed that, when the hammer is
at the top of its stroke, a portion of the slot corresponds with the radial path of the
crank-pin, whereby when the crank-pin and roller are passing this portion of the
slot the roller can enter or withdraw from the slot in the rocking lever. To slide
the roller with its crank-shaft to engage with or disengage from the slot I employ
the same disengaging mechanism as described in my former Patent, the inclined
disengaging cams being in this case attached rigidly to the crank-shaft.
In order to keep the hammer in position when it arrives at the top of its stroke,
the rocking lever is furnished with a stop-pin which is moved in and out of the
rocking lever by the sliding movement of the crank-shaft.
In power hammers of large size toothed gearing may be placed between the
driving-shaft and the crank-shaft, so that the driving-shaft rotates faster than the
crank-shaft.

page_text: COMPLETE SPECIFICATION.
Improvements in Pneumatic and other Hammers and Stamps.
I, DANIEL LONGWORTH, of 5 & 7, Fenchurch Street, in the City of London,
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 :—
My invention relates to pneumatic and other hammers or stamps actuated by
rotary shafts, and comprises improvements whereby such hammers or stamps are
rendered more efficient than heretofore.
.1
According to my invention the motion of. the crank-shaft is communicated to
the rod carrying the hammer (which rod is hereinafter referred to as the hammer-
rod) through the medium of a lever pivotted on the frame of the machine, and
connected at one end to the pin of the crank through the medium of a sliding
sleeve and at the other by means of links to a cross-head sliding on the hammer-
rod and carrying what I term an actuating air-cylinder, within which is a piston
secured to the hammer-rod, the said piston with the hammer-rod serving as guides
for the said actuating air-cylinder. The pivot-pin or fulcrum upon which the
lever oscillates or rocks is adapted to be placed in one or other of two or more
sets of holes for adjusting the stroke of the hammer.
For regulating the force of the blows delivered by the hammer, during the
operation of the machine, an auxiliary air-cylinder is fixed to the framing and
contains a piston connected to the hammer-rod. In the upper part of this cylinder
are holes or openings for permitting the free ingress and egress of air and in the
lower part a valve or valves is or are arranged, which valve or valves admit air
below the piston but prevent its escape. At one side of the auxiliary cylinder is
a series of passages controlled by a valve in such a manner that all the said
passages can be closed or one or more opened as required.
To enable my invention to be fully understood will describe the same with
reference to the accompanying drawings, which illustrate my improvements applied
to a pneumatic hammer.
Figure 1 being a sectional front elevation; and,
Figure 2 a section on the line x x Figure 1.
a is the framing of the machine, and b is the crank-shaft supported in bearings
in the framing and carrying belt pulleys c, c¹, the belt running upon which is, as
shewn, designed to be shifted by the workman by means of the belt lever d and
foot-lever d¹, but which may be shifted by hand in the usual manner.
e is the lever pivotted in the framing upon the pin or fulcrum f, and g is the
sleeve sliding upon the said lever at one end and connected to the pin b¹ of the
crank b.
h, h are the links connected to the other end of the lever e and to the cross-
head which fits and slides upon the rod k carrying the hammer k¹, and is the
actuating air-cylinder, a collar on the neck of which fits under flanges on the
said cross-head so that no lateral strain on the cross-head is imparted to
the actuating air-cylinder l. This collar may be screwed upon the neck of the
air-cylinder and furnished with a lock-nut, to enable the said air-cylinder to
be adjusted vertically relative to the position of the cross-head g. m is the piston
attached to the hammer-rod k and working in the actunting air-cylinder l.
In the actuating air-cylinder are holes 12, 12 which serve to admit air above
and below the piston m to form the usual elastic cushion when working, the said
holes being placed in a recess, which, when necessary, is covered with fine wire-
gauze or other suitable material to filter the air.
From the foregoing description it will be understood that, when the lever e is
rocked, a reciprocating up and down movement will be imparted to the hammer-
rod through the medium of the links h, h, the cross-head i, the actuating

page_text: air-cylinder and the piston m. As the links h, h are very long relative to the stroke
of the rocking-lever e very little lateral strain is imparted to the cross-head & and,
as the said cross-head only fits the collar at the top and bottom and does not fit it
sideways, no lateral strain is imparted to the actuating air-cylinder 1, the latter
therefore imparts no lateral pressure to the piston m or hammer-rod k, whereby
packing and packing glands for the hammer-rod k, and external guides for the
body or neck of the air-cylinder can be dispensed with, the actuating air--
If the
cylinder being guided solely by the piston m and hammer-rod k.
links h, are made so long relative to the stroke of the rocking-lever e that,
practically, no lateral strain is imparted to the cross-head i, the latter can be
secured directly to the neck of the actuating air-cylinder l.
n, n and n¹, n¹ are two sets of holes made in the framing a of the machine and
corresponding holes are made in the rocking-lever e, these holes being in a line
corresponding with the lowest position of the rocking lever. To alter the stroke of
the said rocking-lever the fulcrum-pin f is withdrawn from one set of holes and
placed in another set, a pin o being placed in the holes p, p in the lever and frame
to hold the rocking-lever e in position whilst the change 18 being effected. The
dotted lines q, q indicate the range of movement of the rocking-lever when the
pin is in the holes n, n, and n¹, n² respectively..
is the auxiliary piston attached rigidly to the hammer-rod k, and 8 is the
regulating cylinder attached to the framing a of the machine, the hammer-rod, as
shewn, passing through the said cylinder. This regulating cylinder bas, at its
lower end, a long bearings for the hammer-rod k, which bearing ¹ may be
furnished with a stuffing-box and packing gland when necessary. The upper end
of the cylinders is in communication with the atmosphere through openings 83, 8*
under the cover and the lower end is provided with an air-inlet having a
valve t¹. A series of air-inlet holes or openings are formed in the walls of the
cylinder & at a point a little below the piston when the latter is at the top of
the stroke, the said openings 12, with the opening t, serving to admit air under the
piston during its upward stroke. The holes are not furnished with valves and,
when the stroke of the hammer is short, the inlet opening and valve t¹ may be
dispensed with, the inlet holes or openings t² alone being used to admit air under
the piston r.
In a chamber or box u, forming part of or attached to the cylinders and con-
nected. thereto by a series of passages u¹, u¹ at various heights from the bottom of
the cylinder, is placed a slide-valve v. This slide-valve is shewn as connected by
means of rods and levers v², v², v³, v4 to a hand-lever under the control of the
workman, but it may be connected, when required, to the foot-lever d¹ or to a
separate foot-lever. The said slide-valve is also shewn as of the solid piston type,
but any other type of slide-valve may be employed without departing from the
nature of this invention. When the said slide-valve vis in its highest position it
covers and closes the outer ends of all the holes or ports u, ul but, when in its
lowest position, it uncovers the outlet of all the holes which are then free to
communicate with the atmosphere through openings u², u² under the cover of the
box. When, during the upward stroke of the hammer, the piston r rises, air is
drawn into the cylinder below the said piston through the inlet opening t, and
when the piston nears the top of its stroke, through the openings . When the
piston descends and passes the holes and closes the valve t¹, the air is com-
pressed between the said piston and the bottom of the cylinder forming an elastic
resistance to the downward motion of the hammer k³.
When all the holes u¹, u¹ are closed by the valve the maximum amount of
compression and resistance to the downward motion of the hammer is obtained so
that the pallet or head w of the hammer does not strike the block y on the anvil z.
Should, however, all the holes u, u be rapidly uncovered, the hammer would
descend with all its force. A blow of intermediate force is obtained by uncovering
a greater or lesser number of holes, whereby the volume of air compressed in the
cylinder is varied according to the blow required.

page_text: Although I have described my improvements as applied to hammers it is to be
understood that they are equally applicable to stamps.
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 or other hammer or stamp a rocking-lever connected with a
cross-head on the hammer or stamp-rod by means of links, substantially as described.
2. In a pneumatic or other hammer or stamp having a rocking-lever as described,
mounting the said lever upon a pin or fulcrum adapted to be placed in one of a
series of sets of holes in the framing of the hammer, substantially as, and for the
purpose, described.
3. In a pneumatic or other hammer or stamp an actuating air-cylinder, such as 1,
guided solely by its piston and rod k, substantially as described.
4. In a pneumatic or other hammer or stamp a fixed air-cylinder, such as 8,
having inlet openings such as t, t, and outlet ports such as u', u', and controlled
by a slide-valve, all substantially as described with reference to the accompanying
drawings for the purposes specified. `
Dated the 13th day of April 1891.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.