Year: 1888

page_text: We, WILLIAM HORNSBY, of Spittlegate Iron Works, Grantham, in the County of
Lincoln, and PEROY JOHN OGLE of 4 Bishopsgate Street Within in the City
of London, Engineers, do hereby declare the nature of this invention to be as
follows:-
This invention relates to that class of apparatus in which an air cushion is interposed
between the motive power and the stamp head. The stamp is actuated either by an
inverted steam cylinder or a crank on a driven shaft. The air cushion consists of a
cylinder fixed to the piston rod or connecting rod whilst a piston within the air
cylinder is connected to the stamp, or the arrangement may be reversed.
The air cylinder is perforated with holes near the top and bottom so that during
part of the up and down strokes the air can freely escape but forms a cushion during
the remainder of the stroke.
Various ways have been suggested for providing in apparatus of this class for the
wear of the stamp head, for example the piston rod of the air cylinder has been made
adjustable in length but such arrangements have proved sources of weakness in
continuous and rapid movement.
According to this invention we provide for the wear of the stamp head by making
the air cylinder longer than is usual and by making the positions of the air inlets in it
adjustable. For this purpose we provide a number of air inlets at different distances
from the top and bottom of the cylinder preferably arranging them in two spiral lines
upon the surface of the cylinder and we surround the cylinder with a casing having a
longitudinal slot in it and free to turn on the cylinder. We provide a relief valve in
the upper end of the air cylinder for the purpose of regulating the pressure of air
in the cushion.
The holes of one line are arranged vertically over those of the other line so that a
pair of holes one near the top and the other near the bottom of the cylinder are
opposite to the slot the other holes being covered.
By turning the casing this pair of holes is covere and another pair at different
distances from the top and bottom are uncovered.

page_text: In order to turn the stamp head through a small angle, after each blow, to equalize
the wear upon it, we cause the rod, carrying it, to work up and down through the
centre of a ratchet wheel, a feather or feathers being provided at a slight angle
working in a corresponding slot or slots sufficient to turn the ratchet wheel one
tooth.
On the upstroke, the ratchet wheel is held by a pawl, so that the stamp head will be
turned the amount due to the angle of the feather or feathers, while on the downstroke,
the ratchet wheel is free to revolve with the rod, thus, a complete revolution of the
rod is made in as many strokes as there are teeth in the wheel, or, in the alternative,
we cause the rod, carrying the stamp head, to work up and down through the centre
of a worm wheel, a feather or feathers being provided to prevent the worm wheel
from turning relatively to the rod. The worm wheel is actuated from the crank shaft
either by means of an eccentric through a ratchet, or by other means, in such manner
that the piston rod and stamp head are slightly turned after each blow.
It is usual to surround the top of the mortar box which receives the head of the
stamp with screens so that the pulverised ore displaced by the stamp is forced through
them. Usually two or more flat screens have been used which are secured in frames
fixed to the mortar box-this arrangement involves considerable loss of surface and
the construction is heavy.
According to this invention we employ a single cylindrical screen its lower end
being secured to the edge of the mortar box and its upper end secured to a ring
supported on pillars carried by the base of the mortar box. This construction enables
the apparatus to be readily taken to pieces and also provides a much larger screening
surface.

page_text: www
We WILLIAM HORNSBY of Spittlegate Ironworks Grantham in the County of
Lincoln and PERCY JOHN OGLE of 4 Bishopsgate Street Within in the City of
London Engineers 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 firstly to that class of apparatus in which an air cushion is
interposed between the motive power and the stamp head. In such apparatus the
stamp is actuated either by an inverted steam cylinder or a crank on a driven shaft.
The air cushion consists of a cylinder fixed to the piston rod or connecting rod whilst
a piston within the air cylinder is connected to the stamp or the arrangement may be
reversed.
The air cylinder is perforated with holes (near the top and bottom) so that during
part of the up and down strokes the air can freely escape but forms a cushion during
the remainder of the stroke.
Various ways have been suggested for providing in apparatus of this class for the
wear of the stamp head, for example the piston rod of the air cylinder has been made
adjustable in length but such arrangements have proved sources of weakness in
continuous and rapid movement.
According to this invention we provide for the wear of the stamp head and die and
if need be can vary the force of the blow by making the air cylinder longer than is
usual and by making the positions of the air holes in it adjustable. For this purpose
we provide a number of air holes at different distances from the top and bottom of
the cylinder preferably arranging them in two spiral lines upon the surface of the
cylinder and we surround the cylinder with a casing having a longitudinal slot in it
and free to turn on the cylinder.
The holes of one line are arranged vertically over those of the other line so that a
pair of holes one near the top and the other near the bottom of the cylinder are
opposite to the slot the other holes being covered.
By turning the casing this pair. of holes is covered and another pair at different
distances from the top and bottom are uncovered.
The casing may also conveniently be made in two halves each provided with a slot
so that by turning one half about its axis relatively to the other the individual holes
which constitute the pairs can be varied.
We provide a relief valve in the upper end of the air cylinder for the purpose of
regulating the pressure of air in the cushion.
Figure 1 is a side elevation and Figure 2 is a front elevation of the upper part of a
stamp to which this portion of our invention is applied. Figure 3 is a vertical section
and Figure 4 a plan of the air cylinder.

page_text: a is the crank shaft driven by the belt pulley a'. bis the connecting rod its lower
end being pinned by the pin to the air cylinder c which is perforated with two
spiral lines c c of holes (see Figure 3). d (Figure 1) is the piston and d¹ is the
piston rod which forms the stamp stem and head and into the lower end of which
the shoe is inserted. The air cylinder has around it the casing e having the slot e¹
(see Figure 1) in it.
Figure 5 is a vertical section and Figure 6 an elevation of a similar arrangement
but with casing made in two halves e² e each provided with its slot e¹.
The arrangements for turning and locking the casing are not shewn, they may be
of any convenient construction.
In order to turn the stamp head through a small angle after each blow, to equalize
the wear upon it we cause the rod carrying it to work up and down through the
centre of a ratchet wheel, a feather or feathers being provided at a slight angle
working in a corresponding slot or slots sufficient to turn the ratchet wheel one
tooth.
On the upstroke the ratchet wheel is prevented from revolving by a pawl so that the
stamp head will be turned the amount due to the angle of the feather or feathers while
on the downstroke the ratchet wheel is free to revolve thus a complete revolution of
the rod is made in as many strokes as there are teeth in the wheel.
fis the ratchet wheel and f1 (Figure 1) the pawl working into it. 9 is the inclined
feather on the piston rod, or in place of this arrangement we may cause the rod
carrying the stamp head to work up and down through the centre of a worm wheel, a
feather or feathers being provided to prevent the worm wheel from turning relatively
to the rod. The worm wheel is actuated from the crank shaft, either by means of an
eccentric through a ratchet or by other means, in such manner that the piston rod
and stamp head are slightly turned after each blow.
It is usual to surround the mortar box which receives the head of the stamp with
screens so that the pulverized ore displaced by the stamp is forced through them.
Usually two or more flat screens have been used which are secured in frames fixed to
the mortar box-this arrangement involves considerable loss of surface and the
construction is heavy.
According to this invention we employ a continuous screen of cylindrical or other
form made in one or more parts its lower end being secured by a strap to the edge of
the mortar box and its upper end secured to a ring supported on pillars carried by the
base of the mortar box. This construction enables the apparatus to be readily taken
to pieces and also provides a much larger screening surface.
Figure 7 is a sectional plan and Figure 8 a sectional elevation showing the details
of a cylindrical screen constructed in this way and Figures 9 and 10 are similar views
of a long screen with rounded ends, Figure 11. being a transverse section of the same.
In these Figures h is perforated metal or wire gauze its lower end being nipped
between the mortar box j and the strap k its upper end is nipped between the flange
of the ring and the strap m. The ring is supported by the pillars n.
The screen
is made out of one or more sheets of a perforated metal or wire gauze and the vertical
joint or joints are made by nipping its edges between the uprights and the packing
pieces p by driving in the keys q.
When wire gauze is used a grid iron frame is put outside to support it.
In place of being vertical the screen may be inclined at an angle.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim in stamps suitable for pulverizing minerals is :-
1. Varying the dimensions of the air cushions at the ends of the cylinder to
compensate for the wear of the stamp head and die and vary the length of the stroke
substantially as described.
2. The air cylinder perforated with several pairs of holes at different heights and
the casing or casings provided with openings to expose any desired pair and cover the
rest substantially as described.

page_text: 3. The ring carried by pillars or other supports fixed to the mortar box by which
the top of the screen is upheld substantially as described.
4. The method of securing the top and bottom of the screen by means of straps
around the ring and mortar box substantially. as described.
5. The method of securing the joint or joints of the screen by means of a bar or
bars running from the base to the ring on one side of the screen and a wedge
or wedges on the other side substantially as described.
Dated this 22nd day. of November 1888.
CARPMAEL & Co.,
Agents.